Comparative Studies of the Nodal and Vascular Anatomy in the Neotropical Cyatheaceae. I. Metaxya and Lophosoria

Abstract

Comparative studies of the nodal and vascular anatomy in the monotypic genera Metaxya and Lophosoria are discussed as they relate to the taxonomy and phylogeny of the Cyatheaceae. Both genera are distinctive and primitive with respect to habit, stem and petiole indument, stelar pattern, and nodal anatomy. Metaxya possesses a prostrate, dorsiventral rhizome, whereas a short, upright radial stem occurs in Lophosoria. Trichomes occur on the stems and leaf petioles of these genera. Both Metaxya and Lophosoria have a spiral phyllotaxy, and adventitious buds occur on the petiole bases. The stelar pattern is basically a siphonostele, although frequently a dictyostele is found in Lophosoria. Accessory bundles are lacking in both genera. A characteristic petiole pattern is found in these genera, with an increase in complexity from an undivided strand in Metaxya to the three-parted petiole pattern in Lophosoria. Data from nodal and vascular anatomy indicate that these taxa are distinct from the other genera in the Cyatheaceae and belong in an independent position at the base of the Cyatheoid line, although in some respects an affinity to members of the Dicksoniaceae is indicated.

Anatomical Studies of Sphaeropteris and Cnemidaria (Cyatheaceae)

“…Similar idioblasts have been reported for Lophosoria (Lucansky, 1982), the other squamate genera (Lucansky, 1976b(Lucansky, , 1977 and Dicksonia (Williams, 1925). Cortical bundles are a characteristic feature of the Cyatheaceae (Lucansky, 1974b, Ogura, 1972, and are not found in any other group of ferns. Cubical cells occur between these sclerified areas and the cortex in these species (Fig.…”

“…Schiitze (1906) called these idioblasts excretion containers, rath- gata. Cortical bundles undergo divisions and fusions, end blindly in the cortex, fuse with meristeles and leaf traces, or infrequently proceed directly to the petiole as a leaf trace (Lucansky 1974b). 9).…”

“…Plant materials were killed and fixed in formalin-acetic acid-alcohol (FAA) and sectioned on a macrotome (Lucansky, 1976a). Sections (slices) were partitioned into manageable sizes, dehydrated in a tertiary-butyl alcohol series and embedded in paraffin (Johansen, 1940).…”

“…In all species studied, numerous medullary bundles are scattered in the pith (Fig. Medullary bundles arise de novo in the pith (Ogura, 1927, Lucansky, 1974b or are separated from the leaf-gap margins (Godwin, 1932;Lucansky, 1976b divisions, end blindly in the pith, fuse with a meristele or leaf trace or proceed directly to the petiole as a leaf trace (Lucansky, 1974b;Lucansky & White, 1974;Adams, 1977). They have been found in the other squamate genera in the family (Lucansky, 1974b(Lucansky, , 1976b(Lucansky, , 1977Ogura, 1972), but are lacking in Metaxya and Lophosoria (Lucansky, 1974a(Lucansky, , 1982.…”

The developmental anatomy ofMetaxya rostrata(Filicales: Metaxyaceae)

“…Early in this century, both species were treated as species ofthe cyatheaceous genus Alsophila (Die Is, 1902). Other workers have noted that the two genera show similarities to the dicksonioid tree ferns, and thus possibly represent intermediates between the two major groups oftree ferns (Tryon, 1970;Lucansky, 1974a;Gastony, 1981). Other workers have noted that the two genera show similarities to the dicksonioid tree ferns, and thus possibly represent intermediates between the two major groups oftree ferns (Tryon, 1970;Lucansky, 1974a;Gastony, 1981).…”