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canyon clover, Howell's clover

broad-leaf clover, twin clover

Habit Herbs perennial, 30–100 cm, glabrous. Herbs perennial, 4–40 cm, appressed-pubescent.
Stems

erect, fistulose, unbranched or branched distally.

ascending, branched from slender, rhizomatous crown.

Leaves

palmate;

stipules ovate, 1.5–4.5 cm, margins usually entire, sometimes lobed, apex acuminate;

petiole 0.5–20 cm;

petiolules 1–1.5 mm;

leaflets 3, blades ovate, elliptic, or rhombic, 3.5–9.5 × 2.3–5 cm, base cuneate, veins obscure, margins ± serrate, apex acute, rounded, or obtuse, surfaces glabrous.

palmate;

stipules ovate or lanceolate, 0.5–2 cm, margins entire proximally, 1–3-toothed distally, apex acuminate or acute;

petiole 1.5–10 cm;

petiolules to 1 mm;

leaflets 3, blades obovate or elliptic, 0.5–4.2 × 0.3–2.5 cm, base cuneate, veins fine or slightly thickened, margins serrulate, apex acute, rounded, or retuse, apiculate, surfaces appressed-pubescent.

Inflorescences

terminal or axillary, 20–70-flowered, globose or ellipsoid, 2.5–4 × 2–2.5 cm, rachis prolonged beyond flowers, undivided or forked, often bearing sterile flower buds distally;

involucres absent.

terminal, 6–30-flowered, globose, 2.3–3.1 × 2–3 cm, rachis prolonged beyond flowers;

involucres absent.

Peduncles

3–11 cm.

bent proximal to flowers, inflorescence appearing inverted, 2.5–12 cm.

Pedicels

strongly reflexed in fruit, 1 mm;

bracteoles minute, blunt or acute, membranous.

reflexed in fruit, 1.5–2 mm;

bracteoles minute, scalelike, membranous, to 0.3 mm.

Flowers

10–14 mm;

calyx campanulate, gibbous, 4–5.5 mm, glabrous, veins 10, tube 2–2.5 mm, lobes subequal, linear-lanceolate, orifice open;

corolla white, lemon yellow, or greenish yellow, 11–12 mm, banner elliptic-oblong, 11–12 × 4–5 mm, apex obtuse.

13–17 mm, sweetly fragrant;

calyx campanulate, 4.5–5 mm, appressed-pubescent, veins 5, tube 2 mm, lobes subequal, linear, orifice open;

corolla white, sometimes with purplish or buff-pink veins, 12–15 mm, banner elliptic, 12–15 × 4 mm, longer than wing and keel petals, apex tapered, sometimes retuse.

Legumes

oblong or clavate, 4–5 mm.

oblong to subglobose, 5 mm.

Seeds

1–3, reddish black or brown, angular, mitten-shaped, 2.5 mm, smooth or slightly roughened, dull.

1 or 2, dark brown, ± globose, 1.2 mm, smooth.

2n

= 16, 32.

Trifolium howellii

Trifolium latifolium

Phenology Flowering Jun–Jul. Flowering May–Jul.
Habitat Wet stream banks, wet meadows, flood plains, shady woodlands, springs, thickets. Clearings in conifer forests, moist gravelly, rocky, or clay soils, grassy hillsides and gullies, prairies.
Elevation 800–2000 m. (2600–6600 ft.) 800–1500 m. (2600–4900 ft.)
Distribution
from FNA
CA; OR
[WildflowerSearch map]
[BONAP county map]
from FNA
ID; MT; OR; WA
[WildflowerSearch map]
[BONAP county map]
Discussion

Trifolium howellii is known from Del Norte, Humboldt, Siskiyou, and Trinity counties in California, and Clackamas, Douglas, Jackson, Josephine, Klamath, Lane, and Linn counties in Oregon (J. M. Gillett 1972). It has some of the largest leaves of any species of Trifolium in North America.

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

Trifolium latifolium, which is found in northwestern Montana, northern Idaho, northeastern Oregon, and southeastern Washington, is morphologically allied to T. longipes (J. M. Gillett 1969) and molecular phylogenetic studies place it as sister to T. longipes (N. W. Ellison et al. 2006).

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

Source FNA vol. 11. FNA vol. 11.
Parent taxa Fabaceae > subfam. Faboideae > Trifolium Fabaceae > subfam. Faboideae > Trifolium
Sibling taxa
T. albopurpureum, T. alexandrinum, T. amoenum, T. amphianthum, T. andersonii, T. andinum, T. angustifolium, T. appendiculatum, T. arvense, T. attenuatum, T. aureum, T. barbigerum, T. barnebyi, T. beckwithii, T. bejariense, T. bifidum, T. bolanderi, T. brandegeei, T. breweri, T. buckwestiorum, T. calcaricum, T. campestre, T. carolinianum, T. cernuum, T. ciliolatum, T. columbinum, T. cyathiferum, T. dasyphyllum, T. dedeckerae, T. depauperatum, T. dichotomum, T. douglasii, T. dubium, T. echinatum, T. eriocephalum, T. fragiferum, T. friscanum, T. fucatum, T. glomeratum, T. gracilentum, T. grayi, T. gymnocarpon, T. haydenii, T. hirtum, T. hybridum, T. hydrophilum, T. incarnatum, T. jokerstii, T. kentuckiense, T. kingii, T. lappaceum, T. latifolium, T. leibergii, T. lemmonii, T. longipes, T. lupinaster, T. macilentum, T. macraei, T. macrocephalum, T. medium, T. microcephalum, T. microdon, T. monanthum, T. mucronatum, T. nanum, T. nigrescens, T. obtusiflorum, T. oliganthum, T. ornithopodioides, T. owyheense, T. palmeri, T. parryi, T. pinetorum, T. piorkowskii, T. plumosum, T. polyodon, T. pratense, T. productum, T. reflexum, T. repens, T. resupinatum, T. retusum, T. rollinsii, T. siskiyouense, T. sonorense, T. stoloniferum, T. striatum, T. subterraneum, T. suffocatum, T. thompsonii, T. tomentosum, T. trichocalyx, T. variegatum, T. vesiculosum, T. virginicum, T. willdenovii, T. wormskioldii
T. albopurpureum, T. alexandrinum, T. amoenum, T. amphianthum, T. andersonii, T. andinum, T. angustifolium, T. appendiculatum, T. arvense, T. attenuatum, T. aureum, T. barbigerum, T. barnebyi, T. beckwithii, T. bejariense, T. bifidum, T. bolanderi, T. brandegeei, T. breweri, T. buckwestiorum, T. calcaricum, T. campestre, T. carolinianum, T. cernuum, T. ciliolatum, T. columbinum, T. cyathiferum, T. dasyphyllum, T. dedeckerae, T. depauperatum, T. dichotomum, T. douglasii, T. dubium, T. echinatum, T. eriocephalum, T. fragiferum, T. friscanum, T. fucatum, T. glomeratum, T. gracilentum, T. grayi, T. gymnocarpon, T. haydenii, T. hirtum, T. howellii, T. hybridum, T. hydrophilum, T. incarnatum, T. jokerstii, T. kentuckiense, T. kingii, T. lappaceum, T. leibergii, T. lemmonii, T. longipes, T. lupinaster, T. macilentum, T. macraei, T. macrocephalum, T. medium, T. microcephalum, T. microdon, T. monanthum, T. mucronatum, T. nanum, T. nigrescens, T. obtusiflorum, T. oliganthum, T. ornithopodioides, T. owyheense, T. palmeri, T. parryi, T. pinetorum, T. piorkowskii, T. plumosum, T. polyodon, T. pratense, T. productum, T. reflexum, T. repens, T. resupinatum, T. retusum, T. rollinsii, T. siskiyouense, T. sonorense, T. stoloniferum, T. striatum, T. subterraneum, T. suffocatum, T. thompsonii, T. tomentosum, T. trichocalyx, T. variegatum, T. vesiculosum, T. virginicum, T. willdenovii, T. wormskioldii
Synonyms T. longipes var. latifolium, T. aitonii, T. orbiculatum
Name authority S. Watson: Proc. Amer. Acad. Arts 23: 262. (1888) (Hooker) Greene: Pittonia 3: 223. (1897)
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