Clubmoss
| Clubmosses: Lycopodiopsida | |
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| Lycopodiella cernua with close-up of branch | |
| Scientific classification | |
| Kingdom: | Plantae |
| Division: | Lycopodiophyta |
| Class: |
Lycopodiopsida Bartl. 1830 |
| Orders | |
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Lycopodiopsida is a class of herbaceous vascular plants known as the clubmosses and firmosses. They have dichotomously branching stems bearing simple leaves without ligules and reproduce by means of spores borne in sporangia at the bases of the leaves. Traditionally, the group also included the spikemosses (Selaginella and relatives) and the quillworts (Isoetes and relatives) but because these groups have leaves with ligules and reproduce using spores of two different sizes both are now placed into another class, Isoetopsida that also includes the extinct Lepidodendrales. These groups, together with the horsetails are often referred to informally as fern allies.
The class Lycopodiopsida as interpreted here contains a single living order, the Lycopodiales, and a single extinct order, the Drepanophycales.
The classification of this group has been unsettled in recent years and a consensus has yet to emerge. Older classifications took a very broad definition of the genus Lycopodium that included virtually all the species of Lycopodiales. The trend in recent years has been to define Lycopodium more narrowly and to classify the other species into several genera, an arrangement that has been supported by both morphological and molecular data and adopted in numerous revisions and flora treatments. Starting from the four genera accepted by Øllgaard, a study based on chloroplast DNA produced the cladogram shown below (reproduced here to genus level only), confirming the monophyly of the four genera, and their distance from Isoetes.
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