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Phylum Lycophyta (or Lycopodophyta) -- club mosses or ground pines or lycopods
Lycophyta comprises only five or six extant genera (many more extinct taxa) of which three occur in Texas. Lycopodium is common in east Texas, Isoetes occurs on granite outcrops in the hill country; Selaginella occurs throughout the state, although some species are easily mistaken for mosses.

Lycopodium is homosporous--all spores are roughly equal in size. Selaginella and Isoetes are heterosporous--spores are of two distinct sizes, microspores and megaspores.

Genus Selaginella

Selaginella - a mesic or moisture-loving species
Most textbooks portray Selaginella as a delicate plant requiring constant moisture. Texas, however, is home to several species of Selaginella which thrive in desert.



Selaginella - a xeric species in its dormant condition
Selaginella - a xeric species after wetting

Selaginella strobilus, l.s., 20x



If a species' sporophytes produce two types of spores, the species is heterosporous.

Selaginella strobilus, dissection w.m., 20x

Selaginella strobilus, two types of sporangia
A mesic Selaginella with strobilus

Selaginella - a mesic species
This is not one leaf, it is a system of branching stems with many leaves (microphylls)

Selaginella - growing wild (Hawaii)

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