Search

Premise of research. The monotypic Lowiaceae remains the least-known family in the plant order Zingiberales, yet it may hold an important key to unraveling the phylogenetic placement of the familie...

Globba is one of the largest genera in the primarily tropical Zingiberaceae. The number of anther appendages is highly diagnostic and has been used along with molecular characters to define subgenera and sections. Four main types of anther morphology are recognized: without appendages and with two, four and six appendages. The six-appendaged anthers are reported here for the first time. Appendages arise from two dorsal ledges that flank the broad connective. Development of two-appendaged and four-appendaged species differs from inception. Previous suggestions that either the proximal or distal appendages of four-appendaged anthers have been lost in two-appendaged species are thus not supported. Early development of six-appendaged anthers is similar to that of four-appendaged species, but two additional, small appendages develop on the ledges between the first-formed appendages. This yields three appendages on each side (six overall). The four appendages of G. geoffrayi differ from all other species in having distal appendages that are much smaller and develop later than the proximal appendages. Development thus suggests that the state in G. geoffrayi evolved from a two-appendaged ancestor. Incorporating this information into a phylogenetic character plot of the number of appendages shows that the possession of two appendages is the most likely plesiomorphic state of the genus, although support for this hypothesis is weak. Our study clarifies the origin and complexity in the development of anther appendages in Globba and highlights their significance in infrageneric relationships in Globba. Two appendages have probably likely arisen at the base of Globba, linked with the presence of a prominent ledge, with variable extensions and reductions of the number of appendages in the various subgenera and sections.

Premise of research. Inflorescence and flower structure in the Musaceae is unique in the Zingiberales. The inflorescence lacks the obvious cincinnus structure that characterizes the order, and the flowers are unisexual. Previous studies were conducted using cultivated varieties and were carried out with sectioned material, which does not permit accurate developmental descriptions. Developmental study of a wild species with modern methods addresses these shortcomings and provides more accurate descriptions.Methodology. Young inflorescences and flowers were collected from botanical gardens in Hawaii and Australia and critical-point dried for observation with a scanning electron microscope.Pivotal results. All shoots and inflorescences have sinistrorse (left-handed) phyllotaxy, and the sequence of flower initiation is usually correlated with this pattern. Initiation begins on the cathodic side of the hand (opposite the direction of phyllotactic rise) and progresses anodically (in the direction of phyllotactic rise). Within this general pattern, the sequence of flower initiation is variable, even within the same inflorescence. Five patterns of initiation are reported, with additional variation within each pattern. Both male and female flowers have similar early developmental patterns but diverge at the time of petal/inner androecial formation. In male flowers the anterior side of the flower develops slightly ahead of the posterior, while in female flowers the posterior side develops slightly ahead of the anterior. While consistently present in the material analyzed here, these differences are not apparent at the time of gynoecial initiation or in the mature flowers.Conclusions. The banana inflorescence is another example of how higher-level phyllotactic patterns can influence the sequence of organ initiation at lower levels. Despite variability in the sequence of flower initiation in a hand, the best interpretation of the hand remains a cincinnus. Variability in inflorescence and floral development is rarely reported and may be more common than currently supposed.

Banana flowers form deep within the stem of the banana plant, long before they appear to us. The flowers occur in groups called hands, and the hands are arranged into larger clusters of flowers. Both the number of flowers in a hand and their pattern of development are different between cultivated (supermarket) and wild species of bananas. In supermarket bananas, each hand has many flowers, and the flowers develop in a regular pattern from right to left. In the wild species called the hairy banana, there is no regular pattern of flower formation. Flowers of the hairy banana are never formed in the regular right-to-left manner as found in the supermarket species. This is surprising and illustrates an important point about science: we do not always get the answers we expect. When they are first formed, banana flowers have no parts. They go through a process to form the flower parts that we see. After we describe how this takes place, we give you a project, so you can see how this happens on your own. You will work as a scientist to discover the pattern of development in banana flowers.

Background Inflorescences are complex structures with many functions. At anthesis they present the flowers in ways that allow for the transfer of pollen and optimization of the plant's reproductive success. During flower and fruit development they provide nutrients to the developing flowers and fruits. At fruit maturity they support the fruits prior to dispersal, and facilitate effective fruit and seed dispersal. From a structural point of view, inflorescences have played important roles in systematic and phylogenetic studies. As functional units they facilitate reproduction, and are largely shaped by natural selection. Scope The papers in this Special Issue bridge the gap between structural and functional approaches to inflorescence evolution. They include a literature review of inflorescence function, an experimental study of inflorescences as essential contributors to the display of flowers, and two papers that present new methods and concepts for understanding inflorescence diversity and for dealing with terminological problems. The transient model of inflorescence development is evaluated in an ontogenetic study, and partially supported. Four papers present morphological and ontogenetic studies of inflorescence development in monophyletic groups, and two of these evaluate the usefulness of Hofmeister's Rule and inhibitory fields to predict inflorescence structure. In the final two papers, Bayesian and Monte-Carlo methods are used to elucidate inflorescence evolution in the Panicoid grasses, and a candidate gene approach is used in an attempt to understand the evolutionary genetics of inflorescence evolution in the genus Cornus (Cornaceae). Taken as a whole, the papers in this issue provide a glimpse of contemporary approaches to the study of the structure, development, and evolution of inflorescences, and suggest fruitful new directions for research.

2015-2016 UNCG University Libraries Open Access Publishing Fund Grant Winner. An experimental test of a biodynamic agriculture method of weed suppression was carried out ingrowth chambers to establish the feasibility of the method as a preliminary to field trials. Fourgenerations of Brassica rapa plants were used in a randomized block design. Treated flatsreceived ashed seeds prepared according to biodynamic indications. Seed weight and countswere measured at the end of each generation, and germination of the control and experimentalseed was investigated at the end of generation four. The biodynamic seed peppers, created andapplied as described here, had no effect on seed production or viability, and did not effectivelyinhibit reproduction of the targeted species over the course of four consecutive treatments.

With their impressive array of floral diversity and a largely-understood phylogenetic relationships, the Zingiberales provide an ideal model clade to test for the roles of genetic and ecological factors driving floral diversification. Many Zingiberales have close associations with particular suites of pollinators, a species-level interaction that is reflected in their overall floral morphology. Here we first discuss the importance of understanding developmental evolution in a phylogenetic context, then use the evolution of floral morphology across the Zingiberales to test the hypothesis that shifts in rates of diversification among these tropical monocots is correlated with shifts in pollination syndrome, suggesting an important role of pollination specificity in driving speciation and floral diversification in the Zingiberales.

A protruding oncus is a projection of the intine in the aperture region. The ubiquitous use of acetolysis in palynological research has led to the presence of a protruding oncus being underreported. Controlled experiments with pollen samples collected from undehisced and dehisced anthers demonstrate that the presence of a protruding oncus is affected by the state of the anther at maturity: dehisced or undehisced and by the preparation technique. In investigating the occurrence of onci, particular attention should be paid both to the dehiscence state of the anthers and the effect of the preparation technique on the intine. Although it has been suggested that protruding onci and pollen buds can be distinguished based on three criteria (size, presence of a large vacuole, separation of the protrusion from the grain), most of these distinctions break down when information is included from more recent studies. Additional study of protruding intinous structures may help clarifing the difference between ...

The effects of heat shock (HS) on the ultrastructure and calcium distribution of Lavandula pinnata secretory trichomes are examined using transmission electron microscopy and potassium antimonate precipitation. After 48-h HS at 40°C, plastids become distorted and lack stroma and osmiophilic deposits, the cristae of the mitochondria become indistinct, the endoplasmic reticulum acquires a chain-like appearance with ribosomes prominently attached to the lamellae, and the plasma and organelle membranes become distorted. Heat shock is associated with a decrease in calcium precipitates in the trichomes, while the number of precipitates increases in the mesophyll cells. Prolonged exposure to elevated calcium levels may be toxic to the mesophyll cells, while the lack of calcium in the glands cell may deprive them of the normal protective advantages of elevated calcium levels. The inequality in calcium distribution may result not only from uptake from the transpiration stream, but also from redistribution of calcium from the trichomes to the mesophyll cells.

The related concepts of paedomorphosis in the secondary xylem, insular woodiness, and secondary woodiness are reviewed and evaluated in order to clearly distinguish the phenomenon involved, and provide a firm foundation for future research in this area. The theory of paedomorphosis refers to the occurrence of certain juvenile xylem characteristics, such as scalariform perforation plates and lateral wall pitting, in the secondary xylem of shrubby, suffrutescent, pachycaulous, and lianoid growth forms. Paedomorphic characteristics are often found in insular woody species, a fact that has caused paedomorphosis to be associated with secondary woodiness. The anatomy of the secondary xylem in Xanthorhiza simplicissima (Ranunculaceae), Coreopsis gigantea (Asteraceae), and Mahonia bealei (Berberidaceae) is described in order to provide specific data for discussion. These species serve as test cases for the presence of paedomorphosis, and the evolution of secondary woodiness. The secondary xylem of all three species was found to have a degree of paedomorphosis, with Coreopsis having the greatest number of paedomorphic characteristics, Xanthorhiza having an intermediate number, and Mahonia possessing only a single characteristic. Plotting the occurrence of the character states woody and nonwoody on phylogenetic trees containing these taxa shows that Coreopsis is secondarily woody, while the ancestry of the other two species cannot be unambiguously established. These results must, however, be considered preliminary as the occurrence of secondary growth in many “herbaceous” plants often goes unreported. Although paedomorphosis is often associated with secondary woodiness, there are examples of paedomorphic wood in primitively woody taxa. One conclusion is that the degree of paedomorphosis may be a better indicator of the mechanical requirements of the shoot then of its evolutionary history.

Calcium distribution during peltate and capitate glandular trichome development in Lavandula pinnata L. was examined with the potassium antimonate precipitation method. In order to establish a role for calcium in the secretory process and elucidate calcium function in the glands, the effects of calcium removal were investigated by treatment with nifedipine (Nif, a calcium channel blocker) and Ethylene glycol-bis (2-aminoethyl ether)-N, N, N′, N′-tetraacetic acid (EGTA, a calcium chelator). Untreated, mature glands accumulate many calcium precipitates in the subcuticular space and adjacent cell wall during secretion. In Nif or EGTA treated plants these precipitates disappear, and the amount of secretory product is drastically reduced. Calcium removal also results in a reduction in gland density, cells with decreased cytoplasmic density, formation of a lax cell wall, abnormal formation of the subcuticular space, thinning of the cuticle, and the presence of multivesicular bodies near the plasma memb...

The reproductive morphology of Sargentodoxa cuneata (Oliv) Rehd. et Wils. is investigated through field, herbarium, and laboratory observations. Sargentodoxa may be either dioecious or monoecious. The functionally unisexual flowers are morphologically bisexual, at least developmentally. The anther is tetrasporangiate, and its wall, of which the development follows the basic type, is composed of an epidermis, endothecium, two middle layers, and a tapetum. The tapetum is of the glandular type. Microspore cytokinesis is simultaneous, and the microspore tetrads are tetrahedral. Pollen grains are two-celled when shed. The mature ovule is crassinucellate and bitegmic, and the micropyle is formed only by the inner integument. Megasporocytes undergo meiosis resulting in the formation of four megaspores in a linear tetrad. The functional megaspore develops into an eight-nucleate embryo sac after three rounds of mitosis. The mature embryo sac consists of an egg apparatus (an egg and two synergids), a central cell, and three antipodal cells. The pattern of the embryo sac development follows a monosporic Polygonum type. Comparisons with allied groups show that Sargentodoxa shares more synapomorphies with the Lardizabalaceae than other Ranunculales. Characteristics of its reproductive morphology are consistent with the placement of Sargentodoxa as the sister group of the remaining Lardizabalaceae. It does not possess a sufficient number of apomorphic characters to justify its separation into a separate family or subfamily. It is best retained as a member of the Lardizabalaceae.

Phylogenetic studies have improved Naucleeae classification, but the relationships among the subtribes remain largely unresolved. This can be explained by the inadequate number of synapomorphies shared among these lineages. Of the 49 morphological characters used in phylogenetic analyses, none were from pollen. It has been proposed that H-shaped endoapertures form a synapomorphy of the Naucleeae. Further study of Naucleeae pollen is needed to test this hypothesis as the endoapertures of many Naucleeae genera are unknown. Pollen morphology of 24 species was examined using scanning electron and light microscopy. Naucleeae pollen is very small to small, with a spheroidal to subprolate shape in equatorial view. Three compound apertures are present, each comprised of a long ectocolpus, a lolongate to (sub)circular mesoporus, and an often H-shaped endoaperture. The sexine ornamentation is microreticulate to striate, rugulate, or perforate. Pollen wall ultrastructure of five species was studied with transmission electron microscopy. The exine is composed of a perforated tectum, short columellae, and a thick nexine. The nexine is often differentiated into a foot layer and an endexine, and thickened into costae towards the aperture. The intine often protrudes from the aperture forming a protruding oncus. Our observations support the phylogenetic delimitation of the Naucleeae sensu Razafimandimbison and Bremer, but pollen morphology is of little value in distinguishing the subtribes and genera of the Naucleeae. Ancestral state reconstruction using MacClade is unambiguous in showing that the possession of an H-shaped endoaperture and protruding onci (a new character for the tribe) form morphological synapomorphies of the clade Hymenodictyon+ Naucleeae.

Potassium antimonite was used to locate calcium in the anthers of Torenia fournieri (Linderniaceae). Abundant calcium precipitates accumulate in the microsporocyte cytoplasm. After meiosis, calcium precipitates are abundant on the microspore wall, as well as the callosic wall of each tetraspore. A large number of calcium precipitates also occur on the outer membranes of the tapetal cells, and in the intercellular spaces of the endothecium and middle layer. The quantity of calcium precipitates in the cytoplasm and nucleus increases at the early microspore stage, then gradually deceases until pollen maturation. Calcium precipitates on the pollen wall gradually increase from the early microspore stage until pollen maturation. Numerous calcium precipitates are observed around the Ubisch bodies. The relation between the distribution of calcium and mitosis, nuclear displacement, the formation of the pollen cell wall, as well as the possible functions of anther walls and Ubisch bodies in the transportation of calcium to the mature pollen are discussed.

The pollen morphology and ultrastructure of 20 species, representing eight genera of the Magnoliaceae are described based on observations with light, scanning and transmission electron microscopy. The family represents a homogeneous group from a pollen morphological point of view. The pollen grains are boat-shaped with a single elongate aperture on the distal face. The tectum is usually microperforate, rarely slightly or coarsely rugulose. Columellae are often irregular, but well-developed columellae do occur in some taxa. The endexine is distinct in 14 species, but difficult to discern in the genera Parakmeria, Kmeria and Tsoongiodendron. Within the aperture zone the exine elements are reduced to a thin foot layer. The intine has three layers with many vesicular-fibrillar components and tubular extensions in intine 1. The symmetry of the pollen grains, shape, type of aperture and ultrastructure of the intine show a remarkable uniformity in the family. Nevertheless there is variety in pollen size, ornamentation and the ultrastructure of the exine. The pollen of Magnoliaceae is an example of an early trend of specialization, and supports the view that Magnoliaceae are not one of the earliest lines in the phylogeny of flowering plants.

The morphology, histochemistry, and ultrastructural aspects of the secretion of Lavandula pinnata L. (Lamiaceae) glandular trichomes were studied in order to prepare for work on calcium distribution in normal and heat stressed plants. The secretory process was observed in both light and dark-grown plants. The secretion of the capitate glandular trichomes consists of both lipophilic and polysaccharidic substances (mainly the latter), while peltate glandular trichomes only secrete lipophilic substances. Our ultrastructural results are consistent with the finding that plastids are the main organelle that synthesizes the lipophilic substances, especially terpenes, while dictyosomes synthesize polysaccharides. The essential oil is most likely transported directly by the RER, while the polysaccharides reach the plasma membrane via Golgi-derived vesicles. Exocytosis is the main way that secretory products move from the cell to the subcuticular space. There are no differences in gland development or secretion between the light and dark-grown plants.

Microsporogenesis and male gametogenesis of Jatropha curcas L. (Euphorbiaceae) was studied in order to provide additional data on this poorly studied family. Male flowers of J. curcas have ten stamens, which each bear four microsporangia. The development of the anther wall is of the dicotyledonous type, and is composed of an epidermis, endothecium, middle layer(s) and glandular tapetum. The cytokinesis following meiosis is simultaneous, producing tetrahedral tetrads. Mature pollen grains are two-celled at anthesis, with a spindle shaped generative cell. A few abnormal microspores were observed following the early stages of microgametophyte development.

A new method for working with morphological characters is described and explored in experiments using human participants. The method uses direct comparison and sorting of images to produce hierarchical character-cladograms. A character-cladogram is a graphical representation of a single character that serves as a hypothesis of phylogeny based on that character. Each dichotomy in the character-cladogram represents a character state. Character states are unnamed, thus avoiding problems that arise through the application of verbal labels. Experiments with human participants are used to explore the conditions under which direct comparison produces reliable (consistent from investigator to investigator) and valid (in agreement with an independent estimate of phylogeny) characters. Participants were drawn from students taking a course in plant diversity at UNC Greensboro, and professional plant morphologists attending the Botany 2004 meetings. The students were randomly assigned to trained and untrained groups. Training was carried out using a method that has been shown to change a participant‘s mode of visual processing from analytic (the mode used by visual novices) to holistic (an additional mode only employed by visual experts). Morphologists (no specialists of the taxonomic group) were included in the study to investigate the effects of disciplinary expertise on the ability to describe character-cladograms. They received no additional training beyond that available to them as disciplinary experts. The results suggest an improvement in both reliability and validity after the training regime. We found no support for the idea that the morphologists differed from untrained students in their ability to produce reliable or valid character-cladograms. Disciplinary expertise may not translate into the ability to make reliable and valid assessments of similarity in an unfamiliar visual domain. Based on these results, we suggest a method for creating morphological characters and character states.

Hofmeister's rule is an empirical heuristic derived from the observation that new leaf primordia are formed in the largest space between the existing flanks of the older primordia. These observations have been repeatedly validated in studies of leaf arrangement, but there has been little attempt to extend them to inflorescence and floral organs. This investigation demonstrates the validity of Hofmeister’s observations to cincinnus and early flower development in Phenakospermum guyannense (Strelitziaceae) and Heliconia latispatha (Heliconiaceae) and relates these results to Paul Green’s work on the biophysics of organ formation. The cincinni of Phenakospermum and Heliconia arise in the axils of primary bracts and produce a prophyll, continuation apex, and flower in regular succession. The shapes and orientations of the apical regions of the cincinni are correlated with the placement of these organs, which in turn effect the positions of the sepals and their sequence of formation. The result is two rows of ...

The software program Visual Learning—Plant Identification offers a solution to problems in category learning, such as plant identification. It uses well-established learning principles, including development of perceptual expertise in an active-learning format, spacing of practice, interleaving of examples, and testing effects to train conceptual learning., Learning to identify organisms is extraordinarily difficult, yet trained field biologists can quickly and easily identify organisms at a glance. They do this without recourse to the use of traditional characters or identification devices. Achieving this type of recognition accuracy is a goal of many courses in plant systematics. Teaching plant identification is difficult because of variability in the plants’ appearance, the difficulty of bringing them into the classroom, and the difficulty of taking students into the field. To solve these problems, we developed and tested a cognitive psychology–based computer program to teach plant identification. The program incorporates presentation of plant images in a homework-based, active-learning format that was developed to stimulate expert-level visual recognition. A controlled experimental test using a within-subject design was performed against traditional study methods in the context of a college course in plant systematics. Use of the program resulted in an 8–25% statistically significant improvement in final exam scores, depending on the type of identification question used (living plants, photographs, written descriptions). The software demonstrates how the use of routines to train perceptual expertise, interleaved examples, spaced repetition, and retrieval practice can be used to train identification of complex and highly variable objects.

Students studying either animal or veterinary science at Charles Sturt University are required to be competent in recognising a range of plants that are potentially poisonous to domestic grazing animals. In 2013 these students used a newly developed application ‘Visual Learning – Agricultural Plants of the Riverina’ (VL-APR) for their poisonous plant recognition training. VL-APR has two main advantages over poisonous plant books or other computer-based applications. Firstly, an average of nine images per species is available, so a range of growth stages and variation in structure is shown. Secondly, multiple interactive quizzes and tests are available so students are actively engaged in the learning process. At the start of session the animal and veterinary science students obtained an average class mark (for recognition of 40 species) of 11.9%, with a wide range of individual student marks (0.0 to 40.0%). A class of first year agricultural science students was also tested and scored a similar ave...

Throughout her work Agnes Arber argues for an inclusive, synthetic concept of the vascular plant as `consisting of a unification of every phase of its existence'. Her view of the leaf as a partial-shoot reflects this unification by relating the part (leaf) to the whole (shoot). According to Arber's view of the plant, the part can be fully understood only in the context of the whole. Morphological character description as it is currently practiced in systematics isin sharp contrast with this holistic view of plant structure. Systematic characters are removed from their context when they are described. This problem is greatest when characters are expressed verbally. Verbal descriptions convey little of the content of the character. A shift from verbal to visual charactersallows systematists to capture more information, including some of the context in which the character occurs. By using a photograph, the fringe on a labellum of Alpinia spp. (Zingiberaceae) can be viewed in the context of the labellum in a way that the word `fringe' cannot convey. The use of pictorial charactersalso allows reliable data storage and retrieval from databases, much as DNA sequences are currently being stored and retrieved. Key words: Agnes Arber, character concept, character state, cladistics, database, holism, partial-shoot theory, phylogeny, phylogenetic systematics, plant morphology, process morphology, typology.

Primary inflorescence bracts are initiated in a spiral phyllotactic pattern on the flanks of the inflorescence apex. A cincinnus primordium forms in the axil of each primary bract. A prophyll is initiated in the transverse plane and later extends around the periphery of the cincinnus to produce a sheathing, but not tubular, bract. The apex of the cincinnus forms a flower. Flower development begins with the enlargement and flattening of the floral apex. Sepal initiation is sequential but differs in the first two flowers of a cincinnus. The different sequences are likely the result of developmental constraints that operate at the time of sepal initiation. After initiation, the margins of the sepals become confluent and intercalary growth produces the synsepalous calyx. The periphery of the flower, interior to the sepals, now rises to form a ring primordium composed of three common petallandroecial primordia. The common primordia enlarge, flatten, and separate to produce a petal to the exterior and an androecial member to the interior. The outer androecium forms in the regions of the ring primordium left vacant by the formation of the other floral parts. The anterior outer androecial member soon ceases growth and contributes only initially to the formation of the labellum. The gynoecium shows heterochrony in its time of initiation, which occurs much earlier than in other species of Zingiberaceae. Gynoecial initiation takes place on the margins of the central flora cup, at the time of the separation of the common primordia. Three gynoecial primordia from in antipetalous positions. Septa development differs in the basal and apical portions of the ovary. At the base, the primordia grow inward and fuse to form the central axis of the ovary. At the apex, there is little radial growth of the primordia. They cease growth soon after initiation and produce a unilocular cavity. Ovules form at the junction of these two regions and project up into the cavity. Epigynous nectaries form after all other floral organs.

Flower organogenesis in Hedychium gardnerianum and Hedychium coronarium begins with the sequential formation of the sepals on a rounded–triangular apex. Growth in three regions of the apex, inside the sepals, produces three common petal – inner androecial primordia. Intercalary growth below and between these primordia produces a floral cup, the site of gynoecial formation. The common primordia separate to form petals and inner androecial members. After separation, the anterior inner androecial members fuse to form the labellum. The posterior member forms the polleniferous stamen. Up to this point in development, the flowers of H. coronarium are slightly ahead of those of H. gardnerianum. However, in H. gardnerianum, initiation of the two thecae of the stamen occurs immediately following the separation of the common primordia, while thecae formation in H. coronarium is slightly delayed. These results show that the relative timing of developmental events can vary even over a short developmental period. Formation of the outer androecium takes place at the apices of a triangle formed by the inner androecial members. The anterior outer androecial member aborts soon after formation, whereas the posterior outer androecial members form the two petaloid staminodes that are found on the lateral sides of the labellum in the mature flower. Key words: flower development, flower structure, inflorescence, stamen, Zingiberaceae, Hedychium.

The inflorescence of Orchidantha maxillarioides is similar to a richly branched, polytelic truncate synflorescence. It consists of two to three paracladia borne in the axils of the uppermost phyllomes of the shoot. Each paracladium consists of six bracts. The lowermost bract is the sterile prophyll. The second and third bracts subtend paracladia of the next higher order. The fourth bract subtends a single flower. The fifth and sixth bracts are initiated but do not complete development. Initiation of the paracladia in the axils of bracts 2 and 3 is acropetal, but their differentiation is basipetal. The flowers are trimerous, with a perianth differentiated into sepals and petals. One petal is enlarged to form a labellum. There are five stamens, one inserted opposite each perianth member except the labellum. The ovary is inferior and is closed by a prolongation many times the length of the locular region of the ovary. Floral organ initiation begins with the posterior sepals. The anterior sepal is formed slightly later, at the same time as the initiation of the corolla. The anterior petals arise from primordia that produce only these organs, while the posterior petal (the labellum) arises from a common petal/stamen primordium. The petal/stamen primordium separates into the labellum and the two posterior outer stamens. The anterior outer stamen is initiated slightly later, in the region between the anterior petals. Throughout these stages a floral cup forms below the floral parts. The two inner stamens are initiated simultaneously on the inner surface of this cup, near the insertion of the anterior petals. Three gynoecial primordia are initiated at the top of the floral cup in the region that will form the prolongation. The primordia extend proximally to form the ovary proper and distally to form the style and stigma. The prolongation is formed through intercalary growth. Based on structural and functional similarities in the prolongation and inflorescence, we support placement of the Lowiaceae as the sister group of the Strelitziaceae.

We present new comparative data on early floral development of Heliconia latispatha, an ecologically and horticulturally important tropical plant within the order Zingiberales. Modification of the six members of two androecial whorls is characteristic of Zingiberales, with a reduction in number of fertile stamen from five or six in the banana families (Musaceae, Strelitziaceae, Lowiaceae, and Heliconiaceae) to one in Costaceae and Zingiberaceae and one-half in Marantaceae and Cannaceae. The remaining five infertile stamens in these later four families (the ginger families) are petaloid, and in Costaceae and Zingiberaceae fuse together to form a novel structure, the labellum. Within this developmental sequence, Heliconiaceae share with the ginger families the possession of an antisepalous staminode, a synapomorphy that has been used to place Heliconiaceae as sister to the ginger family clade. Here, we use epi-illumination light microscopy and reconstruction of serial sections to investigate the ontogeny of the Heliconia flower with emphasis on the ontogeny of the staminode. We compare floral development in Heliconia with that previously described for other species of Zingiberales. A comparison of floral structure and development across Zingiberales is presented to better understand the evolution of the flower in this charismatic group of tropical plants.

We present the first visual, as opposed to illustrated, keys to a group of taxa. The creation of four visual keys to the Fagaceae of the southeastern United States are described, one for each of the following characteristics: leaves, buds, fruits, bark., Background and aims Advances in digital imaging have made possible the creation of completely visual keys. By a visual key we mean a key based primarily on images, and that contains a minimal amount of text. Characters in visual keys are visually, not verbally defined. In this paper we create the first primarily visual key to a group of taxa, in this case the Fagaceae of the southeastern USA. We also modify our recently published set of best practices for image use in illustrated keys to make them applicable to visual keys. Methodology Photographs of the Fagaceae were obtained from internet and herbarium databases or were taken specifically for this project. The images were printed and then sorted into hierarchical groups. These hierarchical groups of images were used to create the ‘couplets’ in the key. A reciprocal process of key creation and testing was used to produce the final keys. Principal results Four keys were created, one for each of the parts—leaves, buds, fruits and bark. Species description pages consisting of multiple images were also created for each of the species in the key. Creation and testing of the key resulted in a modified list of best practices for image use visual keys. Conclusions The inclusion of images into paper and electronic keys has greatly increased their ease of use. However, virtually all of these keys are still based upon verbally defined, atomistic characters. The creation of primarily visual keys allows us to overcome the well-known limitations of linguistic-based characters and create keys that are much easier to use, especially for botanical novices.

Ovary anatomy and organography was investigated in five species of Heliconia (Heliconiaceae) and three species of Musa (Musaceae). The ovaries of both genera may be longitudinally divided into three regions: sublocular, locular, and prolongation. The prolongation is the elongated closure of the top of the locules. The proportions of these regions differ between genera and to a lesser extent among species within a genus. In general, Heliconia has a larger sublocular region while the prolongation is larger in Musa. These differences are correlated with the occurrence of gynopleural nectaries in the sublocular region of the Heliconiaceae and in the prolongation of the Musaceae. Anatomical and organographic details are related to our knowledge of the development of the ovary and fruit. Many anatomical differences between the genera are correlated with the functions of these regions in the fruit. The structure and homology of the placental trichomes of the Musaceae are discussed, and I conclude that they are not homologous to the arils of the other Zingiberales. Key words: plant morphology, plant anatomy, nectaries, monocotyledons.

The morphology and histology of the ovary is investigated in four species representing the four genera of the family Costaceae. Only one species of Costus has been investigated prior to this study. The present study identifies new characters and confirms or corrects those previously reported for all four genera. Aspects of ovary structure studied include the general topography and histology of the ovary, paths of the stylar canals, the prolongation of the ovary above the locules, the presence of a vascular plexus at the top of the ovary, and the position and structure of the floral nectary. These characters contribute to a broader data base for phylogenetic analysis of the Zingiberales.

Homeosis has played an important role in the evolution of the flowers of the Zingiberales, especially those of the Ginger Group. In the Zingiberaceae, two members of the outer androecial whorl are replaced by a lip, and two members of the inner androecial whorl are replaced by petaloid staminodes. Most of the androecium of the Costaceae has also been replaced by petaloid structures, and the single fertile stamen is often attached to an enlarged petaloid "filament." The Cannaceae and Marantaceae have one-half of one fertile anther and three to four variously modified staminodes. In contrast, homeosis has played a minor role in floral evolution of the Banana Group. Only in the Heliconiaceae has a stamen been replaced by a staminode. In none of the families of the Zingiberales do the staminodes assume the total "form or character" of any perianth members. Because of this, it is reasonable to extend the definition of homeosis to include replacement by an organ like, but not identical to, some other part of the plant.

Lamina size, thickness, venation, and anatomy are studied in 15 species of Heliconia (Heliconiaceae), 3 species of Musa, and 1 of Ensete (Musaceae). The most typical laminas of these genera are large and oblong and have an acute or irregular apex and an asymmetrical cordate base. The laminar veins are parallel and are oriented essentially perpendicular to the costa and the margin. However, there is considerable variation in lamina architecture in the Heliconiaceae. Thickness ranges considerably across the lamina, with considerable variation between species. The only pattern common to all species is that the blades are thinner at the margin than at the costa. The veins of the lamina occur in a number of size classes that are arranged into a repeating unit called a set. Set patterns are described for the species and families. Although the Heliconiaceae and Musaceae do not differ in general set pattern, variation in the Heliconiaceae tends toward simpler sets, whereas the Musaceae tends towards more complex sets. Lamina anatomy is similar to that reported in the literature for these families, with several notable exceptions. The Heliconiaceae and Musaceae may be distinguished by characteristics of their lamina anatomy and by the fact that Musaceae blades have an irregular apex. The value of these characters for taxonomic and cladistic analyses is discussed. Key words: leaves, plant anatomy, vasculature, Zingiberales, Musaceae, Heliconiaceae.

Keys are character based tools for plant identification. They are based on the decomposition of the plant into very small, atomistic parts. These parts are described with the technical and often arcane terminology of plant taxonomy. Even the best electronic keys (Delta, Lucid) make use of this terminology. Keys are not based on pattern recognition, the forte of visual experts. Instead they demand that the user look at the plant as if it consisted of a series of isolated parts that are classified by name. Keys would be more effective if they were visually based. They would be easier to use for visual experts because accurate perception is their providence. They would also be easier to use for novices because they would not depend on knowledge of arcane terminology. This paper proposed an innovative image-based key system for species recognition.

This paper discusses problems with labelling plant structures in the context of attempts to create a unified Plant Structure Ontology. Special attention is given to structures with mixed, or doubtful identities that are difficult or even impossible to label with a single term. In various vascular plants (and some groups of animals) the structural categories for the description of forms are less distinct than is often supposed. Thus, there are morphological misfits that do not fit exactly into one or the other category and to which it is difficult, or even impossible, to apply a categorical name. After presenting three case studies of intermediate organs and organs whose identity is in doubt, we review five approaches to categorizing plant organs, and evaluate the potential of each to serve as a general reference system for gene annotations. The five approaches are (1) standardized vocabularies, (2) labels based on developmental genetics, (3) continuum morphology, (4) process morphology, (5) character cladograms. While all of these approaches have important domains of applicability, we conclude that process morphology is the one most suited to gene annotation.

The spiromonostichous phyllotaxy of Costus, and other Costaceae, is characterized by low divergence angles, often as low as (30°—) 50°. This constrasts with the main series Fibonacci (divergence angles ap-proximating 137.5°) or distichous phyllotaxy found in all other Zingiberales. A morphological and devel-opmental study of three species of Costus revealed a number of facts about this unusual phyllotactic pattern. In C. scaber and C. woodsonii the divergence angles gradually change along a shoot, from 140°-100° in the region of the cataphylls to 60°-45° in the inflorescence. In C. cuspidatus, the divergence angles change from 40°-100° in the cataphyll region to ca. 137° in the inflorescence. In all three species, the cataphylls and foliage leaves have tubular sheaths, while the inflorescence bracts are nonsheathing. Thus, spiromo-nostichy is only loosely correlated with closed leaf sheaths.

Evolutionary developmental biology often combines methods for examining morphology (e.g., scanning electron microscopy, SEM) with analyses of gene expression (e.g., RNA in situ hybridization). Due to differences in tissue preparation for SEM and gene expression analyses, the same specimen cannot be used for both sets of techniques. To aid in the understanding of morphological variation, it would be particularly useful to have a high-magnification image of the very same sample in which gene expression is subsequently analyzed. To address this need, we developed a method that couples extended depth of field (EDF) epi-illumination microscopy to in situ hybridization in a sequential format, enabling both surface microscopy and gene expression analyses to be carried out on the same specimen. We first created a digital image of inflorescence apices using epi-illumination microscopy and commercially available EDF software. We then performed RNA in situ hybridizations on photographed apices to assess the expression of two developmental genes: Knotted1 (Kn1) in Zea mays (Poaceae) and a PISTILLATA (PI) homolog in Musa basjoo (Musaceae). We demonstrate that expression signal is neither altered nor reduced in the imaged apices as compared with the unphotographed controls. The demonstrated method reduces the amount of sample material necessary for developmental research, and enables individual floral development to be placed in the context of the entire inflorescence. While the technique presented here is particularly relevant to floral developmental biology, it is applicable to any research where observation and description of external features can be fruitfully linked with analyses of gene expression.

Phytolacca dioica has a primary vascular system which includes medullary bundles. The primary structure of these bundles is composite, consisting of two to four collateral vascular strands with their phloem poles oriented toward a common center. A cambium is formed between the xylem and phloem of the strands and extends to enclose the phloem of the whole bundle. After a period of cambial activity the medullary bundles become amphivasal. As is typical of species with helical phyllotaxy, the primary vascular system is organized into sympodia. The medullary bundles form the distal portions of the median leaf traces and continue in a medullary position for the number of nodes equal to the denominator of the phyllotactic fraction characterizing a given stem. As a medullary bundle passes out into a leaf, two or three vascular strands pass inward from the vascular cylinder to form a new medullary bundle. The number of medullary bundles in a stem is, thus, maintained. Variations of this pattern occur in the basal regions of juvenile shoots and in the basal and apical regions of adult flowering shoots. The relationship between leaf arrangement and the passing of vascular strand into the pith is discussed and a new classification of vascular systems with medullary bundles is proposed.

Adventitious shoots and roots were regenerated from leaf segments of 3 Solanum species: S. candidum Lindl., S. quitoense Lam. and S. sessiliflorum Dunal. Leaf explants differentiated shoots on modified MS medium supplemented with 23-163 µm kinetin and 0-5.7 µm indoleacetic acid (IAA). Excised shoots were induced to form roots by transfer to media with benzyladenine (BA) and naphthaleneacetic acid (NAA) at 0.09 and 0.11/2 µM respectively for S. qultoense and 0.01 µm NAA for S. candidum and S. sessiliflorum. Adventitious roots were produced directly from leaf explants with 0-140 µm kinetin and 0-5.7µm IAA in combination. Rooted plants were successfully established in the greenhouse.

Nonstructural, foliar nectaries have been found in two genera of the Marantaceae (Zingiberales). Two nectaries are located on each leaf, at the junction of the leaf sheath and petiole. Externally, they may be readily distinguished from the surrounding tissue by their lighter color and absence of hairs. Internally, they show no specifically differentiated nectariferous tissue. In most species, the location of the nectaries is correlated with the distribution of fiber bundles. In nonncctariferous regions these bundles lie directly beneath the epidermis, while in the region of the nectary they occur several cell layers beneath the epidermis. Nectar secretion takes place through stomates. The cells surrounding the substomatal cavity may play an important role in the process of secretion. The distribution of structural nectaries in the family is also discussed.

The inflorescence of Costus scaber terminates an erect axis of a sympodial rhizome system. Primary bracts are borne on the inflorescence in spiral monostichous phyllotaxy. One-flowered cincinni occur in the axils of these bracts. Each cincinnus consists of an axis bearing a terminal flower and a secondary bract on the anodic side of the flower. A tertiary bud forms in the axil of this bract but does not complete development. The inflorescence terminates by cessation of growth of the apex and precocious development of the primary bracts. Floral organs are formed sequentially beginning with the calyx, and continuing with the corolla and inner androecial whorl, outer androecial whorl, and gynoecium. All flower parts, except for the calyx, originate from a ring primordium. Regions of this primordium separate to form the corolla and inner androecial members. It was not possible to determine the sequence of androecial member formation. The labellum is composed of five androecial members, three from the outer whorl and two from the inner. The third member of the inner whorl forms the stamen and its petaloid appendage. The gynoecium forms from three conduplicate primordia. The margins of two of these primordia are the product of phyietic fusion.

Phytolacca dioica (L.) is characterized by anomalous secondary thickening by means of supernumerary cambia. After a period of primary growth and the formation of an initial (normal) vascular cambium, supernumerary cambia are initiated outside of the primary vascular cylinder. The initiation of the first supernumerary cambium takes place through approximately the number of nodes equal to the denominator of the phyllotactic fraction characterizing a given axis. At each node a segment of supernumerary cambium is initiated opposite the leaf traces supplying the leaf inserted at that node. The segments of differentiated cambium are preceded by regions of obliquely and anticlinally dividing cells. In the single juvenile axis studied supernumerary cambial segments also appear above the node to the cathodic side of the entering leaf traces, and opposite the medullary bundle immediately anodic to these traces. Vascular connections among the primary and supernumerary vascular cylinders occur between leaf insertions on the same orthostichy. The levels at which these connections occur vary among stems. The switch from ordinary to anomalous secondary growth may be caused by a change in tissue response to stimuli produced by leaves.

The inflorescence of Thalia geniculata is among the most complex in a family characterized by complex inflorescences. The main axis of the inflorescence bears primary bracts which subtend either enriching branches, in the enriching zone, or pairs of flowers, in the florescence. The enriching branches repeat the structure of the inflorescence as a whole, with the addition of two specialized bracts: a prophyll and an interphyll. The paired flowers of the Marantaceae are mirror images of each other. The first bract of the inflorescence is formed in the plane of distichy of the leaves. Subsequent bracts are formed slightly to one side of the apex, giving a one-sided distichous arrangement. On an enriching branch the sterile prophyll is formed adaxially, followed by a fertile, abaxial interphyll. The first bract following the interphyll lies in a plane approximately perpendicular to the plane of the prophyll and interphyll. With the second bract the alternating divergence angles of approximately 115 and 145° begin to be established. The paired flowers of the florescence are subtended by a single, adaxial prophyll. Unlike many other Marantaceae no interphyll or bracteoles are formed below the flowers.

There is a definite relationship between the phyllotactic fraction and the sympodia uniting median leaf traces in a stem. The denominator of the phyllotactic fraction is the number of sympodia in the stem, and the numerator is the number of sympodia counted in passing from the sympodium of one leaf to that of an adjacent leaf on the genetic helix. This relationship holds for species with closed as well as open vascular systems. Of the 100 shoots (93 species) whose vasculature has been reviewed from the literature only one shows no apparent relationship between the phyllotactic fraction and the vasculature. Shoots for 87 species show the relationship described above while shoots of five species have both irregular phyllotaxis and vasculature. The mathematical constraints on this relationship are shown to depend on the divergence angle and the fact that sympodia do not cross one another. That there are biological controls on this relationship in addition to the purely mathematical ones is shown by the fact that sympodial connections are almost universally made along orthostichies. These controls most likely operate on factors that influence the formation of orthostichies such as the relationship between leaf-shape and size of the apical dome.

Allometry was used to compare differential growth of the floral organs in seven species of the Marantaceae and in Canna indica. Different relative sizes of the floral parts arose through changes in the allometric growth rates, not by extension or truncation of the period of allometric growth. Cor-relations were found between the allometric growth rates of the various floral organs and the relative sizes of these organs. Relative size of the floral parts that function in pollination showed the best correlations with their growth rates, suggesting that selection for the relative sizes of floral organs can influence the allometric growth rates of these organs. Principal component analysis showed that growth rates of those floral members that function in pollination do not change independently. Two methods of pollinator action are suggested to account for this phenomenon. Similarity in allometric growth rates did not reflect the traditional taxonomic treatment of the Marantaceae at the generic level.

The paired flowers of all species of the Marantaceae studied, except Monotagma plurispicatum, are produced through the division of an apical meristem with a tunica-corpus structure. The solitary flowers of M. plurispicatum develop from a similar meristem which does not bifurcate. The paired flowers of Canna indica are produced in the axil of a florescence bract through the formation of a bract and an axillary flower on the side of the primordium which gives rise to the largest flower of the pair. The sequence of organ initiation for both families is: calyx, corolla and inner androecial whorl, outer androecial whorl, gynoecium. The sequence of sepal formation is opposite in the two families. In the Cannaceae it leads directly into the spiral ereated by the formation of the other organs, while in the Marantaceae the sequence of sepal formation follows a spiral opposite to that of the other floral organs. The members of the corolla and inner androecial whorl separate from common primordia. In general these common primordia sepa-rate into a petal and an inner androecial member through the initiation of two growth centers, at the same level, in the dorsal and ventral flanks of the primordium. In Ischnosiphon elegans and Pleiostachya pruinosa the stamen is initiated at a lower position than the petal in the ventral flank of the common primordium. A similar pattern of initiation is described for the callose staminode in Marantochloa purpurea and Canna indica. This pattern is interpreted as a variation on the more generalized pattern of inner androecial formation found in the other genera.