Lycopodiophyta (Microphyllophyta). The Lycopodiaceae are terrestrial or epiphytic homosporous, protostelic vascular plants comprising about half a dozen genera and 300 species. The free-living sporophytic plant body is basically dichotomously branching, consisting of a rhizome with adventitious roots, and an aerial portion with numerous, closely spaced, mostly spirally disposed microphyllous leaves, each with a single vascular trace. Eusporagia are found on the upper surface of the microphylls, either in unmodified shoot axes or in compact strobili. The independent gametophytes are bisexual, and are either irregularly lobed photosynthetic masses, or subterranean, branching structures that lack chlorophyll and require a fungal symbiont. Multiflagellated sperm produced in an antheridium must travel through a film of water to reach the egg of an archegonium in order to initiate the zygote that may develop into the new sporophyte individual.

Each "thumbnail" image below is linked to a larger photograph.


Lycopodium venustulum, club moss. This is an example of a species that forms peduncled strobili consisting of fertile microphylls.
Lycopodium phyllanthum (Phlegmariurus phyllanthus), club moss. This species has the spore-bearing microphylls in differentiated strobili but no peduncles are produced. Immature, green eusporangia are near the top of the photo in the close-up of the strobilis. A few yellow to white, ripe sporangia are found below the green ones. Toward the bottom of the strobilus the sporangia have shed their spores and are collapsed.
Lycopodium serratum (Huperzia serratum). In this species the fertile and sterile microphylls are similar in appearance so that no distinct strobilus is formed. A large, yellowish, kidney-shaped eusporangium is seen at the base of each fertile microphyll in the lower photo.

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