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

marsh willow-herb, marsh willowweed, swamp willowherb, épilobe palustre

Habit Herbs usually with sessile, fleshy, underground turions, or sometimes thick, elongated shoots with dark, decussate scales. Herbs with multiple filiform epigeous stolons with widely spaced, small leaves, terminating in condensed, dark, small turions 3–7 × 2–3 mm.
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.

erect, loosely clustered, terete, 5–80 cm, simple to well branched, subglabrous on proximal internodes, sometimes with faint strigillose lines decurrent from margins of petioles, densely strigillose 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.

opposite proximal to inflorescence, alternate distally, subsessile;

blade lanceolate or narrowly elliptic to sublinear, 1.5–7 × 0.2–1.9 cm, base cuneate, margins entire or inconspicuously denticulate, 2–6 teeth per side, veins inconspicuous, apex acute or acuminate, surfaces strigillose abaxially, subglabrous adaxially or strigillose only on margins and veins;

bracts smaller and narrower.

Inflorescences

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

nodding in bud, later erect, racemes, not branched, densely strigillose, rarely mixed sparsely glandular puberulent.

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 to spreading;

buds 2–5 × 1.5–2.5 mm;

pedicel 8–12 mm;

floral tube 0.6–1.8 × 1.3–2.2 mm, ring of spreading hairs at mouth inside;

sepals 1.4–4.5 × 0.8–1.5 mm, abaxial surface strigillose;

petals usually white, rarely pink, 2–9 × 1.8–5 mm, obcordate, apical notch 0.6–1.6 mm;

filaments cream or white, those of longer stamens 0.8–3.5 mm, those of shorter ones 0.4–2.1 mm;

anthers 0.4–1 × 0.3–0.7 mm;

ovary 12–35 mm, strigillose;

style cream, 1.5–4.5 mm, stigma clavate to cylindrical, entire, 0.8–2 × 0.5–1.4 mm, usually surrounded by, rarely exserted beyond, anthers.

Capsules

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

straight or upcurved, 25–90 mm, surfaces strigillose;

pedicel 15–35(–60) 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.

elliptic, attenuate to narrowly fusiform, 1.4–2.2 × 0.4–0.5 mm, chalazal collar 0.1–0.25 mm, conspicuous, surface finely papillose;

coma persistent, white, 5–7 mm.

2n

= 36.

= 36.

Epilobium saximontanum

Epilobium palustre

Phenology Flowering Jul–Sep. Flowering Jul–Sep.
Habitat Montane semi-shaded stream banks, damp meadows, mossy seeps, wet slatey cliffs, disturbed or seasonally damp areas. Low, boggy areas, swamps, saturated stream banks, mossy meadows.
Elevation 0–3700 m. (0–12100 ft.) 0–1000(–2600) m. (0–3300(–8500) 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; CT; MA; ME; MI; MN; MT; NH; NJ; NY; OR; PA; RI; SD; UT; VT; WI; WY; AB; BC; MB; NB; NL; NS; NT; NU; ON; PE; QC; SK; YT; SPM; Greenland; n Eurasia; c Eurasia
[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 palustre is an extremely widespread circumboreal species that is relatively common from Alaska across Canada, especially around the Great Lakes to the Maritime provinces (mostly below 1000 m). This species is somewhat less common in the northeastern United States, and only scattered in the mountains of the western United States, south to California and Colorado (to 3000 m). It also occurs in ice-free regions of Greenland south of 70º north latitude, in northern and central Europe, across most of subarctic Russia to the Caucasus, the Himalaya complex, and eastern Asia, including Japan and the Russian Far East.

Epilobium palustre shows considerable variation across its very wide distribution and, not surprisingly, distinctive local races, which sometimes have been named formally, including several from northeastern North America. Within series Palustriformes by C. Haussknecht (1884), M. L. Fernald (1944d) clarified much confusion in names at that time, clearly delineating and establishing the nomenclature of E. davuricum, E. leptophyllum, E. palustre, and E. densum. Fernald also recognized E. nesophilum (see discussion under 18. E. leptophyllum) and E. pylaieanum, the latter based on small plants of E. palustre from southern Newfoundland.

Epilobium lineare Muhlenberg and E. palustre var. albiflorum Lehmann are illegitimate names that pertain here.

(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. 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. 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 Chamaenerion palustre, E. molle var. sabulonense, E. nesophilum var. lupulinum, E. nesophilum var. sabulonense, E. oliganthum, E. palustre var. albescens, E. palustre var. grammadophyllum, E. palustre var. lapponicum, E. palustre var. longirameum, E. palustre var. oliganthum, E. palustre var. sabulonense, E. pylaieanum, E. wyomingense
Name authority Haussknecht: Oesterr. Bot. Z. 29: 119. (1879) Linnaeus: Sp. Pl. 1: 348. (1753)
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