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Lycopodiella

Species of Lycopodiella hybridize more frequently than other clubmosses in the region. With the exception of L. inundata, it is uncommon to find populations lacking hybrids, even when only one species is present. Sporophyll orientation is a very important character, but it cannot be assessed until late summer. Developing strobili have ascending sporophylls that eventually spread from the axis at maturity (except in L. appressa). Abortive-spored plants are present in New England, and not all circumstances appear to be explainable by differences in ploidy level. Reference: Bruce (1975).

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L. inundata
1a. Horizontal shoots, excluding the trophophylls, very slender, 0.5–0.9 mm thick, each segment producing 1 (rarely 2) upright shoot; trophophylls of the horizontal shoot entire; upright shoots rarely taller than 10 cm
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1b. Horizontal shoots thicker, 1.2–3.1 mm thick, each segment producing 1–5 upright shoots; trophophylls of the horizontal shoot toothed; upright shoots usually taller than 10 cm   [Figs. 13,14]
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  L. alopecuroides
  2a. Horizontal shoots prominently arching over the substrate, rooting 7.5–36 cm distal to the most proximal upright shoot [Fig. 13]; sporophylls 5.5–9 mm long, spreading at maturity, with 1–3 slender teeth on each margin
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  L. appressa
  2b. Horizontal shoots prostrate, rooting 1.5–4.8 cm distal to the most proximal upright shoot [Fig. 14]; sporophylls 2.9–5 (–5.2) mm long, appressed, entire or rarely with a low tooth on one margin

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