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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

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.

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.

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.

Peduncles

1–1.5 cm.

2.5–15 cm.

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.

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.

Legumes

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

stipitate, oblong, 6–7 mm.

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.

2n

= 16, 28, 32.

Trifolium dubium

Trifolium parryi

Phenology Flowering May–Oct.
Habitat Disturbed ground, fields.
Elevation 0–2300 m. (0–7500 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 USDA
w United States
[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.)

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.)

Key
1. Inflorescences ellipsoid, 3–3.7 cm; leaflet blades thick; stipules 1.5–2 cm; peduncles thickened.
subsp. salictorum
1. Inflorescences globose or ovoid, 1.4–2.9 cm; leaflet blades thin; stipules 0.5–1 cm; peduncles slender or slightly thickened.
→ 2
2. Involucres: bracteoles relatively large, acute; inflorescences 2.1–2.9 cm; flowers 14–22 mm; Colorado, New Mexico, s Wyoming.
subsp. parryi
2. Involucres: bracteoles relatively short, obtuse; inflorescences 1.4–2.4 cm; flowers 12–17 mm; s Idaho, Montana, e Utah, n Wyoming.
subsp. montanense
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. 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. 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
Subordinate taxa
T. parryi subsp. montanense, T. parryi subsp. parryi, T. parryi subsp. salictorum
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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