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

glandular willowherb, Hall's willowherb, Sierra willowherb

Habit Herbs usually with sessile, fleshy, underground turions, or sometimes thick, elongated shoots with dark, decussate scales. Herbs with small, 3–6 mm, round or oblong, compact turions 1–5 cm below ground.
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.

strict, erect, terete, 2–50(–60) cm, rarely branched only in larger plants, subglabrous proximal to inflorescence except for raised strigillose lines decurrent from margins of petioles, or sometimes ± densely long-villous throughout with inconspicuous decurrent lines.

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 proximally, alternate on inflorescence, subsessile or proximally with petioles 1–1.5 mm;

blade ovate proximally to lanceolate or narrowly elliptic distally, 0.5–4.7 × 0.2–1.4 cm, base rounded to cuneate, margins subentire proximally to denticulate distally, 8–20 teeth per side, veins inconspicuous, 3–6 per side, apex obtuse to subacute, surfaces mostly glabrous with strigillose margins;

bracts much reduced.

Inflorescences

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

usually nodding in bud, erect later, open racemes, sometimes congested, usually mixed strigillose and glandular puberulent, rarely also mixed villous, or rarely subglabrous.

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 2–5 × 1–2 mm;

pedicel 3–8 mm;

floral tube 0.5–1.7 × 0.8–1.6 mm, with slightly raised ring of spreading hairs at mouth inside;

sepals green, 1.2–2.8 × 0.5–1 mm, abaxial surface subglabrous or sparsely glandular puberulent;

petals white, often fading pink, 1.6–5.5 × 1.2–3 mm, apical notch 0.3–1.2 mm;

filaments white or cream, those of longer stamens 0.6–2.5 mm, those of shorter ones 0.4–1.5 mm;

anthers cream, 0.2–0.9 × 0.2–0.5 mm;

ovary 10–14 mm, strigillose and glandular puberulent or subglabrous;

style cream, 0.8–5 mm, stigma clavate, entire, 0.4–1.2 × 0.3–0.7 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.

very narrowly cylindrical, (15–)24–60 mm, surfaces usually subglabrous to mixed strigillose and glandular puberulent, rarely sparsely villous;

pedicel 8–40 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 fusiform to narrowly obovoid, 1.1–1.6 × 0.4–0.6 mm, chalazal collar ± conspicuous, 0.05–0.2 mm, light brown, surface papillose;

coma easily detached, white, 3–6 mm.

2n

= 36.

= 36.

Epilobium saximontanum

Epilobium hallianum

Phenology Flowering Jul–Sep. Flowering Jun–Sep.
Habitat Montane semi-shaded stream banks, damp meadows, mossy seeps, wet slatey cliffs, disturbed or seasonally damp areas. Semi-shaded stream banks, wet grassy slopes or meadows, bogs, seasonally wet sites, vernal pools.
Elevation 0–3700 m. (0–12100 ft.) 100–3700 m. (300–12100 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
AZ; CA; CO; ID; MT; NM; NV; OR; SD; UT; WA; WY; AB; BC; SK
[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 hallianum has condensed fleshy turions and generally strict habit, suggesting an affinity with E. ciliatum or E. saximontanum, both with the AA arrangement. However, E. hallianum has the BB arrangement (S. R. Seavey and P. H. Raven 1978) and apparently more distant relationship to those other species.

In different parts of its geographical range Epilobium hallianum shows considerable morphological variability, especially in leaf shape and margins, and in type and pattern of stem vestiture, including plants in the southern part of its range with densely villous stems that have been treated as E. ursinum. In part because of this variability and in part because the very characteristic condensed turions are easily lost during collection and/or often overlooked, E. hallianum is frequently misidentified.

(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. 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. brevistylum var. pringleanum, E. brevistylum var. subfalcatum, E. brevistylum var. tenue, E. brevistylum var. ursinum, E. delicatum var. tenue, E. glandulosum var. tenue, E. pringleanum, E. pringleanum var. tenue, E. ursinum, E. ursinum var. subfalcatum
Name authority Haussknecht: Oesterr. Bot. Z. 29: 119. (1879) Haussknecht: Monogr. Epilobium, 261. (1884) — (as halleanum)
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