Comparative Studies of the Nodal and Vascular Anatomy in the Neotropical Cyatheaceae. Iii. Nodal and Petiole Patterns; Summary and Conclusions

Abstract

Comparative studies of the nodal and vascular anatomy in the Cyatheaceae are discussed as they relate to the taxonomy and phylogeny of the family. There is in the Cyatheaceae (excluding Metaxya and Lophosoria) a basic nodal pattern consisting of four major phases of leaf trace separations. Abaxial traces arise from the leaf gap margins, and the last abaxial traces from each side of the gap are larger and undergo numerous divisions. Distally adaxial traces separate from the gap margins, and the last adaxial traces are usually larger and undergo multiple divisions. In addition, medullary bundles frequently become petiole strands of the adaxial arc in the petiole. Rarely, cortical bundles form petiole strands in the abaxial arc in the petiole. Leaf gaps of the squamate genera of the Cyatheaceae are fusiform and possess prominent lateral constrictions which result from medullary bundle fusions and the separation of leaf traces. A characteristic petiole pattern is found in all members of the Cyatheaceae. There is an increase in the complexity of the petiole vascular tissue which results in a gradation from the undivided strand in Metaxya, to the three‐parted petiole pattern in Lophosoria, and finally to the much‐dissected petiole vascular tissue in the advanced genera. Nodal and vascular anatomy data basically support Tryon's phyletic scheme for the family. The Sphaeropteris‐Alsophila‐Nephelea line shows certain tendencies toward increased complexity of nodal and vascular anatomy, whereas the Trichipteris‐Cyathea‐Cnemidaria line shows the same anatomical and morphological characters in a direction of increased simplification or reduction.

Anatomical Studies of Cyathea and Trichipteris (Cyatheaceae)

“…Both genera are characterized by marginate petiole scales that lack apical setae, and the cellular differentiation of the scales is similar in both taxa. The stelar pattern in the mature stem is basically similar in both Trichipteris and Cyathea (Lucansky, 1974). In the species studied the stelar pattern is a dictyostele with overlapping leaf gaps and consists of individual meristeles, each surrounded by sclerenchymatous tissue ( Fig.…”

“…RESULTS AND DISCUSSION-Based upon habit, stem and petiole indument, stelar pattern, and the nodal anatomy of mature plants, Trichipteris and Cyathea show affinities and an evolutionary relationship (Tryon, 1970;Lucansky, 1974;Lucansky and White, 1974). Yet, comparative ana- 253 ALTHOUGH MORPHOLOGICAL similarities exist, Trichipteris (90 species) and Cyathea (11 0 species) represent separate evolutionary lines.…”

“…Previous anatomical studies have dealt primarily with mature paleotropical species (Bower, 1912;Ogura, 1927Ogura, , 1938Godwin, 1932;Mehra and Singh, 1955) and have shown that similarities occur in both the vascular anatomy and nodal patterns. Recent studies of mature members of the neotropical Cyatheaceae have also shown striking affinities between the squamate genera (Lucansky, 1974;Lucansky and White, 1974).…”

“…In the present study, cortical bundles occur only in the cortical zone of T. trichiata and form the conspicuous feature of this species. Only certain genera and species in the Cyatheaceae possess these vascular bundles (Lucansky, 1974). The cortical bundles of T. trichiata are large in size when compared with other genera in the family (Fig.…”

Phloem Anatomy of the Carboniferous Coenopterid Ferns Anachoropteris and Ankyropteris

“…Ogura (1972) discussed petiolar phloem in the ferns and described a range of bundle types from collateral to concentric. Although Ogura (1972) and other authors (Bertrand and Cornaille, 1902;Lin andDevol, 1977, 1978;Lucansky and White, 1974) have found that petiolar anatomy can sometimes be used as a taxonomic character, there are too many inconsistencies in the distribution of different types to utilize this character alone in constructing phylogenies. The petiolar trace in several Carboniferous ferns (e.g., Etapteris, Ankyropterist is radially symmetrical in transverse section, and thus cannot be compared to most extant filicaleans, which exhibit bilaterally symmetrical petiole traces.…”