Open AccessTeratisms in living and fossil megaspores of the Lycopsida: tetrad arrangement and exine ontogeny
Author(s) -
HEMSLEY ALAN R.
Publication year - 1997
Publication title -
botanical journal of the linnean society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.872
H-Index - 68
eISSN - 1095-8339
pISSN - 0024-4074
DOI - 10.1111/j.1095-8339.1997.tb02243.x
Subject(s) - biology , megaspore , tetrad , ontogeny , botany , microspore , evolutionary biology , pollen , paleontology , ovule , stamen , genetics
Abnormal megaspore tetrad configurations from Selaginella laevigata and of Lagenicula crass‐iaculeata (Lower Carboniferous) have been studied by SEM. These abnormalities reflect the variation expected in the presumed evolution of the seed‐plants from free‐sporing het‐erosporous ancestors. In addition, they indicate a possible role for the aborted members of a tetrad in the successful development and maturation of the functional spore(s). Aborted members of tetrads also reveal the later stages of the developmental sequence occurring in spore wall construction and highlight the interplay of sporopollenin production, its colloidal flocculation and polymerization, and distortion caused by protoplast expansion. Possible causes of abortion in both living and extinct lycopsid megaspores are discussed.