Lycopodiella inundata is a diploid and our two other species are tetraploid and suspected of being of hybrid origin. Lycopodiella margueritae is hypothesized to be derived from a hybrid of L. inundata and L. alopecuroides, while L. subappressa may be derived from L. inundata and L. appressa. Neither L. alopecuroides nor L. appressa, however, are now known from Michigan, nor are the primary (diploid) hybrids.
All species can occur in similar habitats, and may all occur together in southern Michigan. Where they do, hybrids of intermediate morphology are likely to occur. Hybrids between the diploid L. inundata and either tetraploid have large percentages of abortive spores and can be detected this way as well as by morphological intermediacy. Hybrids between the two tetraploids may be expected to produce mostly “good” spores and are poorly documented.
1. Horizontal stems less than 1 mm in diameter except at root nodes; horizontal stem leaves usually less than 6 mm long, teeth or bristles absent; erect shoots mostly less than 10 cm tall.
1. Horizontal stems 1–3 mm in diameter; horizontal stem leaves 4–13 mm long, bearing varying numbers of marginal teeth or bristles; tallest erect shoots often more than 10 cm tall.
2. Horizontal stems 1.0–1.7 (–2) mm in diameter; horizontal stem leaves usually 4–6 mm long, meeting the stem at an acute angle (upswept); strobilus (10–) 13–33 (–40) % of the total vertical shoot height.
2. Horizontal stems 1.8–2.2 (–3) mm in diameter; horizontal stem leaves usually 6–13 mm long, spreading (frequently perpendicular to the stem); strobilus 33–66 % of the total shoot height.
All species found in Lycopodiella
MICHIGAN FLORA ONLINE. A. A. Reznicek, E. G. Voss, & B. S. Walters. February 2011. University of Michigan. Web. October 19, 2017. http://michiganflora.net/genus.aspx?id=Lycopodiella.