Trifolium microcephalum |
Trifolium latifolium |
|
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small-head clover |
broad-leaf clover, twin clover |
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Habit | Herbs annual, 3–55 cm, densely to sparsely pubescent. | Herbs perennial, 4–40 cm, appressed-pubescent. |
Stems | erect to ascending, branched. |
ascending, branched from slender, rhizomatous crown. |
Leaves | palmate; stipules obliquely ovate, 0.4–1.2 cm, margins entire or slightly serrate, apex acuminate; petiole 1–5 cm; petiolules 0.5 mm; leaflets 3, blades oblanceolate, obovate, or obcordate, 0.4–1.7 × 0.3–1.1 cm, base cuneate, veins fine or slightly thickened, margins setose, often dentate distally, apex usually retuse, rarely rounded, surfaces villous. |
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 | axillary or terminal, 10–40-flowered, globose, 0.5–1.3 × 0.4–1.2 cm; involucres flattened or bowl-shaped, 0.4–1 cm, when folded, nearly completely hiding calyces, villous, incised 1/2 their length, lobes 5–12, lanceolate-ovate, entire or slightly toothed proximally, acuminate. |
terminal, 6–30-flowered, globose, 2.3–3.1 × 2–3 cm, rachis prolonged beyond flowers; involucres absent. |
Peduncles | 1–8 cm. |
bent proximal to flowers, inflorescence appearing inverted, 2.5–12 cm. |
Pedicels | absent; bracteoles absent. |
reflexed in fruit, 1.5–2 mm; bracteoles minute, scalelike, membranous, to 0.3 mm. |
Flowers | 4–6 mm; calyx campanulate-tubular, 3–5.5 mm, pubescent, veins 10, tube 1.8–2.5 mm, lobes ± equal, triangular-aristate, margins hyaline, wavy, orifice open; corolla white or pink to lavender, 4–6 mm, banner oblong, 3–6 × 1–2 mm, apex emarginate. |
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 | broadly ellipsoid, 1.5–2 mm. |
oblong to subglobose, 5 mm. |
Seeds | 1, yellow, reddish mottled, oblong, 1.5 mm, smooth. |
1 or 2, dark brown, ± globose, 1.2 mm, smooth. |
2n | = 16. |
= 16, 32. |
Trifolium microcephalum |
Trifolium latifolium |
|
Phenology | Flowering Mar–Jul. | Flowering May–Jul. |
Habitat | Meadows, roadsides, stream banks, forest clearings, grassy slopes. | Clearings in conifer forests, moist gravelly, rocky, or clay soils, grassy hillsides and gullies, prairies. |
Elevation | 0–2500 m. (0–8200 ft.) | 800–1500 m. (2600–4900 ft.) |
Distribution |
AK; AZ; CA; ID; MT; NV; OR; WA; BC; Mexico (Baja California)
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ID; MT; OR; WA
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Discussion | Trifolium microcephalum is common in much of its range in California and northward into Oregon, and is rare in much of the rest of its range. It is closely allied with the Chilean T. vernum Philippi (N. W. Ellison et al. 2006), which it resembles greatly, and from which it is distinguished by its shorter calyx lobes (M. Zohary and D. Heller 1984). (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 | ||
Synonyms | Lojaconoa microcephala, T. microcephalum var. bipedale, T. microcephalum var. lemmonii | T. longipes var. latifolium, T. aitonii, T. orbiculatum |
Name authority | Pursh: Fl. Amer. Sept. 2: 478. (1813) | (Hooker) Greene: Pittonia 3: 223. (1897) |
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