Epilobium anagallidifolium
Epilobium obcordatum
alpine willow-herb, pimpernel willow-herb, épilobe à feuilles de mouron
heart willowweed, rock fringe, rockfringe willowherb, rose willowherb
many, ascending, often sigmoidally bent, nodding distally, later erect, clumped or mat-forming, terete, 3–20(–25) cm, simple, subglabrous, sometimes with faint raised strigillose lines decurrent from margins of petioles, rarely mixed strigillose and sparsely glandular puberulent distally.
many, decumbent to ascending, clumped or cespitose, green to grayish green, terete, 5–15 cm, branched mainly proximally, subglabrous and ± glaucous proximal to inflorescence, ± canescent distally or throughout.
opposite and crowded proximal to inflorescence, alternate distally, petioles 1–6 mm, rarely subsessile distally;
blade spatulate to oblong proximally, elliptic to narrowly lanceolate or sublinear distally, (0.5–)0.8–2.5 × 0.3–1 cm, base attenuate to cuneate, margins subentire proximally, sparsely denticulate distally with 2–5 low teeth per side, veins obscure, 2–4 per side, apex obtuse or rounded proximally to subacute distally, surfaces subglabrous;
bracts reduced, usually much narrower.
opposite proximal to inflorescence, alternate distally, usually crowded and exceeding internodes, subsessile or petiole 1–2 mm;
blade green or grayish green, usually broadly lanceolate-elliptic to ovate or obovate, rarely suborbiculate, 0.6–2.4 × 0.4–1.3(–1.9) cm, base rounded to subcordate, margins low denticulate, 4–9 teeth per side, veins indistinct, 4–7 per side, apex obtuse proximally to acute distally, surfaces usually subglabrous, rarely canescent, especially on margins and veins;
bracts much reduced.
nodding in bud, later suberect, few-flowered racemes, subglabrous to sparsely strigillose and/or glandular puberulent.
ascending to erect, sparse racemes or loose panicles, ± densely canescent and glandular puberulent.
suberect;
buds 2–5 × 1–2 mm;
pedicel 1–6(–15) mm;
floral tube 0.6–1.2 × 0.8–1.8 mm, slightly raised subglabrous ring at mouth inside;
sepals green to reddish purple, 1.5–5 × 0.6–1.5 mm, abaxial surface subglabrous to sparsely glandular;
petals usually pink to rose-purple, rarely white, narrowly obcordate, (1.7–)2.5–6.5(–8) × 1.6–3.5 mm, apical notch 0.5–1.2 mm;
filaments cream to light pink, those of longer stamens 1.4–3.2 mm, those of shorter ones 0.7–2 mm;
anthers 0.3–0.6 × 0.2–0.4 mm;
ovary often reddish purple, 6–20 mm, subglabrous or sparsely strigillose and glandular puberulent;
style white, 1.2–2.5 mm, glabrous, stigma broadly clavate to subcapitate, entire, 0.9–1.5 × 0.4–0.7 mm, surrounded by longer anthers.
erect;
buds 7–13 × 3–5 mm, apex acute, sometimes with stigma exserted;
pedicel 3–10 mm;
floral tube 3.2–5.5 × 2.2–4.2 mm, slightly raised ring of spreading hairs0.4–1 mm from base inside;
sepals (5–)8.5–14 ×1.8–2.9 mm;
petals pink to rose-purple, obcordate, (12–)15–26 × (7–)9–14.6 mm, apical notch 2.5–7.2 mm;
filaments cream to pink, those of longer stamens 8.5–16 mm, those of shorter ones 5.5–11 mm;
anthers cream-yellow, 1.6–2.9 × 0.6–1.3 mm;
ovary 9–22 mm, usually canescent and glandular puberulent, rarely subglabrous;
style cream to light pink, 11–23 mm, glabrous, stigma deeply 4-lobed, 1–1.5 × 2.2–4.5 mm, exserted beyond anthers.
slender, often reddish purple, 17–40(–55) mm, surfaces subglabrous or with scattered hairs;
pedicel 5–35(–68) mm.
straight, subclavate, 16–40 mm, surfaces canescent and glandular puberulent;
pedicel 5–15 mm.
narrowly obovoid, 0.7–1.4 × 0.3–0.5 mm, inconspicuous chalazal collar 0.1–0.2 mm wide, light brown, surface reticulate (smooth);
coma persistent, dull white, 2–4 mm.
narrowly obovoid, 1.4–2.1 × 0.6–0.9 mm, with low chalazal collar 0.4–0.5 mm wide, light or grayish brown, surface papillose;
coma easily detached, tawny, 5–9 mm.
= 36.
= 36.
Epilobium anagallidifolium
Epilobium obcordatum
Epilobium anagallidifolium is widely but sparsely distributed in high montane-alpine and subarctic Eurasia, including Europe, Russia, China, and Japan.
Epilobium anagallidifolium usually forms low clumps or mats, with stems nodding in bud and usually subglabrous below the inflorescence. Many collections of E. anagallidifolium from eastern Canada and Greenland tend to be unusually tall (to 25 cm) and robust for the species, with somewhat larger, thicker leaves, and longer pedicels (to 60 mm). Similarly large and robust specimens occur scattered in Yukon and Washington, and may result from occasional hybridization and introgression with sympatric species such as E. hornemannii or E. lactiflorum, which also have the CC chromosomal arrangement. In an analysis of Fennoscandian populations of the Alpinae group, I. Kytövuori (1972) found a similar pattern of mostly smaller, sigmoidal plants of E. anagallidifolium with a small proportion of larger ones, and he also suggested the possibility of hybridization and/or introgression.
Plants of Epilobium anagallidifolium, and indeed of the whole Alpinae group, from Haida Gwaii (the Queen Charlotte Islands) of British Columbia (J. A. Calder and R. L. Taylor 1968), are particularly distinctive compared to those on the mainland, and difficult to interpret. The observed differences may be the result of hybridization with other sympatric species or a response to unique ecological conditions on the islands, reinforced by relative isolation from mainland British Columbia.
The Linnaean name Epilobium alpinum has long been a source of nomenclatural confusion and instability, since it circumscribed at least four distinct species, especially E. anagallidifolium. A proposal by P. C. Hoch et al. (1995) to permanently reject the name E. alpinum Linnaeus was approved.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Epilobium obcordatum is an uncommon but relatively widespread and very characteristic species of the high Sierra Nevada, extending to scattered high ranges in northeastern Nevada, Idaho, and southeastern Oregon (Steens Mountains). Its low, clumped habit, dense green and often glaucous foliage, and large flowers make it one of the more attractive species of the genus, with considerable potential as a cultivated plant in rock gardens. Although it bears some general morphological similarities with two species in western North America, E. rigidum and E. siskiyouense, as discussed under those taxa, E. obcordatum also bears close resemblance to E. nankotaizanense Yamamoto, an alpine endemic from Taiwan, China (Chen C. J. et al. 1992). It is uncertain whether they are actually related or have evolved similar morphologies independently in similar high montane habitats on either side of the north Pacific.
Little has been reported on the pollination biology of Epilobium obcordatum, but its large flowers with marked protandry and herkogamy strongly suggest that the plants are outcrossing, probably pollinated by large bees.
Epilobium obcordatum shows considerable morphological variation, especially in leaf shape (ranging from narrowly ovate to orbiculate) and pubescence pattern. In the latter, plants mainly in the Sierra Nevada have stems glabrous and often glaucous below the inflorescence and mixed canescent and glandular puberulent distally. Plants mainly in Idaho and Nevada have stems sparsely to moderately canescent and inflorescences densely mixed canescent and glandular puberulent. But some collections, including the type of E. obcordatum var. puberulum, are mixed, and these pubescence differences do not correlate with other morphological or eco-geographical characters.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
- Local floras:
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OR, 
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Go Botany, 
PNW Herbaria, 
SW CO Wildflowers, Turner Photog. 
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USDA Plants Database- LBJ Wildflower Center
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