Trifolium amoenum |
Trifolium campestre |
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showy Indian clover, two-fork clover |
field clover, hop clover, hop trefoil, low hop-clover, pinnate hop clover |
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Habit | Herbs annual, 45–65 cm, canescent. | Herbs annual, 5–40 cm, slightly villous or glabrous. |
Stems | erect, branched from base and distally, or unbranched. |
erect to ascending, branched. |
Leaves | palmate; stipules ovate-oblong, 0.5–1.8 cm, margins entire, toothed, or irregularly lobed, apex acuminate; petiole 0.5–10 cm; petiolules to 1 mm; leaflets 3, blades broadly obovate or elliptic, 1.7–3.3 × 1.1–2 cm, base cuneate, veins fine, margins entire or denticulate, apex rounded, obtuse, or retuse, surfaces pilose, abaxial less so. |
pinnate; stipules ovate-lanceolate, 0.5–0.8 cm, margins entire, glandular, apex acuminate; petiole 0.3–2 cm; lateral leaflet petiolules 0.5–0.6 mm, terminal leaflet stalk 3–5 mm; leaflets 3, blades rhombic to obovate, 0.4–1.5 × 0.4–0.8 cm, base cuneate, lateral veins prominent, ± parallel, ascending, margins denticulate distally, apex truncate or retuse, surfaces strigose adaxially. |
Inflorescences | terminal or axillary, 30–50-flowered, bluntly conic, ellipsoid, globose, or subglobose, 1.5–3 × 1.5–2.5 cm; involucres absent. |
axillary, 30–60-flowered, globose or broadly ovoid, 0.8–1.5 × 0.7–1 cm; involucres absent. |
Peduncles | 5–15 cm. |
1.5–3.5 cm. |
Pedicels | absent; bracteoles cuplike, to 0.5 mm. |
reflexed, 0.7–1.2 mm; bracteoles a fringe of red setae. |
Flowers | 13–16 mm; calyx tubular, 9–12 mm, pubescent, veins 20–30, tube 3 mm, lobes nearly equal, appearing rigidly erect, linear-setaceous, plumose, sinuses acute, orifice open; corolla white to pink with purple tips, 12–16 mm, banner ovate-oblong, 12–15 × 4 mm, apex broadly rounded, emarginate. |
4.3–5 mm; calyx campanulate, strongly bilabiate, 1.3–1.5 mm, glabrous, veins 5, tube 0.3–0.6 mm, lobes unequal, adaxial deltate, very short, lateral and abaxial linear-subulate, each tipped with 1 or 2 stiff hairs, orifice open; corolla yellow becoming brown, 3.5–6 mm, ribbed, banner persistent, obovate, enveloping other petals, boat-shaped, 4.3–5 × 2.8–3.2 mm, apex broad, acute. |
Legumes | obovoid, 4 mm. |
stipitate, oblong, 2–2.5 mm. |
Seeds | 1, dark brown, ellipsoid, 2–3 mm, smooth. |
1 or 2, yellow, ellipsoid, 1–1.5 mm, smooth, lustrous. |
2n | = 14. |
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Trifolium amoenum |
Trifolium campestre |
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Phenology | Flowering Apr–May. | Flowering Jun–Aug. |
Habitat | Grassy slopes, swales, clay soils. | Roadsides, fields. |
Elevation | 0–100 m. (0–300 ft.) | 0–1700 m. (0–5600 ft.) |
Distribution |
CA
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AK; AL; AR; AZ; CA; 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; NY; OH; OK; OR; PA; RI; SC; TN; TX; VA; VT; WA; WI; WV; WY; BC; NB; NF; NS; ON; PE; QC; SPM; Europe; w Asia; n Africa [Introduced in North America; introduced also in South America, e Asia (China), s Africa, Pacific Islands (Hawaii, New Zealand), Australia]
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Discussion | Trifolium amoenum was considered extinct (J. P. Smith Jr. 1984) but was rediscovered in 1993 (P. G. Connors 1994). Specimens of T. amoenum are known from Marin, Napa, San Mateo, Solano, and Sonoma counties; it appears to be extant in only single populations in each of Marin and Solano counties. Allozyme studies of the two known populations revealed fixed genetic differences between them (E. E. Knapp and Connors 1999). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Trifolium filiforme Linnaeus and T. procumbens Linnaeus are rejected names that were used historically for T. campestre (J. E. Dandy 1958; N. J. Turland et al. 1996). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 11. | FNA vol. 11. |
Parent taxa | ||
Sibling taxa | ||
Synonyms | Chrysaspis campestris | |
Name authority | Greene: Fl. Francisc., 27. (1891) | Schreber in G. F. Hoffmann: Deutschl. Fl. 4: 16, plate 253. (1804) |
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