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

strawberry clover

Habit Herbs annual, 20–40 cm, glabrous or sparsely hairy. Herbs perennial, 5–50 cm, pubescent or glabrous.
Stems

erect to prostrate, branched from base.

prostrate or creeping, branched, rooting at nodes.

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 linear or lanceolate, dilated proximally, 1.3–2 cm, margins entire, apex subulate or acuminate;

petiole 1–9 cm;

petiolules 1 mm;

leaflets 3, blades ovate, obovate, or elliptic, 0.5–3 × 0.3–1.5 cm, base cuneate, veins prominent, thickened, curved, margins spinulose-denticulate, apex obtuse, often retuse, surfaces hairy abaxially, glabrous adaxially.

Inflorescences

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

involucres absent.

axillary, erect or ascending, 10–30-flowered, globose, 0.8–2 × 0.8–2 cm;

involucres cup-shaped, composed of bracteoles, bracteoles lanceolate-oblong, 3–6 mm, distinct or connate proximally.

Peduncles

1–1.5 cm.

3–17 cm.

Pedicels

reflexed, 0.2–0.5 mm;

bracteoles a fringe of red setae.

straight, to 0.5 mm;

bracteoles linear or lanceolate, 2–3 mm, acuminate or 2-fid.

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.

6–8 mm;

calyx tubular, inflated in fruit, markedly asymmetric-bilabiate, 2.5–7 mm, usually pilose to woolly, sometimes glabrescent, veins 5–10, connected by reticulating lateral veins, tube 2–7 mm, lobes unequal, abaxial equal to or longer than tube, straight, adaxial spreading in fruit, shorter than tube, very unequal in fruit, orifice open;

corolla white to pink, 5–8 mm, banner oblong-lancelate, 5–8 × 2 mm, apex emarginate to crenulate.

Legumes

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

ovoid, 2.5–3 mm, long-beaked.

Seeds

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

1 or 2, tan or brown-spotted, globose-reniform, 1–1.4 mm, smooth, dull.

2n

= 16, 28, 32.

= 16.

Trifolium dubium

Trifolium fragiferum

Phenology Flowering May–Oct. Flowering Apr–Nov.
Habitat Disturbed ground, fields. Meadows, fields, roadsides, sandy and saline soils.
Elevation 0–2300 m. (0–7500 ft.) 0–2000 m. (0–6600 ft.)
Distribution
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]
from FNA
AZ; CA; CO; GA; IA; ID; IL; KS; MA; MN; MT; ND; NE; NJ; NM; NV; NY; OH; OR; PA; SD; UT; WA; WI; WY; BC; ON; c Europe; s Europe; w Asia [Introduced in North America; introduced also in s South America, Pacific Islands (New Zealand), Australia]
[WildflowerSearch map]
[BONAP county map]
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 fragiferum is cultivated for pastures and in mixtures with grass for hay and silage and, to a lesser extent, as groundcover in orchards and vineyards and as a green manure cover crop (L. St. John et al. 2010). It appears to have been introduced accidentally in the 1870s and as a crop around 1900 (E. A. Hollowell 1939).

(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. 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
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. 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 Amoria bonannii, T. bonannii, T. fragiferum subsp. bonannii
Name authority Sibthorp: Fl. Oxon., 231. (1794) Linnaeus: Sp. Pl. 2: 772. (1753)
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