Comparative Ontogenetic Studies in Young Sporophytes of Tree Ferns. I. A Primitive and an Advanced Taxon

Abstract

Ontogenetic studies of young sporophytes were undertaken to determine anatomical and morphological differences between a primitive (Lophosoria quadripinnata) and an advanced (Sphaeropteris elongata) tree fern. In both species the first leaf is simple, fanshaped, and possesses dichotomous venation. Later‐formed leaves exhibit either a pinnate or bipinnate pattern of laminar dissection. As the sporophyte matures, the stelar pattern changes from a protostele to an amphiphloic siphonostele, and finally to a dictyostele in Sphaeropteris. Medullation of the protostele occurs either prior to or after the formation of the first leaf trace in both species. Differentiation of xylem in the shoot is acropetal and the appearance of mature protoxylem occurs closer to the apical meristem in Sphaeropteris. The nodal pattern varies within each species with a no gap 1‐trace pattern characteristic for the first two or three leaves, depending upon the taxon. In Lophosoria subsequent leaves possess a unilacunar 1‐trace nodal pattern, whereas a complete nodal series (1 gap 1‐trace to 1 gap 6‐trace) occurs in Sphaeropteris. Fusiform leaf gaps are noted in both species. The shoot apical meristem is dominated by a single apical cell, with an organized apical cell first found in P2. Stem, root, and petiole anatomy are discussed.

Desenvolvimento de Adiantopsis radiata, Pteris denticulata (Pteridaceae) e Polypodium latipes (Polypodiaceae) em condições naturais

“…Esse mesmo tipo de folha tem sido observado em esporófitos jovens de pteridófitas arborescentes (Stephenson 1907;Lucansky & White 1976), emAthyrium esculentum Cop. (Nayar 1960), em espécies de Blechnum (Rodrigues Rios 1973), de Bolbitis (Hennipman 1977), em Plagiogyria fialhoi (Windisch & Pereira-Noronha 1983), dentre outras.…”