Trifolium dubium |
Trifolium breweri |
|
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least hop clover, lesser hop clover, lesser hop trefoil, little hop clover, shamrock, small hop-clover, suckling clover |
Brewer's clover, forest clover |
|
Habit | Herbs annual, 20–40 cm, glabrous or sparsely hairy. | Herbs perennial, 5–50 cm, glaucous, sparsely appressed-pubescent. |
Stems | erect to prostrate, branched from base. |
erect or ascending, branched. |
Leaves | pinnate; stipules ovate, 0.3–0.5 cm, margins entire, apex acute; petiole to 1.5 cm; lateral leaflet petiolules to 0.5 mm, terminal leaflet stalk 1–1.5 mm; leaflets 3, blades obovate to elliptic-lanceolate, 1–2 × 0.5–1.5 cm, base cuneate, lateral veins prominent, ± parallel, ascending, margins dentate distally, apex rounded or retuse, surfaces glabrous or sparsely hairy. |
palmate; stipules lanceolate to narrowly ovate, 0.3–1 cm, margins entire, apex long-acuminate; petiole 0.3–4 cm; petiolules 0.5 mm; leaflets 3, blades obovate to obcordate, 0.3–1.5 × 0.3–1.2 cm, base cuneate, veins thickened, recurved, margins dentate, apex obtuse or emarginate, surfaces sparsely hairy abaxially, glabrous adaxially. |
Inflorescences | axillary or terminal, 5–20-flowered, ovoid or globose, 0.5–0.9 × 0.6 cm; involucres absent. |
axillary, 5–25-flowered, globose, 1.3–1.5 × 1.3–1.5 cm; involucres absent. |
Peduncles | 1–1.5 cm. |
geniculate proximal to flowers, inflorescence appearing inverted, 3–5 cm. |
Pedicels | reflexed, 0.2–0.5 mm; bracteoles a fringe of red setae. |
strongly reflexed in fruit, 2–3 mm; bracteoles minute. |
Flowers | 2.8–3.5 mm; calyx campanulate, 1.5–2 mm, glabrous, veins 5, tube 0.8–1 mm, lobes unequal, longer than tube, adaxial 2 shorter, orifice open; corolla pale yellow becoming brown, 2.6–3.2 mm, not or slightly ribbed, banner persistent, spatulate, 2.6–3.2 × 2 mm, apex rounded to broadly acute. |
11–13 mm; calyx tubular, 6–8 mm, pilose or glabrous, veins 10, tube 1.5–2 mm, lobes subequal, subulate, orifice open; corolla rose-pink or creamy white, 6–10 mm, banner ovate-oblong, 6–10 × 3 mm, equaling wing and keel petals, apex rounded or emarginate. |
Legumes | stipitate, ellipsoid, 1.5–2 mm, short beaked. |
short-stipitate, ovoid-ellipsoid, 7–10 mm. |
Seeds | 1, yellow or pale brown, ellipsoid, 0.9–1 mm, smooth, glossy. |
1 or 2, brown, ovoid-ellipsoid, 2.5–3 mm, smooth. |
2n | = 16, 28, 32. |
= 16. |
Trifolium dubium |
Trifolium breweri |
|
Phenology | Flowering May–Oct. | Flowering May–Aug. |
Habitat | Disturbed ground, fields. | Wooded areas, roadsides, mixed evergreen or pine forests. |
Elevation | 0–2300 m. (0–7500 ft.) | 1000–2200 m. (3300–7200 ft.) |
Distribution |
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; NV; NY; OH; OK; OR; PA; RI; SC; TN; TX; VA; VT; WA; WI; WV; WY; BC; NB; NS; ON; PE; QC; SPM; c Europe; s Europe; w Asia [Introduced in North America; introduced also in s South America, e Asia (e China), n, s Africa, Pacific Islands (Hawaii, New Zealand), Australia]
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CA; OR; Mexico (Baja California)
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Discussion | Trifolium dubium is often confused with Medicago lupulina Linnaeus; the latter may be distinguished by its toothed stipules, deciduous corollas, and shiny, black fruits. Little hop clover may be the co-called shamrock of Irish folklore (E. C. Nelson 1991; P. S. Wyse Jackson 2014); other candidates include other species of Trifolium or species of Medicago or Oxalis. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Trifolium breweri, which ranges from Madera County, California, northward to Josephine County, Oregon, is also reported from Baja California, Mexico. It was considered by J. S. Martin (1943) to be remarkably morphologically uniform; F. E. Clements (1920) termed it a foundational species in the Sierran Montane Forest Pinus Association climax formation. (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 | Chrysaspis dubia, T. minus | |
Name authority | Sibthorp: Fl. Oxon., 231. (1794) | S. Watson: Proc. Amer. Acad. Arts 11: 131. (1876) |
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