Trifolium dubium |
Trifolium dasyphyllum |
|
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least hop clover, lesser hop clover, lesser hop trefoil, little hop clover, shamrock, small hop-clover, suckling clover |
alpine clover |
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Habit | Herbs annual, 20–40 cm, glabrous or sparsely hairy. | Herbs perennial, 5–20 cm, appressed-pubescent. |
Stems | erect to prostrate, branched from base. |
cespitose, branched, numerous short stems. |
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-linear, 1.5–2 cm, margins entire, apex acuminate; petiole 0.6–3.5 cm; petiolules to 0.5 mm; leaflets 3, blades oblong-elliptic, oblanceolate, or obovate, sometimes folded, 0.6–3.2 × 0.2–0.6 cm, base cuneate, veins obscure, margins entire, apex acute, surfaces glabrous or hairy. |
Inflorescences | axillary or terminal, 5–20-flowered, ovoid or globose, 0.5–0.9 × 0.6 cm; involucres absent. |
axillary or terminal, 5–16-flowered, globose, 1.5–3.5 × 1.2–3.3 cm; involucres formed of proximal bracteoles, bases sometimes connate. |
Peduncles | 1–1.5 cm. |
2–17 cm. |
Pedicels | reflexed, 0.2–0.5 mm; bracteoles a fringe of red setae. |
erect, 1.5–2 mm; bracteoles linear-lanceolate, scarious, 2–6 mm, or scalelike. |
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. |
12–16 mm; calyx campanulate, 6–9 mm, pubescent, veins 10, tube 2–5 mm, lobes unequal, linear-subulate, orifice open; corolla often bicolored cream and violet, sometimes all red-purple or violet, 1.2–1.6 mm, banner broadly elliptic-ovate, 11–15 × 4–5 mm, folded distally, apex rounded, apiculate; ovaries pubescent distally. |
Legumes | stipitate, ellipsoid, 1.5–2 mm, short beaked. |
oblong, 4–6 mm. |
Seeds | 1, yellow or pale brown, ellipsoid, 0.9–1 mm, smooth, glossy. |
1–3, dark brown, ovoid-reniform, 2–2.5 mm, smooth. |
2n | = 16, 28, 32. |
= 16. |
Trifolium dubium |
Trifolium dasyphyllum |
|
Phenology | Flowering May–Oct. | Flowering Jun–Aug. |
Habitat | Disturbed ground, fields. | Alpine meadows, rocky slopes. |
Elevation | 0–2300 m. (0–7500 ft.) | 2100–4100 m. (6900–13500 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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CO; MT; NM; UT; WY
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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.) |
Three subspecies of Trifolium dasyphyllum were recognized by J. M. Gillett (1965), but he commented on the overlap in diagnostic characters of the subspecies. In their monograph of Trifolium, M. Zohary and D. Heller (1984) mirrored the treatment by Gillett, and also commented on intermediacy of characters in some specimens. The subspecies were not accepted by R. D. Dorn (1988), citing extensive intergradation, or by R. C. Barneby (1989), citing variability within T. dasyphyllum that is not linked with distribution or other morphological features. Trifolium dasyphyllum is found from eastern Utah and from Santa Fe County in New Mexico northward through central Colorado to central and northwestern Wyoming and Cascade, Gallatin, and Madison counties in Montana. (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 | T. anemophilum, T. dasyphyllum subsp. anemophilum, T. dasyphyllum subsp. uintense, T. dasyphyllum var. uintense, T. lividum, T. scariosum, T. uintense |
Name authority | Sibthorp: Fl. Oxon., 231. (1794) | Torrey & A. Gray: Fl. N. Amer. 1: 315. (1838) |
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