Epilobium minutum
Epilobium suffruticosum
California willowherb, chaparral willowherb, desert willowherb, little willowherb, minute willowherb, small-flower willowherb
shrubby willowherb
strict, erect, sometimes reddish green, terete, 3.5–40 cm, simple or freely branched, subglabrous proximally to strigillose and glandular puberulent distally.
several–many, ascending to erect, terete, 10–25 cm, simple or well-branched, ± densely strigillose.
alternate distally, not fasciculate, petiole 0–2 mm, blade subspatulate proximally to lanceolate, oblanceolate, or narrowly elliptical distally, not folded along midrib, 0.9–2.5 × 0.2–0.6 cm, shorter than internodes, base tapered, margins entire or scarcely denticulate, 1–4 teeth per side, lateral veins obscure, apex subacute or often blunt proximally, surfaces subglabrous or with scattered hairs along margins;
bracts much reduced, sometimes attached to pedicel.
often crowded, opposite and sometimes with fascicles of very small leaves at proximal nodes, subsessile or attenuate to broad petiole 0.5–1.5 mm, blade light grayish green, narrowly lanceolate to elliptic, 1–2.5 × 0.2–0.7 cm, often exceeding internodes, base cuneate to attenuate, margins entire or ± denticulate, 4–6 low teeth per side, lateral veins inconspicuous, apex blunt proximally to subacute, surfaces ± densely short-strigillose;
bracts not much reduced in size.
erect racemes or open panicles, relatively loose and uncrowded, branches thin, mixed strigillose and glandular puberulent.
erect racemes or panicles, ± densely strigillose.
erect or, sometimes, nodding in bud;
buds broadly ovoid, 1.2–2.5 × 1–1.5 mm;
floral tube 1.1–1.5 × 1–1.4 mm, usually with ring of spreading hairs at mouth inside;
sepals 0.5–2.5 × 0.4–1.3 mm, apex acute, abaxial surface strigillose, sometimes mixed glandular puberulent;
petals white to pink, 2–5 × 1.5–3 mm, apical notch 0.2–1.9 mm;
filaments white, those of longer stamens 0.5–3 mm, those of shorter ones 0.3–2 mm;
anthers 0.6–1 × 0.5–0.8 mm;
ovary 4–9 mm, mixed strigillose and glandular puberulent;
style light pink, 1–3.5 mm, stigma subclavate to obscurely 4-lobed, 0.4–0.6 × 0.4–0.5 mm, surrounded by longer anthers.
slightly nodding;
buds 4–8 × 1.5–3.5 mm, apiculate;
floral tube funnelform to obconic, 1.8–3 × 1.9–2.6 mm, ring of spreading hairs 1–2.5 mm from base inside;
sepals 3–6.5 × 1–2.6 mm, often apiculate, abaxial surface densely strigillose;
petals cream to light yellow, obcordate, 5–9.3 × 2–3.8 mm, slightly unequal with upper 2 longer, apical notch 1–2.3 mm;
filaments cream, slightly inflated at base, those of longer stamens 6–10 mm, those of shorter ones 4.5–8 mm;
anthers cream-yellow, 1.4–2.2 × 0.6–1.1 mm;
ovary 4–9 mm, densely white-canescent;
style declined below main plane of flower, cream, 7.8–14.5 mm, glabrous, stigma deeply 4-lobed, 0.8–1.2 × 1.8–2.8 mm, lobes spreading-recurved 0.9–1.2 mm, exserted beyond longer anthers, often prematurely exserted and protogynous.
9–28 mm, surfaces strigillose and glandular puberulent;
pedicel 3–10 mm.
often curved, fusiform-clavate, 10–30 mm, surfaces finely strigillose;
pedicel 4.5–13 mm.
obovoid, without constriction, 0.9–1.2 × 0.4–0.6 mm, low chalazal collar 0.1–0.2 mm wide, brown, surface reticulate;
coma easily detached, white, 2.5–3 mm.
narrowly obovoid to oblanceoloid, with constriction 0.7–1.3 mm from micropylar end, 2.1–3 × 0.7–1.1 mm, very inconspicuous chalazal collar, light brown, surface low-papillose;
coma easily detached, tawny, 7–9.5 mm, with unusually dense hairs.
= 26.
= 30.
Epilobium minutum
Epilobium suffruticosum
Epilobium minutum, like the similar E. foliosum, also occasionally produces cleistogamous flowers, and is modally autogamous in any event. S. R. Seavey et al. (1977b) observed that E. minutum is less common than E. foliosum in the southern part of their overlapping ranges and more common in the north. Several sheets (for example, Lawler 3276, California, Butte Co. [MO]; Nelson & Gordon 5573, California, Trinity Co. [MO]) mention that the plants were growing on serpentine soil. The earliest collection of this species appears to be one made by Archibald Menzies in 1792–1794 under the name E. palustre (BM).
Crossostigma lindleyi Spach (a substitute name for Epilobium minutum) and E. lindleyi (Spach) Rydberg are illegitimate names that pertain here.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Epilobium suffruticosum shares its unusual cream-yellow flower color only with E. luteum, a distantly related species in sect. Epilobium. Both species have relatively large flowers with 4-lobed stigmas and are visited quite intensively by bees and other insect pollinators. Nevertheless, these species differ dramatically in habit, leaves, seeds, and many other characters, do not overlap at all in distribution, and are never confused with one another; the similar floral features must have been derived independently.
The flowers of Epilobium suffruticosum are also slightly zygomorphic, which is relatively rare in the genus. In the field and on many herbarium specimens of E. suffruticosum, the stigmas are clearly exserted even before the flowers are fully open. The label for Raven 26451 (Wyoming, Park County, MO) notes: “protogynous; in late bloom, most flowers male-sterile.” Several flowers from this collection have undeveloped anthers, suggesting that the flowers are functionally pistillate. However, these plants are not sterile since they have apparently fertile capsules with fully developed seeds.
The distribution of Epilobium suffruticosum consists of two clusters of fairly common occurrence—in northwestern Wyoming around Yellowstone and Teton national parks, and in south-central Idaho mainly in the drainages of the Boise and Payette rivers—with more scattered collections in western Montana north to Flathead County, and a single collection to the south in Weber County, northern Utah. There are no obvious morphological discontinuities among these specimens, nor any obvious explanation for the gaps in distribution; it may be due to collecting bias. This species is commonly found on gravel/sand bars of cold montane streams and rivers, in a stable association despite the apparent ephemeral nature of these habitats. It would appear that the plants have deep, woody roots by which they anchor themselves; in the spring flood stages of these rivers, they must experience complete inundation and considerable scouring, yet persist, often in moderately large colonies.
The exact locality of the type collection (streams east of Wallawallah, plains of the Upper Columbia River, Oregon) is problematic, since the closest known localities are at least 250 km southeast of the town of Walla Walla, Washington. Whether this is a matter of the historical accuracy of the locality by Nuttall or of the local extinction of this species from a locality in eastern Oregon cannot be determined at present. A collection by Hayden in 1859 (Powder River, Wyoming) is far outside the range of E. suffruticosum and may have been mislabeled.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
- Local floras:
BC, 
CA, 
OR, 
WA - Local Web sites: CalFlora, CalPhotos,
Flora NW, 
PNW Herbaria, Turner Photog. 
WildflowerSearch
iNaturalist (observations)
USDA Plants Database- LBJ Wildflower Center
- SEINet
- Plants of the World Online
- Encyclopedia of Life
- Wikipedia
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