This section is from the book "An Illustrated Flora Of The Northern United States, Canada And The British Possessions Vol1", by Nathaniel Lord Britton, Addison Brown. Also available from Amazon: An Illustrated Flora of the Northern United States, Canada and the British Possessions. 3 Volume Set..
Lycopodium Selago L. Sp. PL 1102. 1753.
Stems rigidly erect from a short slender curved base, several times dichotomous, the densely folia-ceous vertical branches forming mostly compact level-topped tufts 2'-6' high; leaves nearly or quite uniform, very numerous, crowded, more or less appressed, or at least ascending, narrowly deltoid-lanceolate or somewhat acicular from a broader base, shining, pale green or yellowish, usually entire, acute, those bearing the sporanges (below the summit) a little shorter but not differing otherwise; plant frequently gemmiparous in the axils of the upper leaves.
On rocks, Labrador and Greenland to Alaska, south to the mountains of Maine, New Hampshire, Vermont and northern New York, on the summits of the higher Alleghenies to North Carolina, and to Michigan and Washington. Also in Europe and Asia. Autumn. Upright Club-moss, Fir-moss, Tree-moss, Fox-feet.
Lycopodium lucidulum Michx. Fl. Bor. Am. 2: 284. 1803.
Stems rising 6'-10' from a curved or decumbent base, 1-3 times dichotomous, the branches forming a loose cluster of a few leafy vertical stems; leaves dark green, shining, wide-spreading or finally deflexed, acute, somewhat oblanceolate, broadest above the middle, there more or less erose-denticulate, tapering gradually to a narrower base, arranged in alternating zones of longer and shorter leaves, the latter more often bearing the sporanges, less denticulate, even entire; plant often gemmiparous, the gemmae early falling and giving rise to young plants.
In cold, damp woods, Newfoundland to British Columbia, south to South Carolina, Tennessee and Iowa. Ascends to nearly 5700 ft. in Virginia. Trailing evergreen, Moonfruit-pine. Aug.-Oct.
Lycopodium porophilum Lloyd & Underw. Bull. Torrey Club 27: 150. 1900.
Stems rising 2'-4 from a curved or decumbent base, 1-.3 times dichotomous, the branches forming a rather close tuft of densely leafy vertical stems; leaves spreading or somewhat deflexed, entire or minutely denticulate, arranged in alternating series of longer and shorter, the former linear to linear-lanceolate, slightly broader above the middle, alternate, the latter distinctly broadest at the base, gradually tapering to an acuminate apex, and more often bearing the sporanges; plant often gemmiparous.
On partially shaded rocks, apparently preferring sandstone, Wisconsin to Indiana and Alabama; probably of wider distribution.
Lycopodium inundatum L. Sp. PI. 1102. 1753.
Plants small, with simple or 1-2-forked horizontal prostrate or slightly arched slender, often lax, leafy stems; peduncles 3"-2 1/2' long, arising directly from the creeping stem, terminated by a slender spike 1/2'-1 1/2' long, or the spike rarely subsessile; leaves of the stem linear-lanceolate, acute, mostly entire, curved upward, those of the peduncle more slender, spreading; sporophyls similar to the sterile leaves but wider at the base (linear-deltoid), spreading, entire or sometimes toothed just above the base.
In sandy bogs, Newfoundland to Alaska, south and west to New Jersey, Pennsylvania, Illinois, Michigan. Idaho and Washington. Also in Europe and Asia. Slender elongate forms, mainly from New England, are known as the var. Bigelovii Tuck.; they indicate a possible transition into the next species.