Epilobium siskiyouense
Epilobium parviflorum
Siskiyou fireweed, Siskiyou rock-fringe, Siskiyou willow-herb
hoary willowherb, small-flower hairy willow-herb, small-flower willow-herb, smaller hairy 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, terete, 18–100(–160) cm, well branched distally, densely gray-villous proximally, mixed villous and glandular puberulent distally, often with raised strigillose lines decurrent from margins of petioles.
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, petioles 1–3 mm proximally, sessile distally;
blade narrowly lanceolate or oblong-lanceolate, 3–12 × 0.5–2.5 cm, often exceeding internodes, base rounded to broadly cuneate, margins serrulate, with 15–60 teeth per side, veins 4–8 per side, apex subacute, surfaces ± densely villous, hairs sometimes appressed;
bracts usually much reduced.
erect, compact racemes, densely canescent and glandular puberulent, or subglabrous, only ovaries pubescent.
erect racemes or often leafy panicles.
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 3.5–5.5 × 1.8–3 mm;
pedicel 3–10 mm;
floral tube 1–1.9 × 1.3–2.5 mm, a ring of spreading hairs at mouth within, densely villous and glandular puberulent abaxially;
sepals narrowly lanceolate, often keeled, 2.5–6 × 1–1.5 mm;
petals usually pink to rose-purple, rarely white, broadly obovate, 4–8.5 × 3–4.5 mm, apical notch 1–4 mm;
filaments cream to light purple, those of longer stamens 2–6 mm, those of shorter ones 1–3.5 mm;
anthers oblong, 0.8–1.3 × 0.4–0.6 mm;
ovary 10–30 mm, mixed villous and glandular puberulent;
style white to pink, 2.2–6 mm, glabrous, stigma deeply 4-lobed, 1–1.5 × 2.2–4 mm, lobes 1–1.8 mm, initially erect, later recurved, surrounded by or barely exserted beyond anthers.
25–45 mm, surfaces canescent and glandular puberulent;
pedicel 6–25 mm.
30–70 mm, surfaces usually glandular puberulent, often mixed villous, rarely glabrescent;
pedicel 5–18 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, 0.8–1.1 × 0.4–0.5 mm, chalazal collar inconspicuous, brown, surface coarsely papillose;
coma easily detached, dingy white, 5–9 mm.
= 36.
= 36.
Epilobium siskiyouense
Epilobium parviflorum
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 parviflorum is widespread in Eurasia, from Europe through the Caucasus and southern Asia to eastern China (Chen C. J. et al. 1992), and in northwestern Africa and the Canary Islands (P. H. Raven 1967). Prior to the report of naturalized populations of E. parviflorum in Ontario by N. J. Purcell (1976), the species was considered an ephemeral adventive in New Jersey, New York, and Pennsylvania, where collections were made on ballast heaps in 1877–1880 (W. Trelease 1891; H. A. Gleason 1952, vol. 2) but not subsequently. However, recent collections indicate well-established populations scattered widely across the Great Lakes region (Purcell; E. G. Voss 1972–1996, vol. 2; T. S. Cooperrider and B. K. Andreas 1991) and more recently in the Pacific Northwest. Epilobium parviflorum is clearly naturalized and can be expected to spread farther, given its weedy nature (Raven and T. E. Raven 1976).
Epilobium parviflorum most closely resembles E. hirsutum, sharing the otherwise unique combination of densely villous pubescence and 4-lobed stigmas, but differs by having smaller flowers, leaves not clasping and/or decurrent on stems, and perennating by rosettes rather than by thick ropy stolons. The two species co-occur throughout most of their range in Eurasia, and although their adventive ranges in North America are quite similar, E. hirsutum has spread much more widely and rapidly.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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