Trifolium dubium |
Trifolium virginicum |
|
---|---|---|
least hop clover, lesser hop clover, lesser hop trefoil, little hop clover, shamrock, small hop-clover, suckling clover |
kates mountain clover |
|
Habit | Herbs annual, 20–40 cm, glabrous or sparsely hairy. | Herbs perennial, 3–10 cm, pilose. |
Stems | erect to prostrate, branched from base. |
cespitose, prostrate, branched from crown. |
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 oblanceolate to ovate, 1–1.5 cm, margins entire, apex acute-acuminate; petiole 5–10 cm; petiolules to 1 mm; leaflets 3, blades linear-elliptic, elliptic, narrowly oblong, or lanceolate, 1–7 × 0.4–1 cm, base cuneate, veins fine or thickened, margins entire or serrulate, apex truncate to acute, surfaces pubescent abaxially, glabrous adaxially. |
Inflorescences | axillary or terminal, 5–20-flowered, ovoid or globose, 0.5–0.9 × 0.6 cm; involucres absent. |
terminal or axillary, 20–40-flowered, becoming supine in fruit, globose, 1.5–3.5 × 1.5–3 cm; involucres absent. |
Peduncles | 1–1.5 cm. |
2–6 cm. |
Pedicels | reflexed, 0.2–0.5 mm; bracteoles a fringe of red setae. |
reflexed in fruit, 3–8 mm; bracteoles ovate or lanceolate-linear, to 1 mm. |
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. |
10–12 mm; calyx campanulate, 4–7 mm, pilose, veins 10, tube 1.5–3 mm, lobes equal, subulate, orifice open; corolla white, sometimes becoming pink to red, 10–12 mm, banner obovate-oblong, 10–12 × 4–5 mm, apex rounded, retuse or mucronate. |
Legumes | stipitate, ellipsoid, 1.5–2 mm, short beaked. |
stipitate, obovoid, 4–7.5 mm. |
Seeds | 1, yellow or pale brown, ellipsoid, 0.9–1 mm, smooth, glossy. |
1, yellow-brown, mitten-shaped, 1.8–2.1 mm, rugose. |
2n | = 16, 28, 32. |
= 16. |
Trifolium dubium |
Trifolium virginicum |
|
Phenology | Flowering May–Oct. | Flowering May–Jun. |
Habitat | Disturbed ground, fields. | Shale barren slopes. |
Elevation | 0–2300 m. (0–7500 ft.) | 400–1200 m. (1300–3900 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]
|
MD; PA; VA; WV |
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 virginicum is an endemic species of shale barrens in the Appalachian Mountains, from Bedford, Franklin, and Fulton counties in Pennsylvania, southward through eastern West Virginia and western Maryland, to northwestern Virginia. Genetic similarity is high among populations of Trifolium virginicum, and gene flow appears to be low (T. M. Linscott 1994). (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) | Small: Mem. Torrey Bot. Club 4: 112, plate 75. (1894) |
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