Trifolium amoenum |
Trifolium macraei |
|
---|---|---|
showy Indian clover, two-fork clover |
Chilean clover, Macrae's clover |
|
Habit | Herbs annual, 45–65 cm, canescent. | Herbs annual, 3–30 cm, pubescent. |
Stems | erect, branched from base and distally, or unbranched. |
erect, ascending, or prostrate, 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. |
palmate; stipules ovate to oblong, 0.6–1 cm, margins entire, apex acuminate to cuspidate; petiole 0.5–6 cm; petiolules to 0.5 mm; leaflets 3, blades obovate, oblanceolate, or elliptic, 0.6–1.6 × 0.3–1.2 cm, base cuneate, veins obscure or slightly thickened, margins subentire to serrate, apex rounded, retuse, surfaces pubescent. |
Inflorescences | terminal or axillary, 30–50-flowered, bluntly conic, ellipsoid, globose, or subglobose, 1.5–3 × 1.5–2.5 cm; involucres absent. |
terminal or subterminal, usually paired, sometimes one head slightly stalked, partially hidden by terminal leaves and stipules, 10–40-flowered, ovoid or subglobose, 0.8–2.5 × 0.5–2 cm; involucres absent, involucrelike structure formed from terminal leaves and stipules. |
Peduncles | 5–15 cm. |
0–0.2 cm. |
Pedicels | absent; bracteoles cuplike, to 0.5 mm. |
absent; bracteoles broadly ovate to linear, 1–2 mm. |
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. |
5.5–7.5 mm; calyx tubular, 4–5 mm, pubescent, veins 5–10, tube 1.5–2 mm, lobes subequal, subulate, orifice open; corolla usually purple or pink, rarely white, 5–7 mm, banner obovate-oblong, 6–7 × 2–3 mm, apex rounded, slightly denticulate. |
Legumes | obovoid, 4 mm. |
oblong, 2.5–3 mm. |
Seeds | 1, dark brown, ellipsoid, 2–3 mm, smooth. |
1, yellow, mottled, ellipsoid, 1.6–2 mm, smooth. |
2n | = 16. |
|
Trifolium amoenum |
Trifolium macraei |
|
Phenology | Flowering Apr–May. | Flowering May–Jun. |
Habitat | Grassy slopes, swales, clay soils. | Grassy fields, sandy ocean bluffs. |
Elevation | 0–100 m. (0–300 ft.) | 0–800 m. (0–2600 ft.) |
Distribution |
CA
|
CA; OR; South America (Chile)
|
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 macraei was described from specimens collected in Chile; the South American plants have broader banners, smaller auricles on the wing petals, and styles that are barely curved upwards distally (D. Isely 1998). Further examination of the disjunct populations may reveal other differences and prompt reconsideration of the identity of North American specimens. The record from Massachusetts is a waif. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 11. | FNA vol. 11. |
Parent taxa | ||
Sibling taxa | ||
Synonyms | T. bicephalum, T. catalinae, T. mercedense, T. traskiae | |
Name authority | Greene: Fl. Francisc., 27. (1891) | Hooker & Arnott: Bot. Misc. 3: 179. (1833) |
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