Trifolium dubium |
Trifolium parryi |
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least hop clover, lesser hop clover, lesser hop trefoil, little hop clover, shamrock, small hop-clover, suckling clover |
Parry's clover |
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Habit | Herbs annual, 20–40 cm, glabrous or sparsely hairy. | Herbs perennial, 10–20 cm, glabrous. | ||||||||
Stems | erect to prostrate, branched from base. |
erect or ascending, loosely cespitose, sometimes rhizomatous, sparsely branched. |
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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 oblong, 0.5–2 cm, margins entire, apex acute to short-acuminate; petiole 2–10 cm; petiolules 0.5 mm; leaflets 3, blades elliptic to obovate, 1–4.1 × 0.5–1.6 cm, base cuneate, veins fine, margins entire, serrulate, or dentate, apex usually acute or obtuse, rarely retuse or apiculate, surfaces glabrous. |
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Inflorescences | axillary or terminal, 5–20-flowered, ovoid or globose, 0.5–0.9 × 0.6 cm; involucres absent. |
terminal, 15–20-flowered, globose, ovoid, or ellipsoid, 1.4–3.7 × 1.8–3 cm; involucres formed of distinct or connate bracteoles, apex acute or obtuse. |
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Peduncles | 1–1.5 cm. |
2.5–15 cm. |
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Pedicels | reflexed, 0.2–0.5 mm; bracteoles a fringe of red setae. |
erect, reflexed slightly, or only those of proximal flowers reflexed, 1 mm; bracteoles purplish, oblong, 3–6 mm, scarious. |
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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. |
12–22 mm; calyx campanulate, slightly gibbous, 6–9 mm, glabrous, veins 10, tube 3–4 mm, lobes unequal, subulate to narrowly triangular, orifice open; corolla pale purplish violet, keel petals darker purple, 10–22 mm, banner broadly elliptic or obovate, 10–22 × 8–10 mm, apex rounded, acute, or retuse. |
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Legumes | stipitate, ellipsoid, 1.5–2 mm, short beaked. |
stipitate, oblong, 6–7 mm. |
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Seeds | 1, yellow or pale brown, ellipsoid, 0.9–1 mm, smooth, glossy. |
1–4, tan or brown, mitten-shaped, 1.5–2 mm, smooth, dull. |
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2n | = 16, 28, 32. |
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Trifolium dubium |
Trifolium parryi |
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Phenology | Flowering May–Oct. | |||||||||
Habitat | Disturbed ground, fields. | |||||||||
Elevation | 0–2300 m. (0–7500 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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w United States
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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.) |
Subspecies 3 (3 in the flora). Subdivision of Trifolium parryi into three subspecies (J. M. Gillett 1965) or two varieties (D. Isely 1998) was rejected by R. C. Barneby (1989). (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 | Fabaceae > subfam. Faboideae > Trifolium | Fabaceae > subfam. Faboideae > Trifolium | ||||||||
Sibling taxa | ||||||||||
Subordinate taxa | ||||||||||
Synonyms | Chrysaspis dubia, T. minus | |||||||||
Name authority | Sibthorp: Fl. Oxon., 231. (1794) | A. Gray: Amer. J. Sci. Arts, ser. 2, 33: 409. (1862) | ||||||||
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