Epilobium siskiyouense
Epilobium arcticum
Siskiyou fireweed, Siskiyou rock-fringe, Siskiyou willow-herb
arctic willowherb, épilobe arctique
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.
single or many, suberect or nodding in bud, often clumped, terete, (2–)5–18 cm, rarely branched, 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 proximally, alternate on inflorescence, subsessile;
blade obovate to narrowly elliptic to distally sublinear, 0.8–2.1 × 0.2–0.5 cm, base cuneate to attenuate, margins subentire to minutely denticulate, 2–5 low teeth per side, veins inconspicuous, apex obtuse to truncate, surfaces glabrous or sparsely strigillose on abaxial midrib;
bracts reduced and narrower.
erect, compact racemes, densely canescent and glandular puberulent, or subglabrous, only ovaries pubescent.
often nodding in bud, erect later, few-flowered racemes, subglabrous or sparsely 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.
nodding to suberect;
buds 2–5 × 1–2.5 mm;
pedicel 6–12(–18) mm, exceeding subtending bracts;
floral tube 0.5–1.1 × 0.6–1.3 mm, with or without sparse ring of hairs at mouth inside;
sepals green or flushed purple, 1.1–1.8 × 0.6–1.2 mm;
petals white, sometimes flushed pink, 2.2–4.5 × 1.4–2.5 mm, apical notch 0.5–0.7 mm;
filaments white or light pink, those of longer stamens 4–5 mm, those of shorter ones 2–3 mm;
anthers cream, 0.3–0.4 × 0.2–0.3 mm;
ovary 8–18 mm, subglabrous to strigillose;
style white, 2.5–3.5mm, stigma clavate, 1–1.8 × 0.5–1 mm, surrounded by anthers.
25–45 mm, surfaces canescent and glandular puberulent;
pedicel 6–25 mm.
erect, often reddish purple, 20–42 mm, surfaces sparsely strigillose;
pedicel 25–40 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 fusiform to narrowly obovoid, 1.1–1.7 × 0.3–0.5 mm, with distinct chalazal collar 0.1–0.2 mm, light brown, surface rugose or reticulate;
coma persistent, dull white, 5–7 mm.
= 36.
= 36.
Epilobium siskiyouense
Epilobium arcticum
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 arcticum has the most northern distribution in the genus, occurring almost exclusively above the Arctic Circle (about 66ºN) in Alaska, Canada, coastal Greenland north of 69ºN, and the Russian Federation, although it apparently is absent from northern Europe (P. H. Raven 1968).
Epilobium arcticum has often been combined or confused with E. davuricum, but they differ in size, leaf shape and size, and seed size, as well as in distribution (S. G. Aiken et al., http://nature.ca/aaflora/data). Most populations of E. arcticum occur at (62–)67–80ºN, in the Tundra zone, often on the islands of the Arctic Archipelago (especially Axel Heiberg, Baffin, and Ellesmere islands). Most populations of E. davuricum, on the other hand, occur south of the Arctic Circle in the Boreal and Taiga zones, and rarely, if ever, on those islands.
Because Epilobium arcticum grows at latitudes with extremely short growing seasons, plants often commence flowering at the second or third most-proximal node.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
CA
OR
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