Trifolium macraei |
Trifolium subterraneum |
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Chilean clover, Macrae's clover |
burrowing clover, subclover, subterranean clover, subterranean trefoil |
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Habit | Herbs annual, 3–30 cm, pubescent. | Herbs annual, 10–80 cm, glabrous or appressed-pubescent. |
Stems | erect, ascending, or prostrate, branched. |
prostrate to ascending, branched. |
Leaves | 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. |
palmate; stipules ovate, 0.5–3 cm, margins entire or slightly toothed, ciliate, apex acute to acuminate; petiole 1–20 cm; petiolules 1 mm; leaflets 3, blades broadly obcordate, 0.8–2.8 × 1–3 cm, base cuneate, veins delicate, widely spaced, margins mostly entire, slightly dentate distally, apex emarginate, surfaces appressed-sericeous. |
Inflorescences | 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. |
axillary, elongate and reflexed, pushing into substrate after anthesis, fertile flowers 2–7, sterile flowers 0–80, globose or cylindric, 0.5–1.5 × 0.8–1.5 cm; involucres absent. |
Peduncles | 0–0.2 cm. |
2–6.5 cm. |
Pedicels | absent; bracteoles broadly ovate to linear, 1–2 mm. |
reflexed after anthesis, 0.2–0.4 mm; bracteoles absent. |
Flowers | 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. |
fertile ones 7–15 mm; calyx tubular, 5–6 mm, glabrous or hairy, veins indistinct, tube 3–4 mm, lobes subequal, pubescent or glabrous, spreading, orifice open; corolla white, pink, or pink-striped, 7–10 mm, banner ovate-elliptic, 7–10 × 1.5–2 mm, apex rounded; sterile flowers 4–7 mm; calyx teeth linear; corolla absent. |
Legumes | oblong, 2.5–3 mm. |
subterranean, obovoid, 3–4 mm. |
Seeds | 1, yellow, mottled, ellipsoid, 1.6–2 mm, smooth. |
1, purplish black, ellipsoid, 2.6–3 mm, smooth, dull. |
2n | = 16. |
= 16. |
Trifolium macraei |
Trifolium subterraneum |
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Phenology | Flowering May–Jun. | Flowering Mar–May. |
Habitat | Grassy fields, sandy ocean bluffs. | Open, disturbed sandy soils. |
Elevation | 0–800 m. (0–2600 ft.) | 0–1000 m. (0–3300 ft.) |
Distribution |
CA; OR; South America (Chile)
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CA; GA; LA; MA; MS; NC; NJ; OR; SC; WA; BC; w Europe; w Asia; n Africa [Introduced in North America; introduced also in s South America, s Africa, Pacific Islands (Hawaii, New Zealand), Australia]
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Discussion | 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.) |
Trifolium subterraneum was first introduced by the USDA about 1921 as a pasture crop; it is utilized as such in the western and southern United States (W. S. McGuire 1985). Inflorescences of T. subterraneum consist of intermixed sterile and fertile flowers; after fetilization, the inflorescence is pushed underground, where the fruits develop. (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 | T. bicephalum, T. catalinae, T. mercedense, T. traskiae | |
Name authority | Hooker & Arnott: Bot. Misc. 3: 179. (1833) | Linnaeus: Sp. Pl. 2: 767. (1753) |
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