Epilobium saximontanum
Epilobium suffruticosum
glandular willowherb, Rocky Mountain willowherb, Rocky Mountain willowweed, épilobe des rocheuses
shrubby willowherb
erect, strict, terete, 4–55 cm, simple or well branched in age, subglabrous proximally to mixed strigillose and glandular puberulent distally, with raised strigillose lines decurrent from margins of petioles.
several–many, ascending to erect, terete, 10–25 cm, simple or well-branched, ± densely strigillose.
opposite proximal to inflorescence, alternate and reduced distally, often ± appressed, usually subsessile, rarely petiole 1–3 mm, often clasping;
blade obovate proximally to ovate, lanceolate, or narrowly elliptic distally, 1–5.5(–6.5) × 0.4–2(–2.4) cm, base rounded or obtuse, margins low denticulate, 9–30 teeth per side, veins ± conspicuous, 3–6 per side, apex subacute, surfaces subglabrous with strigillose margins;
bracts much reduced.
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, sometimes nodding in bud, racemes, sometimes sparsely branched.
erect racemes or panicles, ± densely strigillose.
erect;
buds 2–3.5 × 1.8–2.5 mm;
pedicel 0–1 mm;
floral tube 0.8–1.4 × 0.8–1.9 mm, ring of sparse spreading hairs at mouth inside;
sepals sometimes flushed red, 1.2–3.5 × 0.6–1.4 mm, abaxial surface strigillose and sometimes mixed glandular puberulent;
petals usually white, infrequently pink, 2.2–5(–7) × 1.7–3.2 mm, apical notch 0.4–1.5 mm;
filaments usually cream, rarely light pink, those of longer stamens 2–3.5 mm, those of shorter ones 1–2 mm;
anthers cream to light yellow, 0.3–0.8 × 0.3–0.5 mm;
ovary 9–30 mm, densely strigillose and glandular puberulent;
style cream or yellow, 1.6–2.8 mm, stigma usually narrowly to broadly clavate, rarely subcapitate, 1–3 × 0.8–2 mm, surrounded by at least 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.
30–55(–70) mm, surfaces mixed strigillose and glandular puberulent; usually subsessile, rarely pedicel 1–5 mm, often appressed to stem.
often curved, fusiform-clavate, 10–30 mm, surfaces finely strigillose;
pedicel 4.5–13 mm.
very narrowly obovoid, 1–1.6(–1.8) × 0.4–0.6 mm, chalazal collar 0.1–0.2 mm, light brown or gray, surface rugose to papillose;
coma usually readily detached, white, 3–9 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.
= 36.
= 30.
Epilobium saximontanum
Epilobium suffruticosum
Epilobium saximontanum is morphologically similar to E. ciliatum (especially subsp. glandulosum) with which it also shares the AA chromosome arrangement. However, in addition to its fleshy compact turions, it very characteristically has notably appressed capsules, unlike most other species in the genus, and a notably strict habit.
The distribution of Epilobium saximontanum is unusual; it includes the Rocky Mountain region, only barely reaching the high southern Sierra Nevada, disjunct to the Black Hills of South Dakota, and more widely in eastern Canada, from the shores of Hudson Bay to Newfoundland. Specimens are fairly uniform across this wide and rather discontinuous range, although locally they show some variability, possibly due to hybridization with any of several species that may be sympatric with it. H. Lewis and D. M. Moore (1962) reported hybrids between E. saximontanum (cited as E. brevistylum) and E. ciliatum subsp. ciliatum (cited as E. adenocaulon) from Colorado, and herbarium specimens with E. saximontanum and apparent hybrids are not uncommon.
(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.)
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