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

cleistogamous boisduvalia, selfing willowherb

Habit Herbs usually with sessile, fleshy, underground turions, or sometimes thick, elongated shoots with dark, decussate scales. Herbs from slender taproot.
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.

terete, 1.5–32 cm, simple or often with sprawling, stout, prostrate proximal branches, proximally glabrous, often distally spreading-hairy and ± glandular puberulent.

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.

subsessile, blade grayish green, linear to narrowly elliptic, proximally broader and surfaces subglabrous, distally narrower and surfaces densely villous, especially on margins and midrib, often folded along midrib, usually early-withering, 1.5–5.5 × 0.2–0.6 cm, base cuneate, margins serrulate, 5–18 low teeth per side, lateral veins obscure, 1–4 per side, apex acute;

bracts scarcely reduced.

Inflorescences

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

erect spikes, leafy, densely villous and glandular puberulent, first flowers at most proximal nodes.

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.

± cleistogamous, suberect, often hidden by subtending bracts;

buds 2–4 × 1–1.5 mm, apiculate;

floral tube 0.5–1 × 0.4–1 mm, raised ring of lax hairs near mouth inside;

sepals pale green or reddish green, not keeled, 1.5–3 × 0.6–1.2 mm, apex acute, abaxial surface villous and glandular puberulent;

petals white to pale pink, 2–5.8 × 0.8–1.8 mm, apical notch 0.5–1.5 mm;

filaments light pink, those of longer stamens 0.6–1.6 mm, those of shorter ones 0.5–0.8 mm;

anthers light yellow, 0.4–0.5 × 0.3–0.5 mm;

ovary 8–11 mm, densely villous and glandular puberulent;

style light pink, 1.4–2.4 mm, stigma capitate, ± 4-lobed to subentire, 0.5–0.9 × 0.4–0.8 mm, surrounded by longer anthers.

Capsules

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

narrowly cylindrical, often curved-ascending, sharply 4-angled with 4 strong ribs, 8–12 mm, beak 1.5–3 mm, tardily dehiscent on distal 1/3, central axis disintegrating, sparsely villous and glandular puberulent;

sessile.

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.

10–14 per tightly packed row, irregularly angular to fusiform, 1.2–1.5 ×0.4–0.6 mm, chalazal collar absent, surface irregularly reticulate.

2n

= 36.

= 30.

Epilobium saximontanum

Epilobium cleistogamum

Phenology Flowering Jul–Sep. Flowering May–Jul.
Habitat Montane semi-shaded stream banks, damp meadows, mossy seeps, wet slatey cliffs, disturbed or seasonally damp areas. Primarily around vernal pools, clay flats, other seasonally moist habitats, usually in heavy clay soil.
Elevation 0–3700 m. (0–12100 ft.) 20–300(–1600) m. (100–1000(–5200) 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
CA
[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 cleistogamum is an annual species endemic to heavy clay soil in the Central Valley of California and surrounding foothills, from southern Tehama County to northern Tulare County and into the Sacramento River delta in Contra Costa and Solano counties, and barely to San Luis Obispo County in the southern Coast Range. Flowering often commences at the first or second proximal node, and flowers are frequently cleistogamous. The seeds are arranged nearly horizontally and are irregularly angular due to tight packing in the rigid capsules. Plants characteristically have decumbent branches and tardily dehiscent capsules that shed their seeds only following rains, often many months after fruits matured and plants were green (P. H. Raven 1969).

(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. Epilobiopsis
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. 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 Boisduvalia cleistogama, Oenothera cleistogama
Name authority Haussknecht: Oesterr. Bot. Z. 29: 119. (1879) (Curran) Hoch & P. H. Raven: Phytologia 73: 458. (1993)
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