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sand clover, thimble clover, tomcat clover, Willdenow's clover

carpet clover, mountain carpet clover

Habit Herbs annual, 10–60 cm, glabrous. Herbs perennial, 3–22 cm, glabrous or hairy, often mat-forming.
Stems

erect, branched.

decumbent to ascending, much-branched.

Leaves

palmate;

stipules lanceolate or ovate, 1–2 cm, margins dentate or lacerate, apex acuminate;

petiole 1–8 cm;

petiolules 0.5 mm;

leaflets 3, blades linear, lanceolate, or elliptic, 1–5 × 0.2–1.5 cm, base cuneate, veins fine, margins serrate, apex acute, blunt, or retuse, surfaces glabrous.

palmate;

stipules ovate to lanceolate, 0.3–1.2 cm, margins entire, serrate, or slightly lacerate, apex acute to acuminate;

petiole 1–4.5 cm;

petiolules 0.1–0.5 mm;

leaflets 3, blades obovate, oblanceolate, or elliptic, 0.3–2 × 0.2–0.5 cm, base cuneate, veins prominent, margins ± dentate, serrate, or setose, apex acute, rounded, or retuse, surfaces glabrous or slightly villous.

Inflorescences

axillary or terminal, 10–50-flowered, globose or ovoid, 1–3.5 × 1–3 cm;

involucres flattened or bowl-shaped, 3–9 mm, when folded, not hiding flowers except proximally, incised 1/4–1/3 their length.

axillary or terminal, 1–9-flowered, solitary or subglobose, 1–1.6 × 0.3–1.2 cm;

involucres campanulate, 2–5 mm, incised nearly to base, lobes 2–8, lanceolate.

Peduncles

2–15 cm.

0.5–2 cm.

Pedicels

erect, 0.5 mm;

bracteoles absent.

erect, 1 mm;

bracteoles absent.

Flowers

12–20 mm;

calyx tubular-campanulate, slit between adaxial lobes, 6–9 mm, glabrous, veins 10–15, tube 3–7 mm, lobes unequal, triangular or subulate, usually 3-fid or shouldered below apex, orifice open;

corolla usually white with purple spot, sometimes lavender or pink or all white, 10–18 mm, banner narrowly oblong, 12–20 × 3–4 mm, apex obtuse or retuse.

10–16 mm;

calyx tubular, 2–10 mm, glabrous or pubescent, veins 10, tube 4–7 mm, lobes equal, triangular-subulate, orifice open;

corolla white, pink, or lavender, keel petals usually purple-spotted, 8–16 mm, banner oblong, 8–13 × 2–5 mm, apex emarginate.

Legumes

ellipsoid, 3 mm.

oblong, 2–4 mm.

Seeds

1 or 2, yellow, mottled, globose-ellipsoid, 1.5–2.5 mm, smooth.

1 or 2, brown, mottled, mitten-shaped, 1–2 mm, dull.

2n

= 16.

= 16.

Trifolium willdenovii

Trifolium monanthum

Phenology Flowering Mar–Jul.
Habitat Roadsides, meadows, lawns, hill­sides, stream margins, open oak chaparral.
Elevation 0–2500 m. (0–8200 ft.)
Distribution
from FNA
AZ; CA; ID; OR; WA; BC; Mexico (Baja California)
[WildflowerSearch map]
from USDA
w United States; nw Mexico
[WildflowerSearch map]
[BONAP county map]
Discussion

Trifolium willdenovii was described by M. Zohary and D. Heller (1984) as one of the most variable clover species in North America.

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

Subspecies 4 (4 in the flora).

Morphological intergradation among subspecies of Trifolium monanthum may be indicative of low genetic barriers to crossing. It might be just as plausible to divide T. mononathum into two species instead of four subspecies (J. M. Gillett 1980), with T. monanthum encompassing populations with white rhizomes, and T. multicaule encompassing populations with taproots.

Trifolium monanthum often forms dense mats.

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

Key
1. Herbs glabrous or sparsely hairy, mat-forming; stems from thin to thick woody roots, rhizomes slender, white; peduncles straight or bent upwards at steep angle distally; flowers 1–5.
→ 2
2. Inflorescences (1 or)2–4-flowered; peduncles straight; leaflet blades obovate to oblanceo­late, margins ± dentate, apex rounded or retuse.
subsp. monanthum
2. Inflorescences 1–5-flowered; peduncles bent upwards at steep angle distally; leaflet blades oblanceolate or elliptic, margins setose, apex acute.
subsp. grantianum
1. Herbs densely hairy, decumbent to ascending; stems from thickened woody taproots, rhizomes absent; peduncles bent upwards at steep angle distally; flowers 1–9.
→ 3
3. Leaflet blade apex rounded, margins dentate.
subsp. parvum
3. Leaflet blade apex acute, margins serrate or setose.
subsp. tenerum
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. 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. 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. 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
Subordinate taxa
T. monanthum subsp. grantianum, T. monanthum subsp. monanthum, T. monanthum subsp. parvum, T. monanthum subsp. tenerum
Synonyms T. involucratum, T. aciculare, T. nuttallii, T. scabrellum, T. segetum, T. tridentatum, T. tridentatum var. aciculare, T. tridentatum var. scabrellum, T. tridentatum var. segetum, T. tridentatum var. watsonii, T. trimorphum, T. watsonii
Name authority Sprengel: Syst. Veg. 3: 208. (1826) A. Gray: Proc. Amer. Acad. Arts 6: 523. (1865)
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