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California willowherb, chaparral willowherb, desert willowherb, little willowherb, minute willowherb, small-flower willowherb

Humboldt County fuchsia, northern willowherb

Habit Herbs slender. Herbs usually not suffruticose, with basal shoots from thickened caudex, often decussate scales at base.
Stems

strict, erect, sometimes reddish green, terete, 3.5–40 cm, simple or freely branched, subglabrous proximally to strigillose and glandular puberulent distally.

decumbent, often matted, grayish green, terete, 5–25 cm, well-branched throughout, densely white-canescent proximally, mixed strigillose, villous, and glandular puberulent distally.

Leaves

alternate distally, not fasciculate, petiole 0–2 mm, blade subspatulate proximally to lanceolate, oblanceolate, or narrowly elliptical distally, not folded along midrib, 0.9–2.5 × 0.2–0.6 cm, shorter than internodes, base tapered, margins entire or scarcely denticulate, 1–4 teeth per side, lateral veins obscure, apex subacute or often blunt proximally, surfaces subglabrous or with scattered hairs along margins;

bracts much reduced, sometimes attached to pedicel.

densely spaced, opposite proximal to inflorescence, alternate or fasciculate distally, petiole 0–2 mm, blade grayish green to green, lanceolate or elliptic to narrowly ovate, 1–3.5(–4) × 0.4–1.1 cm, base cuneate or attenuate, margins subentire to low-denticulate, 5–8 teeth per side, veins inconspicuous, 3–5 per side, apex acute, sometimes with caducous dark mucro, surfaces densely white-canescent and eglandular proximally, changing abruptly on inflorescence to glandular puberulent mixed with scattered villous;

bracts somewhat reduced.

Inflorescences

erect racemes or open panicles, relatively loose and uncrowded, branches thin, mixed strigillose and glandular puberulent.

ascending spikes or racemes, densely glandular puberulent.

Flowers

erect or, sometimes, nodding in bud;

buds broadly ovoid, 1.2–2.5 × 1–1.5 mm;

floral tube 1.1–1.5 × 1–1.4 mm, usually with ring of spreading hairs at mouth inside;

sepals 0.5–2.5 × 0.4–1.3 mm, apex acute, abaxial surface strigillose, sometimes mixed glandular puberulent;

petals white to pink, 2–5 × 1.5–3 mm, apical notch 0.2–1.9 mm;

filaments white, those of longer stamens 0.5–3 mm, those of shorter ones 0.3–2 mm;

anthers 0.6–1 × 0.5–0.8 mm;

ovary 4–9 mm, mixed strigillose and glandular puberulent;

style light pink, 1–3.5 mm, stigma subclavate to obscurely 4-lobed, 0.4–0.6 × 0.4–0.5 mm, surrounded by longer anthers.

buds 12–15 × 4–5.5 mm, subsessile or pedicels 1–2 mm;

floral tube same color as petals, 17–23 × 3.5–5 mm, with ring of scales 4–5 mm from base inside;

sepals same color as petals, 7–12 × 2.5–3.5 mm;

petals red-orange, 8–14 × 5–6.5 mm, apical notch 1.8–2.4 mm;

filaments orange or red, those of longer stamens 15–17 mm, those of shorter ones 13–15 mm;

anthers 2.8–3.2 × 0.7–1 mm;

ovary 5–11 mm, glandular puberulent;

style light orange, 40–45 mm, stigma 4-lobed, 0.9–1.1 × 2.2–2.6 mm, exserted 8–10 mm beyond anthers.

Capsules

9–28 mm, surfaces strigillose and glandular puberulent;

pedicel 3–10 mm.

± straight, 20–26 mm, ± beaked, surfaces glandular puberulent;

sessile or pedicel 1–3 mm.

Seeds

obovoid, without constriction, 0.9–1.2 × 0.4–0.6 mm, low chalazal collar 0.1–0.2 mm wide, brown, surface reticulate;

coma easily detached, white, 2.5–3 mm.

broadly to narrowly obovoid, with constriction 0.7–0.8 mm from micropylar end, 1.8–2.4 × 1.1–1.3 mm, chalazal collar inconspicuous, light brown, surface low-papillose;

coma easily detached, dingy white, 6–7 mm.

2n

= 26.

= 30.

Epilobium minutum

Epilobium septentrionale

Phenology Flowering Apr–Sep. Flowering Aug–Sep.
Habitat Open, dry places, along roads, disturbed areas. Rocky ledges and serpentine slopes along rivers.
Elevation 90–1900 m. (300–6200 ft.) 10–1900 m. (0–6200 ft.)
Distribution
from FNA
CA; ID; MT; NV; OR; WA; BC
[WildflowerSearch map]
[BONAP county map]
from FNA
CA
[BONAP county map]
Discussion

Epilobium minutum, like the similar E. foliosum, also occasionally produces cleistogamous flowers, and is modally autogamous in any event. S. R. Seavey et al. (1977b) observed that E. minutum is less common than E. foliosum in the southern part of their overlapping ranges and more common in the north. Several sheets (for example, Lawler 3276, California, Butte Co. [MO]; Nelson & Gordon 5573, California, Trinity Co. [MO]) mention that the plants were growing on serpentine soil. The earliest collection of this species appears to be one made by Archibald Menzies in 1792–1794 under the name E. palustre (BM).

Crossostigma lindleyi Spach (a substitute name for Epilobium minutum) and E. lindleyi (Spach) Rydberg are illegitimate names that pertain here.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Epilobium septentrionale is endemic to northern California, found only in the drainages of the Eel, Mattole, and Trinity rivers in Humboldt, Mendocino, and Trinity counties. The dimorphic pattern of vestiture on this species (eglandular, white-canescent lower leaves versus glandular puberulent upper leaves and bracts) is highly distinctive and not found in any specimens of E. canum. Most collections are relatively uniform in aspect, leaves, flowers, fruits, and seeds, despite the relative isolation from one another in the different river drainages where they occur.

S. R. Seavey and P. H. Raven (1977c) reported an experimental hybrid between Epilobium septentrionale and diploid E. canum subsp. canum; although it had normal chromosome pairing, pollen fertility was reduced (51%).

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source FNA vol. 10. FNA vol. 10.
Parent taxa Onagraceae > subfam. Onagroideae > tribe Epilobieae > Epilobium > sect. Crossostigma Onagraceae > subfam. Onagroideae > tribe Epilobieae > Epilobium > sect. Zauschneria
Sibling taxa
E. anagallidifolium, E. arcticum, E. brachycarpum, E. campestre, E. canum, E. ciliatum, E. clavatum, E. cleistogamum, E. coloratum, E. davuricum, E. densiflorum, E. densum, E. foliosum, E. glaberrimum, E. hallianum, E. hirsutum, E. hornemannii, E. howellii, E. lactiflorum, E. leptocarpum, E. leptophyllum, E. luteum, E. mirabile, E. montanum, E. nevadense, E. nivium, E. obcordatum, E. obscurum, E. oreganum, E. oregonense, E. pallidum, E. palustre, E. parviflorum, E. rigidum, E. saximontanum, E. septentrionale, E. siskiyouense, E. smithii, E. suffruticosum, E. torreyi
E. anagallidifolium, E. arcticum, E. brachycarpum, E. campestre, E. canum, E. ciliatum, E. clavatum, E. cleistogamum, E. coloratum, E. davuricum, E. densiflorum, E. densum, E. foliosum, E. glaberrimum, E. hallianum, E. hirsutum, E. hornemannii, E. howellii, E. lactiflorum, E. leptocarpum, E. leptophyllum, E. luteum, E. minutum, E. mirabile, E. montanum, E. nevadense, E. nivium, E. obcordatum, E. obscurum, E. oreganum, E. oregonense, E. pallidum, E. palustre, E. parviflorum, E. rigidum, E. saximontanum, E. siskiyouense, E. smithii, E. suffruticosum, E. torreyi
Synonyms E. minutum var. canescens Zauschneria septentrionalisd., E. canum subsp. septentrionale
Name authority Lindley in W. J. Hooker: Fl. Bor.-Amer. 1: 207. (1832) (D. D. Keck) R. N. Bowman & Hoch: Ann. Missouri Bot. Gard. 66: 897. (1980)
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