Epilobium siskiyouense
Epilobium obscurum
Siskiyou fireweed, Siskiyou rock-fringe, Siskiyou willow-herb
dwarf willowherb, obscure willow-herb
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.
erect or ascending, subterete, 20–80 cm, often well branched from base, sometimes also distally, subglabrous proximal to inflorescence with raised strigillose lines decurrent from margins of petioles, strigillose distally.
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.
opposite proximal to inflorescence, alternate distally, petiole 0–2 mm;
blade green or slightly bluish green, lanceolate to narrowly ovate, 1.5–10 × 0.4–1.8 cm, ± shorter than internodes, base rounded to attenuate, margins denticulate with 15–40 evenly spaced teeth per side, veins prominent, 3–7 per side, apex subacute, surfaces sparsely strigillose, mainly on margins and veins;
bracts gradually reduced.
erect, compact racemes, densely canescent and glandular puberulent, or subglabrous, only ovaries pubescent.
erect racemes or sparse panicles, strigillose.
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.
erect;
buds 2–5 × 1–2.5 mm;
pedicel 2–14 mm;
floral tube 0.8–1 × 1.1–1.5 mm, conspicuous ring of spreading hairs at mouth inside, mixed strigillose and sparse glandular puberulent externally;
sepals lanceolate, somewhat keeled, 2.5–4 × 1–1.3 mm, abaxial surface strigillose;
petals rose-purple, 3.5–6 × 1.8–3 mm, apical notch 0.8–1.4 mm;
filaments pale pink, those of longer stamens 2–2.2 mm, those of shorter ones 0.8–1.3 mm;
anthers yellow, 0.7–0.8 × 0.4–0.5 mm;
ovary 12–38 mm, strigillose;
style white, 2.5–3.5 mm, glabrous, stigma clavate, 1.5–2 × 0.6–0.8 mm, surrounded by longer anthers.
25–45 mm, surfaces canescent and glandular puberulent;
pedicel 6–25 mm.
40–70 mm, surfaces strigillose;
pedicel 4–16 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.
narrowly obovoid, 0.9–1 × 0.3–0.4 mm, chalazal collar inconspicuous, brown, surface coarsely papillose;
coma readily detached, dull white, 4–5 mm.
= 36.
= 36.
Epilobium siskiyouense
Epilobium obscurum
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.)
Epilobium obscurum, native throughout Europe and the European part of Russia except the far north, to Turkey and the Azores, is one of several Eurasian species that has naturalized in North America, following multiple early introductions around east coast port cities, and later around the Great Lakes. E. G. Voss(1972–1996, vol. 2) reported a collection of E. obscurum made in 1927 in Michigan near Detroit, but despite efforts by Voss and others, no additional collections of this species have been detected in that area, suggesting that it failed to become naturalized there.
In the Pacific Northwest, W. Suksdorf grew and collected at least six European taxa in his garden in Bingen (Klickitat County, Washington); this included E. obscurum (as early as 1922) but none of those taxa became naturalized. However, one or more independent new introductions in the Seattle (P. Zika, pers. comm.) and Vancouver (F. Lomer, pers. comm.) regions appear to be more persistent and the species should be considered naturalized there.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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