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The hooded pitcher plant, Sarracenia minor, is a carnivorous facultative wetland species native to the southeastern USA and is listed as threatened by the state of Florida. Pitchers of S. minor possess white, semitranslucent spots (areoles), which have been hypothesized to aid in the capture of prey (= visual lures) by increasing the amount of light entering the back of the hood, which persuades insects to enter and fall into the base of the pitcher. In this study, the role of the areoles in prey capture abundance and diversity were experimentally investigated under variable lighting conditions in situ. Plants in two populations experiencing different light intensities, which varied in the amount of canopy cover and incident light reaching the plants, were experimentally manipulated by coloring varying percentages of areoles, ranging from 0 to 100 % (in increments of 25 %), with indelible ink. After 2 months, pitchers were collected and dissected to determine the number and identity of prey captured (approximately 18,000 prey were sampled). Although total prey abundance was approximately five times higher at McGirt’s Creek (sunny site) compared to UNF (shaded site), the effect of areoles on prey capture rates and biodiversity was site dependent. Reducing the number of visual lures of plants at the sunny site produced a significant decrease in the number of prey captured, but prey biodiversity (community composition) was unaffected. However, total prey capture was unaffected at the shaded site, while prey biodiversity was negatively correlated with the percent of areoles colored. Results from the current study suggest that areoles conditionally act as visual lures, but their overall importance is dependent on local environmental variables—especially canopy cover and the amount of incident sunlight reaching the plants.

The morphology and anatomy of the Backebergia militaris cephalium is characterized in comparison with its vegetative branch and with apical and lateral cephalia of other species. Our working hypothesis was that the B. militaris cephalium is more similar to the apical or lateral cephalia of other taxa than to its own vegetative branch. Our results revealed that the differences between the vegetative branch and the cephalium are primarily morphological: there is a change in the phyllotaxy, there are no interareolar spaces, making the ribs indistinguishable and abundant trichomes and bristles are produced in the areoles. In addition, a comparison between the vegetative branch and the cephalium shows differences in the epidermal cell size, thickness of the hypodermis and abundance of cortical bundles and mucilage cells. Unlike Melocactus intortus apical cephalia, B. militaris retains stomata in the epidermis and chlorenchyma, allowing the cephalium near the apical meristem to perform photosynthesis. The development of periderm in each areole after flowering and fruiting is a distinctive and defining feature of lateral and apical cephalia. In addition to early periderm development, the necrosis of cortical and pith parenchyma and fibers in secondary xylem and phloem in B. militaris distinguishes it from other cephalia described to date.

A comparative study of leaf architecture and anatomy of 42 species of Bernardia and other genera related of Acalyphoideae was undertaken to identify characters that support infrageneric and specific delimitation. Thirty variable foliar architectural and anatomical characters were studied. Some characters are consistent (e.g., venation pattern, secondary and tertiary vein arrangement, presence or absence of agrophic veins, type of areoles, bundle sheath cell type, presence or absence of fibers in the mesophyll, trichome type, stomata location, and type of crystals), and characterize genera. In addition, foliar character distribution within Bernardia supports the most recent infrageneric classification.

The morphology and anatomy of the Cephalocereus columna-trajani flowering region was described and compared with data on other species. The vegetative and reproductive regions were described in detail. The results showed that after the flowering region is differentiated, morphological changes take place which are correlated with anatomical changes. The flowering region in this species is termed a lateral cephalium because of its reduced interareolar space, increased areole size and abundant long bristles and trichomes in the areoles. Periderm development near the apical meristem, lack of chlorenchyma and a delay in xylem fiber differentiation are also traits characteristic of a lateral cephalium. The lateral cephalium of C. columna-trajani shared the same combination of morpho-anatomical characters with its sister taxon, C. senilis, except for the number of ribs in the cephalium. Both species survive in high temperature environments and their cephalium faces north; however, only C. columna-trajani tilts, thus we hypothesize that incorporation of fewer ribs associated with periderm development in the cephalium contributes to stem tilting.

Development of efficient in vitro propagation, systems for Pelecyphora aselliformis Ehrenberg and P. strobiliformis Werdermann, two endangered Mexican species of cacti, are described. Multiple shoot formation from areoles of in vitro-germinated plantlets was achived in two types of explants (apical and transversal) cultured in Murashige and Skoog (MS) basal media supplemented with 30 or 50 gl−1 sucrose, 10 gl−1 agar and various treatments with cytokins. Shoot production in these proliferation media was evaluated after one (60 d) and three (180 d) culture cycles. In P. asellifornis 13.7 shoots per explant were produced after the first cycle using apical explants in medium with 8.8 μM 6-benzylaminopurine (BA) and 30 gl−1 sucrose. In P. strobiliformis the highest proliferation rate (12.4 shoots per explant) was reached using 8.8 μM Ba and 50 gl−1 sucrose with shoot transverse segments as explants. After the third proliferation cycle, 128.1 and 136.3 shoots per explant were obtained in P. aselliformis and P. strobiliformis, respectively. The shoots were clongated in MS basal medium with 3 gl−1 activated charcoal and rooted in MS basal media indoleacetic acid (2.85 or 5.71 μM) or indolebutyric acid (2.46 or 4.90 μM). On averge, rooting efficiency was 89% for P. aselliformis and 87% for P. strobiliformis. The survival frequency, of the plants once transferred, to soil was on average 88%.

Leptocereus scopulophilus is newly described as endemic to the limestone summits and rocky hillsides of Somorrostro Hill, 25 km southeast of La Habana, Cuba. Since being discovered in 1923, it has been confused withLeptocereus leonii, from which it can be easily distinguished by its erect, ascending, branches which are greater in diameter and often 4–5 ribbed, by the more prominent and less crenate ribs bearing more widely spaced areoles and longer spines, and by its larger flowers with exserted stigma lobes and nearly tubular, green, spiny receptacles. The fruits also differ in being larger and in bearing clusters of persistent spines at maturity.

Venation pattern has been studied in 23 species of the genusCassia Linn. growing in India and these include the species that range in habit from prostrate, erect, shrubs, undershrubs to tall trees upto 10–15 m in height. The venation pattern shows a clear gradation of thickness upto the veinlets of the 6th category and in the size of areoles. Venation pattern and the presence or absence of areoles help to separate one species from the other on the one hand and correlate to the habit of species on the other.

The palmately compound leaf ofTabebuia pentaphylla is initiated by periclinal division in the hypodermal layer at the flank of the maximal shoot apex, which lacks cytohistological zonation. The growth of the leaf primordium is diffuse until it reaches a height of 50–60 μm after which an adaxial meristem makes it conspicuously thick at the basal region. The first pair of lateral leaflets arise about 50 μm below the tip of the leaf primordium when the latter is about 150 μm high and before the differentiation of a well defined marginal meristem. The second pair of leaflets arises subsequently below the first. The terminal portion becomes the central leaflet. The sites of leaflet initiation are the terminal endings of acropetally differentiating procambial strands. The 6-layered plate meristem of the leaflet lamina arises from a marginal meristem whose submarginal initial is wedge shaped. Leaflet venation is comptodromous and the ultimate areoles lack free vein endings.

Leaf architectural pattern has been studied in 27 genera and 35 species of the Acanthaceae. The major venation pattern conforms to pinnate camptodromous with eucamptodromous or festooned brochidodromous secondaries, pinnate craspedodromous inAcanthus ilicifolius and acrodromous inLepidagathis trinervis. Intersecondary veins are common. The marginal ultimate venation is looped. The areoles are variable in size. The vein endings are usually simple, linear or cuved or divide once or twice dichotomously. Isolated vein endings, tracheids, isolated free vein endings and extension cells are observed. Transfusion tracheids are seen inDicliptera verticillata. Miniature vessel elements with simple perforation plates are noticed lying free in the areole or at the end of tracheids inSeriocalyx scaber andThunbergia grandiflora.Elytraria acaulis, Nelsonia canescens andStaurogynae zeylanica exhibit venation pattern shown by majority of the taxa studied, of the Acanthaceae.

Young leaves of Cucurbita pepo L. were examined by whole-leaf autoradiography and serial paradermal sections were examined by light microscopy to determine whether commencement of sugar export depends upon the minor vein phloem achieving structural maturity. Maturation of these veins develops progressively from the largest toward the smallest elements with the minor veins in the distal region of the leaf maturing before those in the proximal region. Commencement of sugar export is coincident with maturation of the abaxial phloem of the minor veins delimiting the areoles. The abaxial phloem elements of the larger minor veins, which are probably capable of vein loading too but border only relatively few areoles, mature before export starts. The adaxial phloem surrounding the areoles and the xylem elements, mature in advance of the abaxial phloem and well before the beginning of sugar export. It is therefore considered unlikely that structural development alone directly governs the initiation of export. The results suggest that some other rate controlling step is involved.

The leaf architectural pattern in 6 species ofTamarix and two species ofMyricaria has been investigated. The leaves are simple, alternate and sessile. InTamarix aphylla, Tamarix dioica, Tamarix gracilis andTamarix troupii the leaves are completely or partially sheathing. In these species only the primary vein is distinguishable, the secondaries and the further orders of venation being not distinguishable from one another. In the other two species ofTamarix and inMyricaria the major venation pattern is pinnatecamptodromous type. The intercostal venation is of random reticulate type, and the marginal ultimate venation is incomplete. The areoles are polygonal to irregular in outline and randomly oriented. They may contain one or more veinlets or none. There is no direct correlation between the size of an areole and the number of vein endings. Hence, these characters cannot be said to be taxonomically significant as far as the species ofTamarix andMyricaria are concerned.

The leaf architecture has been studied in 19 genera and 35 species of the Brassicaceae. The major venation pattern is pinnate craspedodromous with the exception ofAlyssum maritimum, Iberis amara, I. umbellata andMalcolmia maritima where it is pinnate-festooned brochidodromous. The number of secondary veins and their angle of divergence vary from species to species and even within the same species. Marginal ultimate venation is mostly looped occasionally incomplete. The areole size and shape is variable. The veinlets may be simple or once or twice dichotomously divided. The simple veinlets may be curved or hooked. The tracheids are either uni-, bi-, tri- or multiseriate and extraordinarily variable in size and shape. Isolated vein endings, isolated free vein endings, isolated tracheids and extension cells are observed. Myrosin cells have been observed inEruca vesicaria ssp.sativa andCochlearia cochlearioides.

The development of the bovine muzzle has been studied in 43 foetuses and 5 young calves by morphometric, histological and histochemical methods, in order to clarify the morphogenetic events controlling the formation of the papillary body and cutaneous areoles of this region. In early foetuses the outer epidermis surface and dermo-epidermal boundary are smooth. Subsequently, due to differential growth in limited and neighbouring regions, hemispheric dermal bulges protrude towards the epidermis (primary dermal papillae). At later stages of development, a number of conical secondary papillae are seen to arise at the surface of the primary dermal ones in regular array, concentrically to the axis of the dermal primary papillae.

The venation system of the leaf inPolyalthia is pinnate. The procambial precursors of the vein in the leaves originate in the elongated cells of the middle layer, which in turn owes its origin to the adaxial hypodermal layer middle layer, which in turn owes its origin to the adaxial hypodermal layer of cells during the marginal growth of the leaf. Secondary vein development proceeds from the midrib to the margin of the leaf and from base to the apex. The plate-meristem is composed of isodiametric cells at the time of formation of secondary veins. At inception, the secondary vein procambium is multiseriate generally. The development of the tertiary vein procambium is mostly simultaneous and sometimes progressive and differentiates as uni- or biseriate strips. The quarternary vein and minor vein procambium differentiates as mostly uniseriate strips simultaneously. The vein endings, which are simple and unbranched contain only xylary cells, and develop progressively. The interveinal parenchyma possesses the capacity to produce additional procambial strands for a considerable period in ontogeny. Each areole contains one or two vein-endings, which end in the neighbourhood of the oil cells.

Leaf architecture including venation pattern has been studied in 19 genera and 29 species of the Apocynaceae. The leaves are simple, alternate, opposite or whorled with entire margin and a simple midrib. The major venation pattern conforms to pinnate camptodromous type with festooned brochidodromous secondaries. The qualitative and quantitative features are charted. The leaf size, areole size, number of vein endings entering the areoles and number of vein terminations entering the areoles vary from species to species even within the same species. The highest degree of vein order is observed up to 7°. Isolated tracheids, isolated vein endings, isolated free vein endings and tracheoidal elements are noticed. Bundle sheath cells ensheaths all category of veins.