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bog willow-herb, linearleaf willowweed, narrow-leaf willowherb, slender leaf willowherb, épilobe leptophylle

Siskiyou fireweed, Siskiyou rock-fringe, Siskiyou willow-herb

Habit Herbs with threadlike, nearly leafless epigeous stolons terminating in compact, fleshy turions 3–8 × 2–4 mm. Herbs ± suffruticose, shoots from woody caudex with barklike periderm extending to 40 cm below ground, shoots with scaly bases.
Stems

erect, simple to loosely clustered, terete, 15–95 cm, simple to well branched, densely strigillose, often mixed glandular puberulent on inflorescence, rarely with faint strigillose lines decurrent from margins of petioles.

several to many, erect to ascending, loosely clumped, terete, 10–25 cm, rarely branched distal to base, usually short-villous and strigillose throughout, mixed sparsely glandular puberulent distally, rarely subglabrous proximal to inflorescence.

Leaves

opposite proximally, usually alternate, rarely fasciculate distally, subsessile;

blade linear to very narrowly elliptic or sublanceolate, 2–7.5 × 0.1–0.7 cm, usually longer than internodes, base rounded to subcuneate, margins subentire, 4–7 inconspicuous teeth per side, sometimes revolute, lateral veins inconspicuous, apex obtuse proximally to acute distally, both surfaces densely strigillose, increasing distally;

bracts not much reduced.

opposite proximal to inflorescence, alternate and usually crowded distally, sessile;

blade gray-green, narrowly to broadly ovate, 1.3–2.6 × 0.8–2 cm, base rounded to subcordate, margins usually serrulate, 6–12 teeth per side, rarely subentire, veins inconspicuous, 3–5 per side, apex rounded proximally to acute distally, surfaces sparsely short-villous to subglabrous and glaucous;

bracts much reduced.

Inflorescences

erect racemes, densely strigillose, often mixed sparsely glandular puberulent.

erect, compact racemes, densely canescent and glandular puberulent, or subglabrous, only ovaries pubescent.

Flowers

erect;

buds 3–5 × 1.5–2.5 mm;

pedicel 5–12 mm;

floral tube 0.8–1.5 × 1.2–1.8 mm, ring of spreading hairs at mouth inside;

sepals 2.5–4.5 × 0.9–1.3 mm, abaxial surface strigillose;

petals obcordate, white to light pink, 3.5–7 × 1.6–4 mm, apical notch 1–1.8 mm;

filaments white or cream, those of longer stamens 0.8–3.5 mm, those of shorter ones 0.6–2.5 mm;

anthers cream, 0.5–0.9 × 0.4–0.6 mm;

ovary 12–18 mm, densely strigillose, sometimes mixed glandular puberulent;

style cream, 2–3.8 mm, stigma narrowly clavate, entire, 1–1.8 × 0.5–1.2 mm, usually surrounded by, rarely exserted beyond, anthers.

erect;

buds often purplish green, 9–11 × 3.5–5 mm, blunt;

pedicel 6–12 mm;

floral tube 2.1–4 × 2.9–5 mm, prominent ring of tissue 0.3–0.6 mm wide, edged by spreading hairs, 0.9–1.8 mm from base of tube inside;

sepals purplish green, 5–10.5 × 2–3.5 mm, apex acute;

petals pink to rose-purple, obcordate, 10–22.5 × 9.5–15.5 mm, apical notch 2–6.5 mm;

filaments cream, those of longer stamens 6.5–14 mm, those of shorter ones 3.5–11 mm;

anthers cream 1.9–3.3 × 0.7–1.2 mm;

ovary 12–22 mm, ± densely canescent and glandular puberulent;

style white to light pink, 10.5–18 mm, sparsely villous just proximal to stigma, stigma broadly 4-lobed, 1–1.8 × 2.4–4.2 mm, exserted beyond anthers.

Capsules

straight, narrowly cylindrical, 35–80 mm, surfaces densely strigillose;

pedicel 10–35 mm.

25–45 mm, surfaces canescent and glandular puberulent;

pedicel 6–25 mm.

Seeds

narrowly fusiform to narrowly obovoid, 1.5–2.2 ×0.5–0.7 mm, chalazal collar 0.1–0.2 mm, ± pronounced, surface papillose;

coma persistent, dingy white, 6–8 mm.

narrowly obovoid, 1.4–1.9 × 0.6–0.7 mm, with low, obscure chalazal collar, light brown, surface papillose;

coma easily detached, somewhat tawny, 4–8 mm.

2n

= 36.

= 36.

Epilobium leptophyllum

Epilobium siskiyouense

Phenology Flowering Jun–Sep. Flowering Jul–Aug.
Habitat Marshy ground, bogs, fens, low thickets, seepage areas, damp pastures. Stream banks, moist, rocky slopes, montane ridges, sometimes on serpentine areas.
Elevation 0–1000(–2900) m. (0–3300(–9500) ft.) 1600–2500 m. (5200–8200 ft.)
Distribution
from FNA
AK; CA; CO; CT; IA; ID; IL; IN; KS; KY; MA; MD; ME; MI; MN; MO; MT; NC; ND; NE; NH; NJ; NM; NV; NY; OH; OK; OR; PA; RI; SD; TN; TX; UT; VA; VT; WA; WI; WV; WY; AB; BC; MB; NB; NF; NS; NT; ON; PE; QC; SK; SPM
[WildflowerSearch map]
[BONAP county map]
from FNA
CA; OR
[WildflowerSearch map]
[BONAP county map]
Discussion

The range of Epilobium leptophyllum overlaps with that of the related E. palustre, but the former is less common to the north and more common south into the midwestern United States, and absent only from most of the southern tier of states. It is also relatively uncommon in the western United States and Canada. Judging by the number of herbarium sheets that also include E. palustre, E. densum, and even E. coloratum, it sometimes occurs in sympatry with those species and may rarely hybridize with them, based on plants with intermediate morphology and/or sterile fruits.

Fernald described Epilobium nesophilum from the Magdalen Islands (Quebec), and especially Newfoundland, first as a variety of E. densum (1918), then as a separate species (1925).

Epilobium rosmarinifolium Pursh 1813, an illegitimate name (not Haenke 1788), pertains here.

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

Epilobium siskiyouense is endemic to the Klamath region in southwestern Oregon (Jackson County) and north-central California in the Salmon, Scott Bar, and Siskiyou mountains of Siskiyou and Trinity counties. As noted by Hoch and Raven, this geographical range and several morphological features appear to be intermediate between those of E. obcordatum and E. rigidum. All three species have unusually large flowers (12–26 mm) with four-lobed stigmas, and as a group are quite distinct from their congeners in the region. Despite these similarities, the three taxa differ substantially in details of floral structure, especially regarding the dimensions of the floral tube. Specifically, E. rigidum has mean petal length 18.2 mm, floral tubes 1–1.6 × 2.5–3.6 mm; E. siskiyouense mean petal length 17.1 mm, floral tubes 2.1–4 × 2.9–5 mm; and E. obcordatum mean petal length 18.6 mm, floral tubes 3.2–5.2 × 2.2–3.6 mm. Thus, in flowers that are similar in overall size and aspect, E. rigidum has a very short, broad floral tube, E. obcordatum has a relatively long, narrow tube, and E. siskiyouense has a tube intermediate in size and shape. In terms of the ratio of tube length to width, the three taxa do not overlap. Although these characters are difficult to include in a key (since they require floral dissection and/or precise measurements), they are diagnostic for these species.

Epilobium siskiyouense has an additional diagnostic floral character that is unique in the genus. Whereas most other species of Epilobium have a simple ring of spreading hairs, sometimes with a low ridge of tissue near the mouth of the floral tube, E. siskiyouense has a relatively broad ring of tissue (0.3–0.6 mm wide), shaped like a washer, from which spreading hairs arise; this feature may provide protection for the nectar.

Epilobium siskiyouense has two distinct patterns of vestiture on the stems. In some specimens, the lower stems are mixed canescent and glandular puberulent and the inflorescence only glandular puberulent. In other specimens, the stems are subglabrous below a sparsely canescent and glandular puberulent inflorescence. There is no obvious correlation of this difference with any other morphological, ecological, or geographical factors.

(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. 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
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. saximontanum, E. septentrionale, E. smithii, E. suffruticosum, E. torreyi
Synonyms E. densum var. nesophilum, E. nesophilum, E. oliganthum var. gracile, E. palustre var. gracile, E. squamatum, E. tenellum E. obcordatum subsp. siskiyouense, E. obcordatum var. laxum
Name authority Rafinesque: Précis Découv. Somiol., 41. (1814) (Munz) Hoch & P. H. Raven: Madroño 27: 146. (1980)
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