Epilobium siskiyouense
Epilobium nevadense
Siskiyou fireweed, Siskiyou rock-fringe, Siskiyou willow-herb
Nevada willowherb
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, terete, 10–50 cm, branched at base and apically, densely strigillose throughout, sometimes mixed villous 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.
proximal pairs often early-deciduous, petiole 1–4 mm, blade lanceolate-elliptic to narrowly so, ± folded along midrib, 0.9–1.7 × 0.2–0.6 cm, shorter than internodes, base attenuate or narrowly cuneate, margins denticulate, 6–10 low teeth per side, lateral veins inconspicuous or absent, apex acute with deciduous, rigid mucronate gland, surfaces usually glabrescent with scattered hairs on abaxial midrib, rarely strigillose-villous throughout;
bracts much reduced, sublinear, often attached to pedicel.
erect, compact racemes, densely canescent and glandular puberulent, or subglabrous, only ovaries pubescent.
erect, open racemes or panicles, strigillose, often mixed glandular puberulent.
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 to ± nodding;
buds rounded-obovoid, 5–6 × 3–4 mm;
floral tube with slight constriction 2–3 mm distal to base, 2.7–3.2(–5) × 1.8–2.5(–3.1) mm, without ring or scales inside, glabrous;
sepals erect or sometimes deflexed in late anthesis, green or reddish green, lanceolate, 2.6–4.2 × 0.9–1.3 mm, apex acute;
petals deep rose-purple, obcordate, 5–7.2 × 3.2–4.1 mm, apical notch 2–3 mm;
filaments cream or white, those of longer stamens 5–7.5 mm, those of shorter ones 3.5–5.5 mm;
anthers cream, 1–1.8 × 0.5–0.8 mm, scarcely apiculate;
ovary 2.5–3.8 mm, densely strigillose and/or glandular puberulent;
style cream, 6–9.5 mm, glabrous, stigma 4-lobed, 0.8–1.2 × 1–1.5 mm, lobes reflexed or sometimes incompletely spread, then forming cup-like structure, exserted beyond longer anthers.
25–45 mm, surfaces canescent and glandular puberulent;
pedicel 6–25 mm.
erect, subfusiform, 8–12 mm, surfaces strigillose and/or glandular puberulent;
pedicel 1–1.8 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.
obovoid, with constriction 0.6–1 mm from micropylar end, 2.1–2.9 × 1.2–1.5 mm, very inconspicuous chalazal collar 0.05–0.06 mm wide, dark brown, surface low papillose, papillae often with central pit;
coma easily detached, white, 6–7.5 mm.
= 36.
= 30.
Epilobium siskiyouense
Epilobium nevadense
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.)
In his description of Epilobium nevadense, Munz clearly recognized its affinity to E. nivium and suggested a close relationship between these two species and E. brachycarpum, based on similarities in seed and floral morphology. S. R. Seavey and P. H. Raven (1977c) demonstrated the close affinity between E. nivium and E. nevadense by forming fully fertile (99%) hybrids. However, compared to E. nivium, E. nevadense has denticulate, subglabrous leaves (versus subentire, densely pubescent leaves) and shorter floral tube [2.7–3.2(–5) mm] versus longer (5.2–9.5 mm) in E. nivium; furthermore, the two have completely non-overlapping geographical ranges. In overall morphology and cytology, these two species (and the somewhat more distantly related E. suffruticosum) are quite distinct from the rest of the genus.
Originally known only from the Charleston Mountains in southern Nevada, Epilobium nevadense has since been collected in northern Arizona, Eureka and Lincoln counties in Nevada, and in three counties of southwestern Utah. It may be more widespread in this region, much of which (especially in southern Nevada) consists of military reserves that are inaccessible to collectors. Although it was at one time considered endangered (S. D. Ripley 1975) due to the relatively low number of collections and threats from increased recreational use in its area of occurrence, it is no longer considered a candidate for listing (http://endangered.fws.gov). Several collections of this species show evidence of seed predation, apparently by moth larvae (H. N. Mozingo and Margaret Williams 1980), and S. R. Seavey and P. H. Raven (1977c) reported that larvae found in capsules from the locality in the Charleston Mountains were identified as Mompha (Momphidae, Gelechioidea).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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