Northern Prairie Wildlife Research Center
1. Epilobium ciliatum Raf.
Two subspecies occur in the northern Great Plains and they are distinguished as follows:
1a. subsp. ciliatum. Plants usually producing above-ground leafy rosettes in fall; cauline leaves narrowly lanceolate to narrowly ovate; inflorescence non-leafy, branched; petals white to pink, 1.5-5(8) mm long; seeds (0.6)0.8-1.2(1.5) mm long. Occasional in NE and perhaps s SD.
1b. subsp. glandulosum (Lehm.) Hoch & Raven. Plants usually producing reddish, subterranean turions with fleshy, imbricate leaves in the fall; cauline leaves broader; inflorescence mostly leafy, unbranched; petals pink to rose-purple, rarely white, 3.5-10(12) mm long; seeds 1.1-1.6(1.9) mm long. Common throughout. E. glandulosum Lehm. var. adenocaulon (Hausskn.) Fern., E. adenocaulon Hausskn.
Also reported for the Black Hills are three species similar to though apparently much less common than E. ciliatum: E. halleanum Hausskn., E. hornemannii Reichenb. and E. saximontanum. They may be distinguished from E. ciliatum and each other by the following key:
1 Plants clumped or cespitose, forming short, leafy, above-ground shoots at the base; stem decumbent to ascending at the base; leaves petiolate .................. E. hornemannii 1 Plants not clumped or only loosely clumped, forming sessile, leafy rosettes or fleshy turions; stem erect at the base; leaves sessile to occasionally petiolate. 2 Plants 0.3-19 dm tall, forming leafy rosettes or large, subterranean turions; seeds 0.8-1.6(1.9) mm long, longitudinally striate with hyaline crests or ridges but lacking distinct papillae ......... E. ciliatum 2 Plants 0.2-6 dm tall, lacking rosettes, forming only compact subterranean turions; seeds 1.1-1.6(1.8) mm long, distinctly papillate, the papillae often in longitudinal rows. 3 Leaves sessile, clasping, mostly narrowly ovate, denticulate; turions fleshy, elongate; capsules subsessile, appressed; seed collar conspicuous below the coma ........... E. saximontanum 3 Leaves petiolate or subsessile, not clasping, lanceolate or narrower, subentire or denticulate; turions compact, round; capsules on pedicels 0.8-3.8 cm long; seed collar inconspicuous ...... ....... E. halleanum