Trifolium macrocephalum |
Trifolium willdenovii |
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big-head clover, large-head clover |
sand clover, thimble clover, tomcat clover, Willdenow's clover |
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Habit | Herbs perennial, 5–25 cm, villous. | Herbs annual, 10–60 cm, glabrous. |
Stems | erect or ascending, branched. |
erect, branched. |
Leaves | palmate; stipules ovate, obovate, or oblong, 1–3 cm, margins entire, irregularly lobed, or serrate, apex acute or acuminate; petiole 1–14 cm; petiolules 0.9–1.2 mm; leaflets (5–)7–9, blades broadly to narrowly obovate, often folded, 1–2.7 × 0.4–1.1 cm, base cuneate, veins thickened, especially distally, margins serrulate, apex rounded or truncate, apiculate, surfaces villous abaxially, sparsely villous to glabrate adaxially. |
palmate; stipules lanceolate or ovate, 1–2 cm, margins dentate or lacerate, apex acuminate; petiole 1–8 cm; petiolules 0.5 mm; leaflets 3, blades linear, lanceolate, or elliptic, 1–5 × 0.2–1.5 cm, base cuneate, veins fine, margins serrate, apex acute, blunt, or retuse, surfaces glabrous. |
Inflorescences | terminal, 20–32-flowered, globose or ovoid-ellipsoid, 2.5–8 × 3–7 cm; involucres absent. |
axillary or terminal, 10–50-flowered, globose or ovoid, 1–3.5 × 1–3 cm; involucres flattened or bowl-shaped, 3–9 mm, when folded, not hiding flowers except proximally, incised 1/4–1/3 their length. |
Peduncles | 2–8 cm. |
2–15 cm. |
Pedicels | erect, 1–1.5 mm; bracteoles broadly ovate, membranous, to 0.5 mm, truncate. |
erect, 0.5 mm; bracteoles absent. |
Flowers | 20–30 mm; calyx campanulate, 10–22 mm, villous, veins 10–15, tube 2.5–4 mm, lobes subequal, subulate, plumose, orifice open; corolla white, creamy white, or pinkish, keel petals deep pink, 20–28 mm, banner ovate or oblong, 20–28 × 10–13 mm, apex rounded or slightly emarginate. |
12–20 mm; calyx tubular-campanulate, slit between adaxial lobes, 6–9 mm, glabrous, veins 10–15, tube 3–7 mm, lobes unequal, triangular or subulate, usually 3-fid or shouldered below apex, orifice open; corolla usually white with purple spot, sometimes lavender or pink or all white, 10–18 mm, banner narrowly oblong, 12–20 × 3–4 mm, apex obtuse or retuse. |
Legumes | ovoid, 4–5 mm. |
ellipsoid, 3 mm. |
Seeds | 1 or 2, yellow or reddish, mitten-shaped to ellipsoid, 2.5–3 mm, smooth. |
1 or 2, yellow, mottled, globose-ellipsoid, 1.5–2.5 mm, smooth. |
2n | = 32, 48. |
= 16. |
Trifolium macrocephalum |
Trifolium willdenovii |
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Phenology | Flowering Apr–Jun. | Flowering Mar–Jul. |
Habitat | Rocky places, hard, compacted clay-gumbo, lava beds, sage-covered slopes, full sun. | Roadsides, meadows, lawns, hillsides, stream margins, open oak chaparral. |
Elevation | 80–2500 m. [260–8200 ft.] | 0–2500 m. [0–8200 ft.] |
Distribution |
CA; ID; NV; OR; WA
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AZ; CA; ID; OR; WA; BC; Mexico (Baja California)
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Discussion | Trifolium macrocephalum has the largest inflorescences of any clover. Trifolium megacephalum Nuttall (1818) is an illegitimate replacement name for Lupinaster macrocephalum Pursh. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Trifolium willdenovii was described by M. Zohary and D. Heller (1984) as one of the most variable clover species in North America. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 11. | FNA vol. 11. |
Parent taxa | ||
Sibling taxa | ||
Synonyms | Lupinaster macrocephalum | T. involucratum, T. aciculare, T. nuttallii, T. scabrellum, T. segetum, T. tridentatum, T. tridentatum var. aciculare, T. tridentatum var. scabrellum, T. tridentatum var. segetum, T. tridentatum var. watsonii, T. trimorphum, T. watsonii |
Name authority | (Pursh) Poiret in J. Lamarck et al.: Encycl., suppl. 5: 336. (1817) | Sprengel: Syst. Veg. 3: 208. (1826) |
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