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

bowl clover, cup clover

Habit Herbs annual, 10–60 cm, glabrous. Herbs annual, 5–50 cm, glabrous.
Stems

erect, branched.

erect, 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, 0.6–1.2 cm, margins entire, toothed, or lacerate, apex acute or aristate;

petiole 1–10 cm;

petiolules to 0.5 mm;

leaflets 3, blades obovate, elliptic, or oblanceolate, 0.5–2.5 × 0.3–1.5 cm, base cuneate, veins prominent, green, margins finely toothed, apex rounded, blunt, or retuse, surfaces glabrous.

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, 1–35-flowered, subglobose or ovoid, 0.5–1.8 × 0.5–2 cm;

involucres broadly bowl-shaped, 4–22 mm, shallowly incised, lobes 3–15, toothed, broad, acute.

Peduncles

2–15 cm.

1–8 cm.

Pedicels

erect, 0.5 mm;

bracteoles absent.

straight, 0.1–0.2 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.

7–15 mm;

calyx campanulate, inflated in fruit, 6–13 mm, glabrous, veins 13–20, tube 3–7 mm, lobes unequal, strongly oblique, broadly triangular, apex setaceous, adaxial unbranched, abaxial and lateral conspicuously 2- or 3-fid, segments glabrous, sometimes flattened, orifice open;

corolla usually creamy white or rose to pink, sometimes whitish with pinkish tips, 6–13 mm, banner obovate or elliptic, proximally inflated in fruit, distally narrowed into twisted tip, 6–13 × 3–6 mm, apex rounded to broadly acute.

Legumes

ellipsoid, 3 mm.

ellipsoid, 2.5–3 mm.

Seeds

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

1 or 2, yellow-brown, ovoid, 0.4–0.6 mm, smooth.

2n

= 16.

= 16.

Trifolium willdenovii

Trifolium cyathiferum

Phenology Flowering Mar–Jul. Flowering Apr–Oct.
Habitat Roadsides, meadows, lawns, hill­sides, stream margins, open oak chaparral. Wet meadows, roadsides, fields.
Elevation 0–2500 m. (0–8200 ft.) 0–2700 m. (0–8900 ft.)
Distribution
from FNA
AZ; CA; ID; OR; WA; BC; Mexico (Baja California)
[WildflowerSearch map]
from FNA
AK; CA; ID; MT; NV; OR; WA; BC; YT [Introduced in Asia (China, Japan)]
[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.)

Trifolium cyathiferum may be of hybrid origin; phylogenetic studies indicate it has the same trnL intron sequence as T. buckwestiorum, T. polyodon, and T. variegatum and nrDNA and combined analyses place it in a clade with other species (T. barbigerum, T. fucatum, T. jokerstii, and T. physanthum Hooker & Arnott) that have inflated fruiting corollas (N. W. Ellison et al. 2006).

The single record of Trifolium cyathiferum labeled as from Utah is likely mislabeled (S. L. Welsh et al. 2008). Populations in Yukon may be introductions.

(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. 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. 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. willdenovii, T. wormskioldii
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) Lindley: Bot. Reg. 13: sub plate 1070. (1827)
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