Lycopodium lagopus is a relatively rare species and is very similar to the much more common L. clavatum. Both species have erect, leafy stems arising at
intervals from horizontal (also
leafy) stems spreading along the surface, or beneath fallen
leaves, but not beneath the soil. The leaves spread from several
sides of the vertical stem, giving a round cross-section to the
branches (i.e. the branches are not conspicuously flattened in
appearance--see the Diphasiastrum species for example of
flattened branches). Spores are produced in sporangia located
only in specialized "strobili" or cone-like structures
at the ends of the leafy vertical stems. L. lagopus and L. clavatum are
separated from other species in this group by having a narrow
elongated stalk between the leafy stem and the strobilus,
and by the lack of conspicuous narrowings along the vertical stems,
called annular (or annual) constrictions--see L. annotinum for the alternative to both characters. L. lagopus and L. clavatum both have elongate, hairlike
tips to each leaf, unlike the leaves of all our other Lycopodium species. The much less common L. lagopus is distinguished by having only one strobilus per vertical stem, versus more than one strobilus per stem for L. clavatum. Another helpful character to help distinguish these two species is the number of lateral branches from each vertical stem. L. lagopus generally has 2 or 3 branches and L. clavatum has 3-6 branches. It is necessary to check these characters for many stems in a population to arrive at a conclusion, since occasional exceptions on a single stem may occur for either character.
Although Lycopodium lagopus is relatively rare in Wisconsin, it is not as rare as the distribution map indicates. Recent collections will add records for two sites in Marinette County and one in Brown County and it is likely that future field work will produce additional records.