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rose clover

least hop clover, lesser hop clover, lesser hop trefoil, little hop clover, shamrock, small hop-clover, suckling clover

Habit Herbs annual, 10–35 cm, densely spreading-hairy. Herbs annual, 20–40 cm, glabrous or sparsely hairy.
Stems

curved-ascending, branched.

erect to prostrate, branched from base.

Leaves

palmate;

stipules lanceolate-ovate, 0.8–1.8 cm, margins entire, apex long-setaceous;

petiole 0.5–5 cm;

petiolules 0.5 mm;

leaflets 3, blades obovate to oblong, 0.8–2.5 × 0.5–1.3 cm, base cuneate, veins prominent, closely-spaced, margins denticulate distally, apex rounded, surfaces densely spreading-hairy.

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.

Inflorescences

terminal on branches, 10–50-flowered, globose or ovoid, disarticulating in fruit, 1.5–2.5 × 1.5–2.5 cm;

involucres absent, involucrelike structures formed by enlarged stipules.

axillary or terminal, 5–20-flowered, ovoid or globose, 0.5–0.9 × 0.6 cm;

involucres absent.

Peduncles

absent.

1–1.5 cm.

Pedicels

absent;

bracteoles absent.

reflexed, 0.2–0.5 mm;

bracteoles a fringe of red setae.

Flowers

10–17 mm;

calyx campanulate, 7–11 mm, pilose, veins 20, tube 2–5 mm, lobes subequal, abaxial slightly longer, orifice hairy, open;

corolla purplish red, 10–14 mm, banner lanceolate, 10–14 × 1–2 mm, apex acute-acuminate.

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.

Legumes

ovoid, leathery distally, transversely dehiscent, 2–3 mm.

stipitate, ellipsoid, 1.5–2 mm, short beaked.

Seeds

1, tan or brown, globose-ellipsoid, 1.5–2 mm, smooth, glossy.

1, yellow or pale brown, ellipsoid, 0.9–1 mm, smooth, glossy.

2n

= 10.

= 16, 28, 32.

Trifolium hirtum

Trifolium dubium

Phenology Flowering Apr–Jun. Flowering May–Oct.
Habitat Fields, roadsides. Disturbed ground, fields.
Elevation 0–2100 m. (0–6900 ft.) 0–2300 m. (0–7500 ft.)
Distribution
from FNA
AL; CA; FL; LA; NC; OR; TN; VA; s Europe; w Asia; n Africa [Introduced in North America; introduced also in s Africa, Pacific Islands (New Zealand), Australia]
[WildflowerSearch map]
[BONAP county map]
from FNA
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]
[WildflowerSearch map]
[BONAP county map]
Discussion

Trifolium hirtum was first cultivated in California in the 1940s as a forage plant and as a nitrogen source in roadside grass plantings (R. M. Love 1985); it is now widespread in that state. It was reported for Kentucky by D. Isely (1998); no non-cultivated specimens have been seen from that state (M. A. Vincent 2001).

(Discussion copyrighted by Flora of North America; reprinted with permission.)

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.)

Source FNA vol. 11. FNA vol. 11.
Parent taxa Fabaceae > subfam. Faboideae > Trifolium Fabaceae > subfam. Faboideae > Trifolium
Sibling taxa
T. albopurpureum, T. alexandrinum, T. amoenum, T. amphianthum, T. andersonii, T. andinum, T. angustifolium, T. appendiculatum, T. arvense, T. attenuatum, T. aureum, T. barbigerum, T. barnebyi, T. beckwithii, T. bejariense, T. bifidum, T. bolanderi, T. brandegeei, T. breweri, T. buckwestiorum, T. calcaricum, T. campestre, T. carolinianum, T. cernuum, T. ciliolatum, T. columbinum, T. cyathiferum, T. dasyphyllum, T. dedeckerae, T. depauperatum, T. dichotomum, T. douglasii, T. dubium, T. echinatum, T. eriocephalum, T. fragiferum, T. friscanum, T. fucatum, T. glomeratum, T. gracilentum, T. grayi, T. gymnocarpon, T. haydenii, T. howellii, T. hybridum, T. hydrophilum, T. incarnatum, T. jokerstii, T. kentuckiense, T. kingii, T. lappaceum, T. latifolium, T. leibergii, T. lemmonii, T. longipes, T. lupinaster, T. macilentum, T. macraei, T. macrocephalum, T. medium, T. microcephalum, T. microdon, T. monanthum, T. mucronatum, T. nanum, T. nigrescens, T. obtusiflorum, T. oliganthum, T. ornithopodioides, T. owyheense, T. palmeri, T. parryi, T. pinetorum, T. piorkowskii, T. plumosum, T. polyodon, T. pratense, T. productum, T. reflexum, T. repens, T. resupinatum, T. retusum, T. rollinsii, T. siskiyouense, T. sonorense, T. stoloniferum, T. striatum, T. subterraneum, T. suffocatum, T. thompsonii, T. tomentosum, T. trichocalyx, T. variegatum, T. vesiculosum, T. virginicum, T. willdenovii, T. wormskioldii
T. albopurpureum, T. alexandrinum, T. amoenum, T. amphianthum, T. andersonii, T. andinum, T. angustifolium, T. appendiculatum, T. arvense, T. attenuatum, T. aureum, T. barbigerum, T. barnebyi, T. beckwithii, T. bejariense, T. bifidum, T. bolanderi, T. brandegeei, T. breweri, T. buckwestiorum, T. calcaricum, T. campestre, T. carolinianum, T. cernuum, T. ciliolatum, T. columbinum, T. cyathiferum, T. dasyphyllum, T. dedeckerae, T. depauperatum, T. dichotomum, T. douglasii, T. echinatum, T. eriocephalum, T. fragiferum, T. friscanum, T. fucatum, T. glomeratum, T. gracilentum, T. grayi, T. gymnocarpon, T. haydenii, T. hirtum, T. howellii, T. hybridum, T. hydrophilum, T. incarnatum, T. jokerstii, T. kentuckiense, T. kingii, T. lappaceum, T. latifolium, T. leibergii, T. lemmonii, T. longipes, T. lupinaster, T. macilentum, T. macraei, T. macrocephalum, T. medium, T. microcephalum, T. microdon, T. monanthum, T. mucronatum, T. nanum, T. nigrescens, T. obtusiflorum, T. oliganthum, T. ornithopodioides, T. owyheense, T. palmeri, T. parryi, T. pinetorum, T. piorkowskii, T. plumosum, T. polyodon, T. pratense, T. productum, T. reflexum, T. repens, T. resupinatum, T. retusum, T. rollinsii, T. siskiyouense, T. sonorense, T. stoloniferum, T. striatum, T. subterraneum, T. suffocatum, T. thompsonii, T. tomentosum, T. trichocalyx, T. variegatum, T. vesiculosum, T. virginicum, T. willdenovii, T. wormskioldii
Synonyms Chrysaspis dubia, T. minus
Name authority Allioni: Auct. Fl. Pedem., 20. (1789) Sibthorp: Fl. Oxon., 231. (1794)
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