Trifolium eriocephalum |
Trifolium sonorense |
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woolly-head clover |
Sonoran clover |
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Habit | Herbs perennial, 12–46 cm, sparsely hairy to densely villous, appressed-pubescent, or glabrate. | Herbs perennial, 25–38+ cm, pubescent. | ||||||||||||||||||||
Stems | erect or decumbent, branched. |
prostrate, branched. |
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Leaves | palmate; stipules lanceolate or ovate, 1–5 cm, margins entire or denticulate, apex acuminate or acute; petiole 1–15 cm; petiolules 1 mm; leaflets 3, blades linear, linear-elliptic, elliptic, lanceolate, lanceolate-oblong, or obovate, 1–5 × 0.4–1.2 cm, base cuneate, veins fine or ± thickened, margins denticulate or serrulate, apex acuminate or acute, surfaces appressed-pubescent abaxially, glabrous, densely villous, or sparsely or densely pilose adaxially. |
palmate; stipules narrowly triangular, 0.7–1.7 cm, margins entire or finely serrulate, apex usually acute or acuminate, sometimes 2-fid; petiole 0.3–5 cm; petiolules to 1 mm; leaflets 3, blades obovate to obcordate, 0.9–1.6 × 0.7–1.2 cm, base cuneate, veins moderately thickened, margins serrate to weakly so, apex rounded or emarginate, mucronulate, surfaces slightly hairy abaxially, glabrous adaxially. |
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Inflorescences | terminal or axillary, 25–70-flowered, inverted or horizontal, ellipsoid or globose to subglobose, 2–3 × 1–3 cm, rachis prolonged beyond flowers; involucres absent. |
axillary, 10–20-flowered, depressed-globose or globose, 0.8–1.6 × 0.9–1.6 cm, rachis prolonged beyond flowers; involucres a narrow rim, or slightly proximally connate bracteoles of proximal flowers, 0.1–0.5 mm. |
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Peduncles | bent distally, proximal to flowers, 3–18 cm. |
2.8–5 cm. |
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Pedicels | reflexed, to 0.3 mm; bracteoles absent. |
reflexed in fruit, 1–3 mm; bracteoles linear-triangular, 0.5 mm. |
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Flowers | 9–18 mm; calyx campanulate, curved in fruit, 4–11 mm, villous, veins 10, tube 1.5–2.5 mm, lobes unequal, 2–3 times tube, subulate, often strongly curved and twisted, plumose, orifice open; corolla white, cream, or purple, 8–16 mm, banner oblanceolate, 8–16 × 3–5 mm, apex rounded or retuse, recurved; ovaries pubescent distally. |
5.7–6.7 mm; calyx tubular, 3.3–6.5 mm, pubescent, veins 10, tube 0.8–1 mm, lobes subequal, narrowly triangular, orifice open; corolla white or pink, 5.3–6.5 mm, banner obovate, 5.3–6.5 × 2.8–3.8 mm, apex broadly rounded or broadly acute. |
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Legumes | ovoid, 2–3.5 mm. |
obovoid, 4.3–4.4 mm. |
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Seeds | (1 or)2–4, yellow-brown to brown, mitten-shaped or subglobose, 1.2–2 mm, smooth. |
2, brownish orange or olive-brown, globose or broadly reniform, 1.2–1.7 mm, smooth. |
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2n | = 16. |
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Trifolium eriocephalum |
Trifolium sonorense |
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Phenology | Flowering Aug–Oct. | |||||||||||||||||||||
Habitat | Dry stream banks, grassy places. | |||||||||||||||||||||
Elevation | 1500–1800 m. [4900–5900 ft.] | |||||||||||||||||||||
Distribution |
w United States
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AZ; Mexico (Chihuahua, Jalisco, Sinaloa, Sonora) |
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Discussion | Subspecies 6 (6 in the flora). Trifolium eriocephalum was revised by J. M. Gillett (1971). The subspecies exhibit unusually complex distributional patterns, and overlapping morphological features sometimes make identifications problematic (M. Zohary and D. Heller 1984). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Trifolium sonorense has long been equated with T. amabile Kunth, from which T. K. Ahlquist (2012) and also Ahlquist & M. A. Vincent have shown it to be distinct by longer sepal lobes (more than 3 mm), keel petal claws (more than 1.7 mm), and filament tubes (more than 3.6 mm). Trifolium sonorense is known from western Mexico and southernmost Arizona (Cochise County), largely in the Sonoran Desert region, and in mountainous Jalisco. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 11. | FNA vol. 11. | ||||||||||||||||||||
Parent taxa | ||||||||||||||||||||||
Sibling taxa | ||||||||||||||||||||||
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Name authority | Nuttall in J. Torrey and A. Gray: Fl. N. Amer. 1: 313. (1838) | T. K. Ahlquist & Vincent: Phytoneuron 2018-1: 1, fig. 1. (2018) | ||||||||||||||||||||
Web links |