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glandular willowherb, Rocky Mountain willowherb, Rocky Mountain willowweed, épilobe des rocheuses

clavatefruit willowherb, club willowherb, club-fruit willowherb, club-pod willowherb, talus willow-herb

Habit Herbs usually with sessile, fleshy, underground turions, or sometimes thick, elongated shoots with dark, decussate scales. Herbs with wiry, scaly soboles just below ground level, often with extended semi-woody rootstock.
Stems

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.

numerous, ascending, clumped, terete, 5–15(–22) cm, usually simple, rarely branched, subglabrous, with raised strigillose lines decurrent from petioles, ± densely strigillose and often mixed glandular puberulent distally.

Leaves

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.

crowded and opposite proximal to inflorescence, alternate distally, petiole 0–3 mm;

blade obovate proximally to ovate or elliptic distally, 0.5–2.8 ×0.6–1.6 cm, base attenuate proximally to obtuse distally, margins subentire to sparsely denticulate, 3–6 teeth per side, veins obscure, 2–4 per side, apex obtuse proximally to subacute distally, surfaces subglabrous or sparsely strigillose margins and abaxial midrib, sometimes subglaucous;

bracts not much reduced, sessile.

Inflorescences

erect, sometimes nodding in bud, racemes, sometimes sparsely branched.

usually erect, rarely slightly nodding, racemes, strigillose and glandular puberulent, sometimes sparsely so.

Flowers

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.

erect;

buds often purplish green, 3–4.5 × 1.4–2.2 mm;

pedicel 3–9 mm;

floral tube 0.6–2 × 1–2 mm, glabrous or with a raised ring of sparse hairs at mouth inside;

sepals often purplish green, 2.5–4.2 × 1–2 mm, abaxial surface sparsely glandular puberulent to subglabrous;

petals rose-purple to pale pink, obcordate, 3.5–6(–7) ×2–4 mm, apical notch 0.5–1 mm;

filaments cream, those of longer stamens 1.8–4 mm, those of shorter ones 1–3 mm;

anthers light yellow, 0.4–0.9 × 0.25–0.5 mm;

ovary often reddish purple, 8–20 mm, densely glandular puberulent, often mixed strigillose, rarely subglabrous;

style white or pale pink, 1.4–3.2 mm, glabrous, stigma cream, narrowly clavate to subcapitate, 0.8–1.4 × 0.3–0.8 mm, surrounded by at least longer anthers.

Capsules

30–55(–70) mm, surfaces mixed strigillose and glandular puberulent; usually subsessile, rarely pedicel 1–5 mm, often appressed to stem.

often purplish red, 20–42 mm, surfaces sparsely pubescent or subglabrous;

pedicel 2–21 mm.

Seeds

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 or fusiform, (1.3–)1.5–2.1 × 0.4–0.7 mm, chalazal collar conspicuous, 0.04–0.16 × 0.2–0.4 mm, blond, surface finely reticulate;

coma easily detached, white, 5–8 mm.

2n

= 36.

= 36.

Epilobium saximontanum

Epilobium clavatum

Phenology Flowering Jul–Sep. Flowering May–Sep.
Habitat Montane semi-shaded stream banks, damp meadows, mossy seeps, wet slatey cliffs, disturbed or seasonally damp areas. Rocky crevices, scree slopes, ledges, stream banks, often near snow banks or moraines in upper montane to alpine zones.
Elevation 0–3700 m. (0–12100 ft.) 800–4200 m. (2600–13800 ft.)
Distribution
from FNA
AZ; CA; CO; ID; MT; NM; NV; OR; SD; UT; WY; AB; BC; MB; NF; ON; QC
[WildflowerSearch map]
[BONAP county map]
from FNA
AK; CA; CO; ID; MT; NV; OR; UT; WA; WY; AB; BC; NT; YT
[WildflowerSearch map]
[BONAP county map]
Discussion

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 clavatum shares a clumped habit and the CC chromosomal arrangement with related species in the Alpinae group, but differs from them by its dense, wiry mass of basal soboles arising from an extended and somewhat woody caudex and relatively thick capsules and large seeds (1.3–2 mm). This unusual habit morphology may be the result of growing on unstable, shifting scree slopes. Like E. anagallidifolium, with which it often grows in near-sympatry in alpine areas, it is of notably low stature, often less than 15 cm, and has subentire leaves and capsules rarely exceeding 4 cm. However, E. clavatum does not nod in bud, and generally is more robust than E. anagallidifolium, and it has a much smaller range, being endemic only to the western North American cordilleran region, whereas E. anagallidifolium has a discontinuous circumboreal range.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source FNA vol. 10. FNA vol. 10.
Parent taxa Onagraceae > subfam. Onagroideae > tribe Epilobieae > Epilobium > sect. Epilobium Onagraceae > subfam. Onagroideae > tribe Epilobieae > Epilobium > sect. Epilobium
Sibling taxa
E. anagallidifolium, E. arcticum, E. brachycarpum, E. campestre, E. canum, E. ciliatum, E. clavatum, E. cleistogamum, E. coloratum, E. davuricum, E. densiflorum, E. densum, E. foliosum, E. glaberrimum, E. hallianum, E. hirsutum, E. hornemannii, E. howellii, E. lactiflorum, E. leptocarpum, E. leptophyllum, E. luteum, E. minutum, E. mirabile, E. montanum, E. nevadense, E. nivium, E. obcordatum, E. obscurum, E. oreganum, E. oregonense, E. pallidum, E. palustre, E. parviflorum, E. rigidum, E. septentrionale, E. siskiyouense, E. smithii, E. suffruticosum, E. torreyi
E. anagallidifolium, E. arcticum, E. brachycarpum, E. campestre, E. canum, E. ciliatum, E. cleistogamum, E. coloratum, E. davuricum, E. densiflorum, E. densum, E. foliosum, E. glaberrimum, E. hallianum, E. hirsutum, E. hornemannii, E. howellii, E. lactiflorum, E. leptocarpum, E. leptophyllum, E. luteum, E. minutum, E. mirabile, E. montanum, E. nevadense, E. nivium, E. obcordatum, E. obscurum, E. oreganum, E. oregonense, E. pallidum, E. palustre, E. parviflorum, E. rigidum, E. saximontanum, E. septentrionale, E. siskiyouense, E. smithii, E. suffruticosum, E. torreyi
Synonyms E. adenocaulon subsp. rubescens, E. drummondii, E. drummondii var. latiusculum, E. latiusculum, E. ovatifolium, E. rubescens, E. scalare, E. stramineum E. alpinum var. clavatum
Name authority Haussknecht: Oesterr. Bot. Z. 29: 119. (1879) Trelease: Rep. (Annual) Missouri Bot. Gard. 2: 111, plate 48. (1891)
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