Leaves and stems:

Leaves may appear whorled or nearly so but are spirally arranged with 8 to 10 leaves in a cycle, more or less evenly spaced and may appear as 8 to 10 columns when viewed from the side of the stem (8 to 10-ranked) but not strongly so. Leaves are about ¼ inch (5 to 7 mm) long, to .7 mm wide, toothless, lance-linear pointed at the tip, bright green turning yellowish then light brown with age and eventually drop off (deciduous). 

Stems are horizontal, running above ground or just below the surface of the duff layer, but not underground. At fairly regular intervals, erect shoots emerge that are usually unbranched, but rarely will fork once. The erect shoots are up to 4 inches tall but usually shorter. Leaves on the erect shoots are mostly ascending and curved upward appearing somewhat appressed, while those on the horizontal stems are more spreading.

Spores:

Spores develop in spike-like structures called strobili. Strobili are single at shoot tips, ½ to 1½ inches long, and stalkless. Each tiny spore sac is attached to a scale (sporophyll) that is awl-shaped, broad at the base with an abrupt taper to a leaf-like extension at the tip. Scales are initially light green, turning yellowish as they mature and light brown when dry, then become more spreading to release the spores in late summer into fall.

Notes:

Northern Bog Clubmoss is a circumpolar species, occasional to common in open bogs and other wet places mostly in the northeast quadrant of Minnesota. It is among the species formerly all lumped into Lycopodium (L. inundata), which many references have now split into several genera and we have followed suit. Distinguishing characteristics of these groups are: whether spores develop in cone-like strobili or in leaf (or leaf-like) axils, whether strobili are stalked or stalkless, whether horizontal stems are above or below ground, whether branching on erect shoots is tree-like or not, the number of leaves in a spiral cycle, whether leaves are scale-like or not and whether they have a hair-like tip.

Northern Bog Clubmoss is the only Lycopodiella species known to be in Minnesota; it has stalkless strobili that are single at the tips of erect shoots, sporophylls are awl-shaped with a leaf-like tip, shoots are unbranched, horizontal stems are above ground, leaves are not scale-like, and number 8 to 10 in a spiral cycle and lack a hair-like tip. It is also the only clubmoss in Minnesota that does not have evergreen leaves and prefers open, wet habitat rather than drier forest. At a casual glance the spike-like strobili looks much like a thickened extension of the shoot stem, but on closer inspection the broad base of the sporophylls distinguishes them from true leaves.