Trophophore stalk 2--15 cm, 0.8--1.2 times length of trophophore rachis; blade somewhat dull gray-green, plane, 3-pinnate, to 18 × 26 cm, herbaceous. Pinnae to 5 pairs, well separated, slightly descending to ascending, distance between 1st and 2d pinnae not or slightly more than between 2d and 3d pairs; basal pinnae remotely alternate and long-stalked (basal pinnae in all other botrychiums are opposite to subopposite and short-stalked), divided to tip. Pinnules ovate to fan-shaped, margins uniformly denticulate, apex rounded, venation like ribs of fan with short midrib. Sporophores 2-pinnate, 1.2--2.5 times length of trophophore. 2 n =180. Leaves green over winter, arising at variable times during last half of summer, meiosis as late as September. Woods and grassy places; 50--500 m; Ala., Fla., Ga., La., Miss., N.C., S.C., Tenn., Va.; West Indies in Greater Antilles. Botrychium jenmanii occurs in a variety of habitats. In hardwoods and especially pine woods, it is associated with B . biternatum ; in open grassy places and lawns it is found with B . lunarioides . In many ways, B . jenmanii is intermediate between B . biternatum and B . lunarioides , and it is possibly their allopolyploid derivative (W. H. Wagner Jr. 1968). It is the only tetraploid among New World members of subg. Sceptidrium .
Blade 3-4 times ternate-pinnate, with short, broad, flabellate, distally rounded and finely toothed ultimate segments; otherwise much like no. 5 [Botrychium multifidum (S. G. Gmel.) Rupr.]; 2n=180. Open woods, old fields, and pastures; W.I., n. to Va., Tenn., and Ala. Sept.-Nov. Rare.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.