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Leaves of representative taxa within the vanilloid clade of Orchidaceae were cleared and their venation patterns studied. Within subtribe Pogoniinae, Isotria and Pogonia exhibit a prominent reticulate venation pattern, although only Pogonia ophioglossoides is characterized by free vein endings. Within subtribe Vanillinae, all species of Epistephium , as well as the New Caledonian endemics, Eriaxis rigida and Clematepistephium smilacifolium , have reticulate-veined leaves that are characterized by numerous free vein endings. Leaves of most species of Vanilla exhibit a parallel-veined pattern stereotypical of monocots, although branched secondaries with free endings were observed in V. africana . Most members of subtribe Galeolinae are «saprophytes» with reduced bract-like leaves. Vascular bundles enter these leaf-homologues in a parallel manner, but quickly ramify throughout the tissue in an irregular manner. Leaf venation is used to hypothesize patterns of generic relationships within the vanilloid clade. Molecular evidence for phylogenetic relationships among angiosperms indicates that reticulate leaf venation has arisen independently in several unrelated monocot families, including the vanilloid Orchidaceae, perhaps by a similar evolutionary scenario.

A comprehensive study of the nodal and leaf anatomy of Bonnetiaceae was completed in order to provide evidence for evaluation in relation to systematics. Nodal anatomy is trilacunar, three-trace or unilacunar, one-trace. Basic leaf anatomical features of the family include: complete or incomplete medullated vascular cylinder in petiole; paracytic mature stomata with encircling ridges; large mucilaginous cells in the adaxial surface of mesophyll; periclinal divisions in upper surface layers; and discrete patches of phloem within the vascular bundles. Especially noteworthy is the presence in some genera of foliar vascular bundles enveloped by a sheath composed of two concentric regions, i.e., an inner region consisting of multiple layers of fibers and an outer specialized endodermis composed of thin-walled cells with Casparian strips. Leaves are variable with respect to lamina and cuticle thickness, relative amount and number of palisade and spongy layers, venation of lamina, and the presence or absence of sclereids and crystals in the mesophyll. A major feature in the evolution of Bonnetiaceae is development of a highly divergent, essentially parallel, leaf venation that is superficially similar to that of some monocotyledons and apparently unique among dicotyledons. Foliar anatomy provides important characters for the recognition of subgroups within Bonnetiaceae and is consistent with the segregation of Bonnetiaceae from Theaceae.

Summary was undertaken in an attempt to help clarify the relationships of the genus. Detailed descriptions of leaf, stem, nodal, wood, and floral anatomy are presented. Wood is characterized by a combination of solitary and grouped vessels with elements having few-barred scalariform perforation plates, imperforate tracheary elements with very reduced pit borders, exceptionally tall and broad hetero- cellular rays, and vasicentric axial parenchyma. Of special interest is the presence in Sanango of a very uncommon multilacunar nodal structure having split-lateral traces. Stems possess cortical vascular bundles. Leaf stomata are anisocytic and distributed in clusters on the undersurface of the lamina. Anatomical evidences suggest that Sanango is most closely related to the Scrophulariales, sharing many important features with the Gesneriaceae.

The comparative vegetative and reproductive morphology and anatomy of the endangered, monotypic, dicotyledonous genusMedusagyne was studied, and detailed descriptions of leaf, axis, nodal, wood, floral, pollen, fruit, and seed structure are presented. Overall, the genus has many specialized features, including the possession of extreme, habitat-related specializations. Flowers are either bisexual or staminate, and are interpreted as retaining some primitive aspects, such as many free parts spirally arranged on an elongate floral axis. One of the most salient structural features of the plant is the massive development of ensheathing fibrous elements around the vascular system of both vegetative and reproductive tissues. Diffuse foliar sclereids are absent. Particular attention is paid to the unusual multicarpellate, synovarial gynoecium and comparisons are made with theCaryocaraceae. The totality of morphological and anatomical evidence confirms the view thatMedusagyne is a very distinct and evolutionarily isolated genus, best treated as forming the monotypic familyMedusagynaceae. Observations are presented, including the occurrence of stamen fascicle traces, that link the family to the dillenialean and thealean assemblage. Like other isolated thealean taxa,Medusagyne shows affinities to several different families, without having especially close relationships with any particular extant taxon.

DICKISON, W. C. (Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 275993280) and A. L. WEITZMAN (Department of Botany, Smithsonian Institution, Washington, DC 20560). Floral morphology and anatomy of Bonnetiaceae. J. Torrey Bot. Soc. 125:268-286. 1998.-A detailed study of floral morphology and anatomy of three genera comprising a narrowly circumscribed dicotyledonous family Bonnetiaceae is presented. Flowers are subtended by bracteoles and possess a perianth that is clearly differentiated into a 5-parted calyx and corolla composed of rather thick members. The androecium contains numerous stamens that are united at the base to form a short tube or collar or the stamens are pentadelphous and grouped at the base into five bundles that are positioned in the petal planes. Stamen fascicle traces are reported for the first time in flowers of Bonnetiaceae and are shown to originate close to, or adnate to, the median petal trace. Occasionally, two fascicle bundles arise side by side from a common gap as double bundles. Anther morphology and attachment is variable. Ploiarium possesses nectariferous discs that alternate with the stamen clusters. The presence of nectariferous tissue in Archytaea is variable. Nectaries can be supplied by double bundles, supporting the view that the nectaries of Plioarium and Archytaea represent transformed stamens. Gynoecia are compound, superior, and 3-carpellate or 5-carpellate. Styles range from divided to the base to undivided, and uniformly have a papillate stigma and a central canal filled with transfusion tissue. Placentation changes from axile to essentially parietal at midlevel of the ovary. Ovules are bitegmic, and contrasted with the putatively closely related Theaceae in which the elongated inner integument forms the micropyle, the outer integument projects well beyond the inner one. In addition to the degree of style fusion and carpel number, other important differences among genera of Bonnetiaceae are found in anther wall structure and floral vascular patterns. Major features of variation in the floral vascular system relate to the number and degree of independence of sepallary and petal traces; degree of independence of the androecial vascularization; the organization of the central ovarian vascular system; and the condition of the stylar vasculature. Comparisons are made among the flowers of Bonnetiaceae, Theaceae and Cluisiaceae.

DIcIusON, W. C. (Department of Biology, University of North Carolina, Chapel Hill, NC 27599-3280). Morphology and anatomy of the flower and pollen of Saruma henryi Oliv., a phylogenetic relict of the Aristolochiaceae. Bull. Torrey Bot. Club 119: 392-400. 1992.-A study of the floral morphology and anatomy and pollen morphology of the monotypic Chinese genus Saruma was undertaken to provide a more thorough diagnosis of the plant and make comparisons with other members of the Aristolochiaceae. The possession of well-developed petals, a gynoecium of partially separate carpels, follicular fruit, and a monosulcate form of pollen document the primitive position of the genus. Pollen is semitectate and reticulate with a stratified, columellate wall structure. The gynoecium is of particular phylogenetic interest and is composed of a primitive form of three-trace carpel with an elongated, pubescent stigmatic region that extends along the exposed ventral (adaxial) surface. Numerous ovules are borne in two longitudinally oriented, submarginal rows and are vascularized by traces arising from the ventral bundles. The pattern of floral vascularization is similar to other members of the Aristolochiaceae, exhibiting the tendency for extensive fusion of vascular bundles. Unlike other Aristolochiaceae, oil cells and calcium oxalate crystals are absent from floral tissues. Saruma also diverges from the Aristolochiaceae by possessing stamens that become recurved inward at maturity, creating a functionally introrse dehiscence. Reproductive morphology provides compelling evidences for the segregation of Saruma to a distinct subfamily within the Aristolochiaceae. There is little convincing evidence to indicate that Saruma and Asarum share a common ancestry.

Further observations on the floral morphology and anatomy of the monotypic genusMedusagyne from the Seychelles are presented. The unique synovarious gynoecium is composed of numerous carpels that are attached to the side of a broad, elongated torus. The biovulate carpels are differentiated into a narrow ovary, a stout, erect, three-trace style, and a lobed, discoid stigma. The carpel wall is initially composed of thin-walled parenchyma, but at later stages of development the peripheral region becomes subdivided into many lignified sterile extensions. Carples show pronounced ontogenetic adaxial deformation, during which the upper ventral surfaces become expanded, greatly extending the ventral margins and forming a domelike cushion of carpel-derived tissue over the summit of the torus. The distal cushion remains separated from the flattened torus by a compressed cavity and eventually undergoes lignification, perhaps protecting the underlying gynoecium from chewing insects and exposure. Comparisons are made between the mature gynoecia ofMedusagyne and those of the genusDillenia. The occurrence of S-type sieve-element plastids inMedusagyne is reported for the first time, a feature in agreement with suggested thealean affinities of the family.

(...) Important and previously unreported differences between the two genera are: ovules bitegmic in Caryocar, ovules unitegmic in Anthodiscus; styles simple in Caryocar; styles compound in Anthodiscus; and major variation in floral vascularization including the more extensive fusion of major traces in Anthrodiscus. Stamen fascicle traces are reported for the first time in the family, and in combination with other features, clearly link the family to the Theales. (...)

A comprehensive anatomical study of the nodes and leaves of 21 species in five genera of Staphyleaceae was conducted to clarify the systematics and major trends of specialization and radiation within the family. The fundamenta staphyleaceous nodal pattern is trilacunar, three-trace, although a considerable range of variation exists within genera in numbers of traces and gaps and in the nature and course of individual traces. The nodes of most species of Euscaphis, Staphylea, and Turpinia have a distinctive nodal anatomy characterized by small accessory or subsidiary traces. Features of the lamina that show variation and are useful in generic and subfamilial delimitation include: mature stomatal type, mucilaginous and papillate epidermal cells, presence or absence of a hypodermis, presence or absence and type of vein sheathing, occurrence of domatia, and trichome type. Presumably calcium oxalate crystals of the druse or prismatic type occur in all taxa. The two subfamilies of Staphyleaceae are well defined...

Vegetative and reproductive anatomy and morphology are described for the first time for Tetracarpaea tasmannica Hook., a small shrub endemic to Tasmania. Tetracarpaea, a monotypic genus, has many characteristics of other woody Saxifragaceae, such as wood with solitary pores, scalariform perforation plates, sparse axial xylem parenchyma, tracheids, spiral thickenings in tracheary elements, and perforated ray cells. The tracheary elements of Tetracarpaea are much smaller than those characteristic of the Escallonioideae, a feature probably related to its montane forest habitat. Other features of Tetracarpaea inconsistent with most Escallonioideae include dark-staining deposits in the ray cells; a unilacunar, one-trace nodal pattern; lack of unicellular foliar trichomes; simple craspedodromous venation; areole development that is lacking or incomplete; straight and tapered veinlets; abaxial fibers associated with the foliar vascular bundles; and lack of bundle sheaths. The genus is further characterized by complete, hypogynous, tetramerous flowers. The essentially apocarpous gynoecium has multiovulate carpels, each supplied by three veins that reach the stigma. Ovules are anatropous, bitegmic, and crassinucellate. Lateral sepal bundles are derived either from the sepal midrib or from the petalplane bundles; stamens are supplied by independent traces or by bundles originating from compound traces in both sepal- and petal-planes. The follicular fruits possess a sclerenchymatous endocarp and contain winged seeds that have a membranous testa, a ridged surface, and a cellular endosperm. Reproductive morphological and anatomical features are more consistent with features of the Saxifragoideae than with the Escallonioideae or the Cunoniaceae, although the essentially apocarpous gynoecium with multiovulate carpels is not found in these groups. Vegetative and reproductive characteristics indicate that Tetracarpaea is more closely related to Saxifragaceae than to Cunoniaceae. It is possible this isolated genus should have separate familial status.

Developmental study of the stem-node-leaf vascular continuum of Austrobaileya scandens White reveals that the vasculature within each leaf originates from a single procambial strand, that becomes separated into two strands only at the junction of leaf and stem. At lower levels in the stem the two strands become incorporated into independent portions of the stele. At later stages of development the solitary vascular bundle within the young leaf undergoes considerable lateral growth, resulting in an essentially continuous arc of vascular tissue. Ontogenetic evidence indicates that the vascular bundle in the midrib of the lamina should be regarded as a fundamentally single bundle and not interpreted as two bundles that have undergone various degrees of secondary fusion. A condition of two totally separate bundles extending the entire length of the leaf was not encountered. Our observations confirm the characterization of Austrobaileya as an example of "second rank" level of leaf vasculature. Nodal anatomy emphasizes the extremely isolated taxonomic position of Austrobaileya within the primitive dicotyledons. THE DISCOVERY ofthe nodal anatomical pattern in which a unilacunar node is associated with two leaf traces, each related to an independent portion of the stem vascular cylinder, brought about a reassessment of ideas relating to the evolution of nodal vasculature in dicotyledons. Suggestions were made that the unilacunar, twotrace nodal condition was primitive in dicotyledons (Canright, 1955; Marsden and Bailey, 1955; Bailey, 1956). This idea was subsequently accepted by a number of individuals (Eames, 1961; Cronquist, 1968; Foster and Gifford, 1974). One of the primary evidences used in support of the primitive nature of the 2:1 node is its occurrence (or modifications thereof) in various members of the primitive Ranalean complex, including the monotypic family Aus

Five genera and 12 species of Staphyleaceae were examined with respect to systematic floral morphology and anatomy. Detailed descriptions of floral structure and vascularization are provided. Features of systematic and evolutionary importance in the family include the number and type of fusion of floral parts, placentation type, occurrence of a vascularized disk, and the degree of independence of floral vascular traces. Flowers of Tapiscia sinensis lack a disk, and the bicarpellate gynoecium, containing no internal ovarian septation, culminates a trend toward carpel fusion and reduction in ovular number that has resulted in a unilocular structure with a solitary ovule attached to a more derived basal or subbasal placenta. The progressive fusion of floral parts in the Staphyleaceae has been accompanied by the characteristic union of the androecial vascular supply and sepal-plane bundles, which subsequently divide to form an externally situated stamen vasculature and internal sepal strands. Huertea and Tapi...

A comprehensive study of nodal anatomy of the Cunoniaceae has revealed an unusually diverse assemblage of nodal types, including patterns with "split-lateral" traces previously undescribed for dicotyledons. On the basis of leaf arrangement and nodal vascularization, six distinct nodal conditions are recognized in the family. The trilacunar, three-trace pattern is the ancestral type from which the multilacunar condition evolved by amplification in the number of lateral traces. The "split-lateral" condition, distinguished by the fusion of lateral leaf traces of adjacent leaves, or the bifurcation of a single trace, and their association with a "common gap," probably evolved concomitant with the transition from opposite to whorled leaves. The characteristic interpetiolar stipules of the Cunoniaceae are vascularized by veins originating from lateral leaf traces, or by a combination of complete lateral traces and veins arising from lateral leaf traces. Both Aphanopetalum and Bauera possess unilacunar one-trace nodes. The most satisfactory family placement of both genera remains uncertain, although the unilacunar nodes of Bauera can reasonably be interpreted as a case of reduction from the trilacunar pattern in response to reduced plant size.

Pollen of 23 species representing all five genera was examined by light microscopy, scanning electron microscopy, and a selected number in transmission electron microscopy. For the most part the family is palynologically rather uniform with the occurring variation forming a morphological continuum. Staphyleaceae pollen is tricolporate, tectate, circular to triangular in outline in polar view and usually spheroidal. Ectoapertures are long to very long, recessed, and granular. Endoapertures range from poorly developed in Huertea and Tapiscia to well defined in Euscaphis, Slaphylea, and Turpinia, and are either bounded by the colpi margins or transversely extended. Periapertural exine thinnings are present. The exine is stratified into tectum, columellae, foot layer and endexine. The endexine is either smooth, or as in Slaphylea, solid near the foot layer and granular on the inner surface. Tapiscia is characterized by the absence of endexine and an interrupted fool layer. The exine surface is tectat...

The anatomy and morphology of vegetative and reproductive structures of the monotypic, dicotyledonous genus Oncotheca were studied to evaluate the svstematic relationships of this New Caledonian endemic. Wood has remained at a low level of advancement, as evidenced by the solitary, angular pores and exclusively scalariform perforation plates. Imperforate tracheary elements are fiber tracheids, and asial parenchyma is diffuse to diffuse in aggregates in distribution. Sieve tube elements possess oblique to very oblique, compound sieve plates. Nodal anatomy is pentalacunar, and petioles contain a single, undissec.ted arc of vascular tissue. A number of apparently xeromorphic leaf features, including general foliar coriaceousness, may result from the poor availability of soil minerals. Leaves are characterized by a thick cuticle, uniseriate epidermis with nearly anomocytic stomata having paracytic or tetracytic tendencies and a bifacial mesophyll with two or three hypodermal layers. Foliar venation is brochidodromous. Highorder venation is characterized by freely ending branched veinlets and imperfect areolation. Flowers are relatively advanced, as evidenced by extensive fusion of parts and the tlnion of major floral bundles such as the ventral carpellary traces. A c]ose relationship between Oncotheca and the Aquifoliaceae and Ebenaceae is refuted. Support is given to the elevation of the genus to familial status and its placement near the Theaceae.

sepals are vascularized by a single, undivided bundle. Petals, when present, and stamens, are uniformly one-trace structures. A general tendency exists within the family for the principal floral bundles to unite in various ways, with fusions evident between calyx, corolla, and androecial vascular supplies. Carpel number ranges from two to five and the gynoecium is generally surrounded by a prominent disc. Gynoecia of Ceratopetalum and Pullea are "halfinferior." The number of ovules per carpel locule ranges from one to numerous. Ventral carpel sutures range from open to completely sealed at the level of placentation. Carpels of the apocarpous genus Spiraeanthemum (incl. Acsmithia) are vascularized by a dorsal bundle and either three or four bundles constituting the ovular and wing vasculation in the ventral position, a condition unlike other members of the family. Ovules are supplied by the median ventral bundle. More advanced bicarpellate gynoecia within the family are predominately vascularized by a dorsal and two ventral bundles although a variable number of additional lateral wall traces may be present. A major trend exists toward fusion of the ventral bundles of adjacent carpels in the ovary of both bicarpellate and multicarpellate plants. At the base of the styles the fused ventral strands separate and extend along with the dorsal carpellary bundles into styles of adjacent carpels. In Pullea the ventral bundles terminate within the ovules. The united ventral carpellary bundles in Aphanopetalum, Gillbeea, and Aistopetalum lie in the plane of the septa separating adjacent carpels. Ovules are vascularized by traces originating from the vascular cylinder at the base of the gynoecium or by traces branching from the ventral bundles. Ovular traces in each carpel are united, or remain as discrete bundles, prior to entering the placenta. Tannin and druses are common throughout all floral parts. Although floral anatomy generally supports the position of Cunoniaceae near Saxifragaceae and Davidsoniaceae, the evolutionary relationship of the Cunoniaceae to the Dilleniaceae is uncertain. THE CUNONIACEAE is a family of woody dicotyledonous plants almost exclusively restricted to the Southern Hemisphere. Twenty-one genera currently recognized in the family are distributed in the Australian, New Guinean, and New Caledonian area. Belangera and Caldcluvia from South America, and Platylophus from South Africa, are the only genera found exclusively outside this general area. The family contains approximately 350 species, with about half this number belonging to the large and widely distributed genus Weinmannia (Schulze-Menz, 1964). The number of endemic and monotypic genera in the

A B S T R A C T Barbeya, a monotypic genus of dioecious, arborescent dicotyledonous plants from northeast Africa and adjacent Arabia, is usually regarded as having affinities within the Urticales. It is placed either in the Ulmaceae or segregated as a closely related, monotypic family. Leaves are opposite, exstipulate, and vascularized by a single, crescent-shaped trace from a unilacunar node. Wood anatomy indicates specialization at about the same level as other Urticales. Sieve tube elements of the secondary phloem exhibit highly oblique, compound sieve plates which indicate a low level of evolutionary advancement. The vascularity of the flower is described and compared with other Urticales. Pollen is tricolporate. The relationships of the genus to Moraceae, Ulmaceae, Urticaceae, and Eucommiaceae are discussed. The totality of anatomical and morphological evidence supports the retention of the family Barbeyaceae. BARBEYA is a monotypic, arborescent, dicotyledonous genus represented by B. oleoides Schweinfurth from the dry, mountainous regions of northeast Africa and adjacent Arabia. Although the plant was first reported and thoroughly

The secondary xylem of five species representing all three genera of Alseuosmiaceae was studied. Salient anatomical features that circumscribe the family include narrow vessel ele- ments with many-barred, scalariform perforation plates, pores distributed as a combination of both solitary elements and radial multiples, living septate fibers with stored starch at maturity, and the scarcity or absence of axial parenchyma. An absence of rays characterizes Alseuosmia and Wittsteinia vacciniacea. The insular species, W. balansae from New Caledonia, contains exclusively multiseriate rays that are very wide and tall and composed completely of erect and square cells. The large rays and the occasional scalariform lateral wall pitting of vessel elements of this species are probably best interpreted as paedomorphosis related to the increased size of this plant. The ancestral habit of the family remains unclear since Crispiloba disperma has retained a more primitive xylem structure as evidenced by the occurrence of axial parenchyma and shorter and narrower heterocellular rays. Xylem anatomy can be used to support a position for the Alseuosmiaceae in or near the woody Saxifragaceae.

A comprehensive study of floral and vegetative anatomy of the monotypic New Caledonian genusStrasburgeria Baillon was undertaken to provide a more thorough and accurate generic description, and to help clarify the evolutionary relationships of the plant. Detailed descriptions of leaf, stem, nodal, wood, floral, fruit, and seed morphology and anatomy are presented. In general, vegetative characters are primitive whereas those of the reproductive organs are regarded as advanced or specialized.Strasburgeria is envisioned as an early and independent offshoot from the thealean ancestral stock. It appears that the most appropriate treatment of the genus is to recognize the family Strasburgeriaceae and put it adjacent to the Ochnaceae in the current widely accepted manner.

A study of the floral anatomy and pollen morphology of both species of the endemic New Caledonian genusOncotheca was undertaken to provide a more thorough and accurate generic description and to make additional comparisons of the two species. In general, flowers of the species are histologically similar, althoughO. macrocarpa has a strong tendency to possess more numerous and widely distributed tanniferous cells and druses.Oncotheca macrocarpa also differs fromO. balansae in possessing the important feature of unfused ventral carpellary bundles. The unspecialized, 3-colporate pollen type of the two species is very similar in size and surface pattern, has clearly delineated wall layers, and is in harmony with the recent consensus opinion thatOncotheca is most closely related to the Theaceae and allies, although the genus is probably best interpreted as an isolated taxon linking the orders Theales, Ericales, and Celastrales.