Trifolium vesiculosum |
Trifolium microcephalum |
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arrow-leaf clover |
small-head clover |
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Habit | Herbs annual, 15–70 cm, glabrous. | Herbs annual, 3–55 cm, densely to sparsely pubescent. |
Stems | erect or ascending, branched. |
erect to ascending, branched. |
Leaves | palmate; stipules linear-lanceolate, 1–3.5 cm, margins entire, apex subulate or setaceous; petiole 0.5–10 cm; petiolules 1 mm; leaflet 3, blades obovate to oblong, elliptic or lanceolate, 0.5–4 × 0.5–1.5 cm, base cuneate, veins prominent, thickened, margins spinulose-denticulate, apex apiculate, surfaces glabrous. |
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. |
Inflorescences | terminal or axillary, 50–100+-flowered, globose, ovoid, or oblong, 3–6 × 2–3.5 cm; involucres absent. |
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. |
Peduncles | 1–12 cm. |
1–8 cm. |
Pedicels | absent; bracteoles lanceolate, 6–7 mm, acuminate. |
absent; bracteoles absent. |
Flowers | 12–16 mm; calyx urceolate, not bilabiate, inflated in fruit, 6–10 mm, glabrous, veins 20–36, connected by transverse veins in fruit, tube 3–5 mm, lobes reflexed, subequal, subulate, as long as tube, orifice constricted; corolla white becoming pink, 12–15 mm, banner ovate, broadly clawed, striate, 12–15 × 2–4 mm, apex acute-acuminate. |
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. |
Legumes | ellipsoid, 2.5–2.5 mm, shorter than calyx. |
broadly ellipsoid, 1.5–2 mm. |
Seeds | 2 or 3, brown, ovoid, 1–1.5 mm, roughened. |
1, yellow, reddish mottled, oblong, 1.5 mm, smooth. |
2n | = 16. |
= 16. |
Trifolium vesiculosum |
Trifolium microcephalum |
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Phenology | Flowering Apr–Jul. | Flowering Mar–Jul. |
Habitat | Fields, roadsides, forest openings. | Meadows, roadsides, stream banks, forest clearings, grassy slopes. |
Elevation | 0–1000 m. (0–3300 ft.) | 0–2500 m. (0–8200 ft.) |
Distribution |
AL; AR; CA; FL; GA; LA; MA; MO; MS; OK; OR; SC; TX; VA; WA; s Europe; e Europe; w Asia [Introduced in North America]
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AK; AZ; CA; ID; MT; NV; OR; WA; BC; Mexico (Baja California)
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Discussion | Trifolium vesiculosum was first introduced into cultivation in the United States in 1963 and is grown in southern and western states (J. D. Miller and H. D. Wells 1985). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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.) |
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 | |
Name authority | Savi: Fl. Pis. 2: 165. (1798) — (as vessiculosum) | Pursh: Fl. Amer. Sept. 2: 478. (1813) |
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