Aquatic and Wetland Vascular Plants of the Northern Great Plains

31. Onagraceae, the Evening Primrose Family

2. Epilobium L. -- Willow herb

3. Epilobium leptophyllum Raf. -- Narrow-leaved willow herb

Erect perennial 2-8 dm tall, usually simple from the base, branching above, densely puberulent upward with incurved hairs, producing filiform stolons at the base in late summer and autumn, the stolons usually reddish, with remote pairs of minute scales and terminating in ovoid, fleshy turions. Leaves usually opposite below and alternate above, sessile, linear to linear-lanceolate, gradually reduced upward, 1-6(7.5) cm long, 1-5(7) mm wide, usually densely puberulent with incurved hairs, acute to blunt-tipped, revolute, cuneate at the base. Floral tube 0.8-2 mm long; sepals ovate-lanceolate, acute, 1.5-4.5 mm long; petals white to pinkish, 3-7 mm long, notched; pedicels mostly 0.5-2 cm long. Capsules linear, 2.5-8 cm long; seeds 1-2.2 mm long, the coma white to tawny. Jul--Sep. Shores, stream banks, springs, fens, seepage areas and ditches, often in shallow water; common in the n part, less so s; (Que. to B.C., s to NC, OH, MO, KS, CO and WA). E. palustre L., in part.

E. palustre L., which is very similar to E. leptophyllum, is reported for Custer and Pennington Counties, SD. The two species are distinguished as follows:

1	Leaves linear to lanceolate or oblong, subglabrous to sparsely
	strigulose above; inflorescence often nodding in bud,
	eglandular ................. E. palustre

1	Leaves linear, rarely wider, densely strigulose above;
	inflorescence erect or nearly so, often with a mixture of
	strigulose and glandular hairs .......... E. leptophyllum

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