Trifolium macrocephalum |
Trifolium pratense |
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big-head clover, large-head clover |
red clover |
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Habit | Herbs perennial, 5–25 cm, villous. | Herbs perennial, 20–70 cm, pilose or glabrous. |
Stems | erect or ascending, branched. |
erect, ascending, or decumbent, 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 broadly triangular, 1–2 cm, margins entire, sometimes ciliate, apex mucronate or setaceous; petiole 1–9 cm; petiolules 1 mm; leaflets 3, blades elliptic to obovate, 1.5–5 × 0.7–1.5 cm, base cuneate, veins prominent, margins subentire, apex obtuse, acute, or retuse, surfaces appressed-pubescent. |
Inflorescences | terminal, 20–32-flowered, globose or ovoid-ellipsoid, 2.5–8 × 3–7 cm; involucres absent. |
terminal, solitary or paired, 75–100+-flowered, globose or ovoid, 1.2–7.7 × 0.7–2.2 cm; involucres absent, involucrelike structures formed of stipules of distalmost leaves. |
Peduncles | 2–8 cm. |
± 0 cm, subtended by stipules of distal leaves. |
Pedicels | erect, 1–1.5 mm; bracteoles broadly ovate, membranous, to 0.5 mm, truncate. |
straight, 0–1 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. |
15–18 mm; calyx tubular-campanulate, 8–11 mm, hairy, veins 10, tube 3–4 mm, lobes unequal, adaxial equaling tube, lateral and abaxial 2 times tube, orifice hairy, slightly closed; corolla usually rose-purple, rarely pink or white, 13–18 mm, banner elliptic-ovate, 10–13 × 3–5 mm, apex narrowly rounded. |
Legumes | ovoid, 4–5 mm. |
oblong, leathery distally, transversely dehiscent, 3 mm. |
Seeds | 1 or 2, yellow or reddish, mitten-shaped to ellipsoid, 2.5–3 mm, smooth. |
1 or 2, yellow, yellow-brown, or purple, ovoid, 1.6–2 mm, smooth, dull. |
2n | = 32, 48. |
= 14. |
Trifolium macrocephalum |
Trifolium pratense |
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Phenology | Flowering Apr–Jun. | Flowering May–Sep. |
Habitat | Rocky places, hard, compacted clay-gumbo, lava beds, sage-covered slopes, full sun. | Fields, prairies, roadsides, disturbed areas. |
Elevation | 80–2500 m. [260–8200 ft.] | 0–3100 m. [0–10200 ft.] |
Distribution |
CA; ID; NV; OR; WA
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AK; AL; AR; AZ; CA; CO; CT; DC; DE; FL; GA; IA; ID; IL; IN; KS; KY; LA; MA; MD; ME; MI; MN; MO; MS; MT; NC; ND; NE; NH; NJ; NM; NV; NY; OH; OK; OR; PA; RI; SC; SD; TN; TX; UT; VA; VT; WA; WI; WV; WY; AB; BC; MB; NB; NL; NS; NT; ON; PE; QC; SK; YT; SPM; Greenland; Eurasia [Introduced in North America; introduced also in s South America, s Africa, Pacific Islands (Hawaii, New Zealand), Australia]
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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 pratense is morphologically variable and numerous varieties have been recognized (M. Zohary and D. Heller 1984). Distinctions among these are slight and intergradation is common, perhaps due to the long-time cultivation of the species. In North America, the following varieties are sometimes recognized: var. pratense with stems decumbent to ascending, 20–40 cm, with dense, appressed, white hairs; var. sativum Schreber with stems mostly erect, 40–100 cm, sparsely hairy or glabrous; and var. americanum Harz with stems 30–100 cm, with dense, spreading hairs. (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. pensylvanicum |
Name authority | (Pursh) Poiret in J. Lamarck et al.: Encycl., suppl. 5: 336. (1817) | Linnaeus: Sp. Pl. 2: 768. (1753) |
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