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FNA | Family List | FNA Vol. 10 | Onagraceae | Epilobium

37. Epilobium howellii Hoch, Phytologia. 73: 460. 1993.

Yuba Pass willowherb

Herbs with short, threadlike stolons with scattered, minute leaves. Stems delicate, erect, loosely clumped, terete, 5–20 cm, simple or branched from base, densely glandular puberulent, without decurrent lines. Leaves opposite proximal to inflo­rescence, alternate distally, sub­sessile; blade broadly obovate to orbiculate proximally to ovate or lanceolate distally, 0.4–2 × 0.3–1.2 cm, base cuneate to rounded, margins finely denticulate, 4–6 low teeth per side, veins indistinct, 2–6 per side, apex obtuse to subacute distally, surfaces subglabrous with strigillose margins and veins or both surfaces sparsely strigillose distally; bracts much reduced and narrower. Inflorescences erect, open racemes, glandular puber­ulent. Flowers sometimes cleistogamous; buds 2–3.5 × 1–1.5 mm, often nodding; pedicel 8–16 mm; floral tube 0.4–0.8 × 0.5–1 mm, ring of sparse hairs at mouth inside, or absent; sepals 1.5–2 × 0.8–1 mm; petals white, 2–3 × 1.5–2 mm, apical notch 0.4–0.5 mm; filaments white, those of longer stamens 1.8–3 mm, those of shorter ones 1–1.5 mm; anthers 0.3–0.4 ×0.3–0.4 mm; ovary 9–12 mm, sparsely glandular puber­ulent; style white, 2–3 mm, stigma white, narrowly clavate, entire, 0.5–0.6 × 0.4–0.5 mm, surrounded by anthers. Capsules 35–45 mm, surfaces subglabrous to sparsely glandular puberulent; pedicel 25–40 mm. Seeds narrowly oblanceoloid, 0.8–1.1 × 0.3–0.4 mm, chalazal collar inconspicuous, surface low papillose; coma easily detached, dingy white, 3–6 mm. 2n = 36.

Flowering Jul–Aug. Mossy seeps, semi-shaded swales, grassy montane meadows; 2000–2700 m; Calif.

Epilobium howellii is an enigmatic species in that it was apparently overlooked until relatively recently by numerous botanists in the Sierra Nevada in Fresno, Mono, and Sierra counties. Its similarity to many of the smaller species of Epilobium, especially in the Alpinae group, may have caused this oversight; it is very clearly distinguished from similar species by its exclusively glandular puberulent stems. Recent focused collecting efforts mainly by United States Forest Service personnel have shown that it is much more widespread than originally thought, although still uncommon, and its geographical and ecological range is still quite restricted compared to most other species of Epilobium.


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