Confocal Microscopy Image Gallery
Plant Tissue Autofluorescence Gallery
Clubmoss Mature Stem
The life cycle of the clubmoss consists of alternating generations of familiar spore-producing plants and inconspicuous underground gametophytes. Clubmoss sporophytes often exhibit creeping or prostate stems, sometimes located underground, but certain species possess erect stems.
The stems are almost always heavily branched and thickly covered with small, needle- or scale-like green leaves. The spore-bearing leaves of clubmosses are typically organized into strobili, but a few members of the genus Lycopodium, including the shining clubmoss (L. lucidulum) native to North America, bear sporangia at the bases of leaves that are spread out rather than clumped together into cone-like structures. Clubmoss sporangia contain a single type of spore, which when released may quickly develop into a subterranean prothallium.
As is characteristic of gametophytes, the clubmoss prothallium enables sexual reproduction. Each clubmoss gametophyte holds both male antheridia and female archegonia. The gametophytes of various species may differ somewhat, but the stag’s horn moss (L. clavatum) is a standard example. The stag’s horn moss prothallium is small and saucer-shaped, and obtains its nutrients through a close relationship with saprotrophic mycorrhizal fungi. Multiple seasons may pass before the prothallium produces the next generation of sporophytes following the union of male and female gametes.
Nathan S. Claxton, Shannon H. Neaves, and Michael W. Davidson - National High Magnetic Field Laboratory, 1800 East Paul Dirac Dr., The Florida State University, Tallahassee, Florida, 32310.