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Montana Field Guide

Montana Field Guides

Linear-leaved Willowherb - Epilobium palustre var. gracile
Other Names:  Epilobium leptophyllum

Native Species

Global Rank: G5
State Rank: SNR

Agency Status
MNPS Threat Rank:

External Links

General Description
See species description.

Erect perennial herbs, often robust and rank, spreading by threadlike, nearly leafless epigeous stolons that terminate in compact fleshy turions. Stems erect, terete, 15-95 cm tall, simple to well branched in larger plants, covered throughout with dense incurved strigillose hairs, sometimes mixed with glandular ones on the inflorescence, lacking decurrent lines from the leaf bases. Leaves linear to very narrowly elliptic, 2-7.5 cm long, 0.15-0.7 cm wide, not much reduced in size on inflorescence, usually longer than internodes, densely strigillose-pubescent both sides, increasing up stem, sometimes revolute, subacute especially in upper pairs, subentire with inconspicuous lateral veins, subsessile, occasinally fascicled. Inflorescence erect, crowded, leafy. Flowers erect; floral tube 0.8-1.5 mm long, 1.2-1.8 mm wide, densely strigillose outside, with a ring of spreading hairs inside at the mouth; sepals 2.5-4.5 mm long, 0.9-1.3 mm wide, green, strigillose; petals 3.5-7 mm long, 1.6-4 mm wide, white to light pink, obcordate with apical notch 1-1.8 mm deep; anthers 0.6-0.9 mm wide, cream, filaments white or cream, unequal, 0.8-3.5 mm long, at least the longer stamens usually shedding pollen directly onto stigma; ovaries 12-18 mm long, densely white canescent, rarely with an admixture of gland-tipped hairs, on pedicels 5-12 mm long, style 2-3.8 mm long, deep cream, stigma cream, narrowly clavate, rarely exserted beyond stamens. Capsules 3.5-8 cm long, slender, canescent, on pedicels 1.5-3.5 cm long; seeds 1.5-2.2 mm long, 0.5-0.7 mm wide, attenuate, narrowly obovoid, densely papillose, chalazal collar sometimes quite pronounced, 0.2 mm or less long, coma (tuft of hairs) 6-8 mm long, dingy white, persistent (Hoch 1986, in Flora of the Great Plains).

Hoch's description is based on recognition of this taxon as a species, not subspecies.

Range Comments
Widespread across much of North America excluding the southeast (Kartesz 2009).

Marshes, seepage areas, and mesic disturbed sites (Hoch 1986).

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Citation for data on this website:
Linear-leaved Willowherb — Epilobium palustre var. gracile.  Montana Field Guide.  .  Retrieved on , from