Epilobium siskiyouense
Epilobium oreganum
Siskiyou fireweed, Siskiyou rock-fringe, Siskiyou willow-herb
Grant's Pass willowherb, Oregon fireweed, Oregon 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.
several to many, ascending or erect, terete, loosely clumped, 40–100 cm, usually well-branched apically, ± glabrous and glaucous proximal to inflorescence, without distinct raised lines, sparsely mixed strigillose and glandular pubescent proximally.
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 broad, 1–3 mm;
blade narrowly lanceolate to narrowly ovate, 3–9 × 0.7–2.5 cm, base rounded to cuneate, margins finely serrulate, 20–40 teeth per side, veins reddish green, conspicuous, 6–10 per side, apex acute, surfaces glabrous and often glaucous, crowded proximally;
bracts much reduced and narrower.
erect, compact racemes, densely canescent and glandular puberulent, or subglabrous, only ovaries pubescent.
erect racemes or open panicles, often branched, glandular puberulent, sometimes mixed 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 5–8 × 2–3.5 mm, often with stigma exserted;
pedicel 2–4 mm;
floral tube 2–3 × 1.8–3 mm, with ring of spreading hairs near base of tube inside;
sepals often flushed red, 6–10 × 2.1–2.8 mm, abaxial surface mixed strigillose and glandular puberulent;
petals dark pink to rose-purple, (6–)10–15 × 4.5–6 mm, apical notch 2.6–3 mm;
filaments cream or light pink, those of longer stamens 6–8 mm, those of shorter ones 3.5–4.5 mm;
anthers cream or yellow, 1–1.2 × 0.5–0.6 mm;
ovary 20–25 mm, densely glandular puberulent and mixed strigillose;
style cream or yellow, 9–13 mm, stigma broadly and sometimes irregularly 4-lobed, 1–1.5 × 2.1–2.9 mm, exserted beyond anthers.
25–45 mm, surfaces canescent and glandular puberulent;
pedicel 6–25 mm.
25–45 mm, surfaces mixed sparsely glandular puberulent and strigillose, often with reduced fertile seed set;
pedicel 3–6 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, 0.9–1.3 × 0.4–0.5 mm, chalazal collar 0.1–0.15 × 0.2–0.25 mm, gray-brown, surface with conspicuous parallel longitudinal ridges of laterally flattened papillae;
coma readily detached, white, 4–6 mm.
= 36.
= 36.
Epilobium siskiyouense
Epilobium oreganum
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 oreganum is endemic to a small region of southern Oregon (Douglas and Josephine counties, mainly from Grants Pass south along the Illinois River) and northern California (Del Norte, Humboldt, Siskiyou, Tehama, and Trinity counties, especially along the South Fork of the Trinity and Klamath rivers).
Epilobium oreganum is the only other species that shares the distinctive ridged seeds found also in E. ciliatum, and looks quite similar to that species; both also have the AA chromosomal arrangement. However, it differs from E. ciliatum in being generally glabrous and glaucous, and by having exserted 4-lobed stigmas. W. Trelease (1891) and later P. A. Munz (1965) considered E. oreganum to be of hybrid origin, the presumptive parents being E. glaberrimum (glabrous) and so called E. adenocaulon (= E. ciliatum; ridged seeds). Some specimens have notably reduced seed set; whether that is the result of a hybrid origin, a failure to outcross in a plant with a very exserted stigma, or to another cause is not clear. The exact affinities of E. oreganum are uncertain, but it occupies a restricted and distinctive ecogeographical range and has a unique combination of morphological features.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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