Morphology of the Megagametophyte and the Embryo Sporophyte of Isoetes lithophila

Embryogeny and Reproductive Biology of Bothrodendrostrobus mundus (Lycopsida)

“…13). This is typical of megagametophytes described from other free-sporing heterosporous lycopods (Bruchmann, 1912;La Motte, 1933;Rauh and Falk, 1959;Brack-Hanes, 1978). A well-preserved megagametophyte showing archegonia has been described by McLean (1912) from Setosisporites praetextus f. minor.…”

Megagametophyte Development in the Chaloneriaceae Fam. Nov., Permineralized Paleozoic Isoetales (Lycopsida)

“…5). A similar configuration also characterizes Isoetes (CAMPBELL 1891;LA MOTTE 1933), Selaginella (LYON 1901), and the Carboniferous lycophytes described by GALTIER (1970) and BRACK-HANES (1978) 6), resembling closely some species of Selaginella (BRUCHMANN 1912) and Lepidodendron estonense (GALTIER 1970).…”

“…Assuming that the abortive spores retain the structure of earlier developmental stages, we may interpret the ontogenetic sequence of spore development. Variations in megagametophyte structure may also represent developmental stages in light of the similar structural variations that occur in ontogenetic sequences of extant heterosporous lycophytes (CAMPBELL 1891;LYON 1901;LA MOTTE 1933).…”

“…; distribution of nuclei prior to cellularization (LYON 1901;LA MOTTE 1933). Cellular megagametophytes, contained within the megaspores displaying a closed trilete, represent young specimens in which archegonia have not yet differentiated.…”

Etude structurale, fonctionnelle et métabolique du méristème apical jeune de l’Isoetes setacea

“…Sur la terre humide, dans les conditions de temperature du laboratoire, 2 a 3 semaines de culture sont nicessaires pour obtenir des sporophytes possedant deux feuilles visibles a I'oeil nu. Ce laps de temps est comparable B celui generalement donne dans la litterature (Lamotte 1933;Bierhorst 1971). En milieu aqueux, nutritif ou non, 4 a 8 jours de culture suffisent pour que des sporophytes a deux feuilles soient observable~.…”