Epilobium leptophyllum
Onagraceae tribe Epilobieae
bog willow-herb, linearleaf willowweed, narrow-leaf willowherb, slender leaf willowherb, épilobe leptophylle
erect, simple to loosely clustered, terete, 15–95 cm, simple to well branched, densely strigillose, often mixed glandular puberulent on inflorescence, rarely with faint strigillose lines decurrent from margins of petioles.
opposite proximally, usually alternate, rarely fasciculate distally, subsessile;
blade linear to very narrowly elliptic or sublanceolate, 2–7.5 × 0.1–0.7 cm, usually longer than internodes, base rounded to subcuneate, margins subentire, 4–7 inconspicuous teeth per side, sometimes revolute, lateral veins inconspicuous, apex obtuse proximally to acute distally, both surfaces densely strigillose, increasing distally;
bracts not much reduced.
opposite at least near base or throughout, alternate distally, or sometimes alternate throughout;
stipules absent.
erect racemes, densely strigillose, often mixed sparsely glandular puberulent.
erect;
buds 3–5 × 1.5–2.5 mm;
pedicel 5–12 mm;
floral tube 0.8–1.5 × 1.2–1.8 mm, ring of spreading hairs at mouth inside;
sepals 2.5–4.5 × 0.9–1.3 mm, abaxial surface strigillose;
petals obcordate, white to light pink, 3.5–7 × 1.6–4 mm, apical notch 1–1.8 mm;
filaments white or cream, those of longer stamens 0.8–3.5 mm, those of shorter ones 0.6–2.5 mm;
anthers cream, 0.5–0.9 × 0.4–0.6 mm;
ovary 12–18 mm, densely strigillose, sometimes mixed glandular puberulent;
style cream, 2–3.8 mm, stigma narrowly clavate, entire, 1–1.8 × 0.5–1.2 mm, usually surrounded by, rarely exserted beyond, anthers.
actinomorphic or slightly zygomorphic, 4-merous;
sepals erect or spreading;
stamens 2 times as many as sepals;
pollen shed in tetrads or monads.
a slender, cylindrical, loculicidal capsule.
straight, narrowly cylindrical, 35–80 mm, surfaces densely strigillose;
pedicel 10–35 mm.
narrowly fusiform to narrowly obovoid, 1.5–2.2 ×0.5–0.7 mm, chalazal collar 0.1–0.2 mm, ± pronounced, surface papillose;
coma persistent, dingy white, 6–8 mm.
(1 or) many per locule, with tuft of hairs (coma) at chalazal end, sometimes without coma.
= 36.
Epilobium leptophyllum
Onagraceae tribe Epilobieae
The range of Epilobium leptophyllum overlaps with that of the related E. palustre, but the former is less common to the north and more common south into the midwestern United States, and absent only from most of the southern tier of states. It is also relatively uncommon in the western United States and Canada. Judging by the number of herbarium sheets that also include E. palustre, E. densum, and even E. coloratum, it sometimes occurs in sympatry with those species and may rarely hybridize with them, based on plants with intermediate morphology and/or sterile fruits.
Fernald described Epilobium nesophilum from the Magdalen Islands (Quebec), and especially Newfoundland, first as a variety of E. densum (1918), then as a separate species (1925).
Epilobium rosmarinifolium Pursh 1813, an illegitimate name (not Haenke 1788), pertains here.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Genera 2, species 173 (2 genera, 43 species in the flora).
Epilobium and its close relatives have been recognized historically either as part of Onagreae (A. P. de Candolle 1828b), sometimes as a subtribe (É. Spach 1834–1848, vol. 4; J. Torrey and A. Gray 1838–1843, vol. 1), or as the distinct Epilobieae (R. Raimann 1893; P. A. Munz 1965; P. H. Raven 1976). The synapomorphies for Epilobieae as currently delimited include its highly condensed, heteropycnotic chromosomes with a base chromosome number of x = 18, sepals held erect or spreading (not reflexed) throughout anthesis, and the presence of a coma of hairs on the seeds (secondarily lost in some species). Molecular support for the tribe is strong (97–100% BOOTSTRAP support; D. A. Baum et al. 1994; R. A. Levin et al. 2004).
Endlicher established Epilobieae and included Oenothera within it; it is unclear how or whether his concept differed from Onagreae of A. P. de Candolle (1828b). É. Spach (1834–1848, vol. 4) recognized these genera as Onagreae and differentiated so-called sect. Oenotherinae from sect. Epilobieae, placing in the latter not only Epilobium and related groups, but also Clarkia and its segregates. J. Torrey and A. Gray (1840) excluded Clarkia from their Epilobiinae and also excluded Boisduvalia, a delimitation also followed by R. Raimann (1893) for his Epilobieae. Epilobieae did not assume its current delimitation, including only Epilobium and its close relatives, until the works of P. A. Munz (1941) and P. H. Raven (1964).
G. L. Stebbins (1971) and P. H. Raven (1976) considered the diverse chromosome numbers in Epilobieae and proposed that the species of Boisduvalia (now a section of Epilobium) with n = 9 or 10 represented the original base chromosome number for the tribe, and that these numbers were derived from x = 11 which is found in Circaeeae, Gongylocarpeae, and Lopezieae (W. L. Wagner et al. 2007). They proposed a series of aneuploid reductions from n = 9 or 10 to n = 6, followed by polyploidy to produce the array of numbers in Epilobium (n = 12, 13, 15, 16, 18, 30) and Boisduvalia (n = 9, 10, 15, 19). D. A. Baum et al. (1994) demonstrated that molecular data did not support that hypothesis and found that a monophyletic Chamaenerion (n = 18, 36, 54) forms a strongly distinct sister branch to Epilobium, within which sect. Epilobium (n = 18) is monophyletic and sister to the rest of Epilobium, including the former segregates Boisduvalia and Zauschneria. The data from Baum et al. suggested that Epilobieae are primitively polyploid, with numbers based on x = 18, which is unique in the family. Using comparable sampling and some additional genes, R. A. Levin et al. (2004) found strong support for the phylogeny proposed by Baum et al.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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