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arrow-leaf clover

thimble clover, Valparaiso clover

Habit Herbs annual, 15–70 cm, glabrous. Herbs annual, 6–35 cm, villous or glabrous.
Stems

erect or ascending, branched.

erect or ascending, branched.

Leaves

palmate;

stipules linear-lanceolate, 1–3.5 cm, margins entire, apex subulate or setaceous;

petiole 0.5–10 cm;

petiolules 1 mm;

leaflet 3, blades obovate to oblong, elliptic or lanceolate, 0.5–4 × 0.5–1.5 cm, base cuneate, veins prominent, thickened, margins spinulose-denticulate, apex apiculate, surfaces glabrous.

palmate;

stipules obliquely ovate, 0.4–1.2 cm, margins entire, toothed, or lacerate, apex acuminate;

petiole 1–8 cm;

petiolules 0.5 mm;

leaflets 3, blades obovate or obcordate, 0.4–1.4 × 0.3–1.2 cm, base cuneate, veins fine, thickened distally, margins serrate, apex rounded or emarginate, surfaces villous or glabrous.

Inflorescences

terminal or axillary, 50–100+-flowered, globose, ovoid, or oblong, 3–6 × 2–3.5 cm;

involucres absent.

axillary or terminal, 10–17-flowered, subglobose, 0.8–1.7 × 0.5–1.5 cm;

involucres cup-shaped, 0.5–1.5 cm, glabrous or sparsely hairy, lobes 8–12, ovate, conspicuously sharply toothed.

Peduncles

1–12 cm.

1.5–7.4 cm.

Pedicels

absent;

bracteoles lanceolate, 6–7 mm, acuminate.

absent;

bracteoles absent.

Flowers

12–16 mm;

calyx urceolate, not bilabiate, inflated in fruit, 6–10 mm, glabrous, veins 20–36, connected by transverse veins in fruit, tube 3–5 mm, lobes reflexed, subequal, subulate, as long as tube, orifice constricted;

corolla white becoming pink, 12–15 mm, banner ovate, broadly clawed, striate, 12–15 × 2–4 mm, apex acute-acuminate.

6–7 mm;

calyx tubular-campanulate, 3–4 mm, glabrous, veins 10, tube 2.5–3.5 mm, lobes ± equal, triangular, not or minutely aristate, conspicuously toothed, margins membranous, orifice open;

corolla pale pink or white, 6–9 mm, banner oblong, 6–9 × 2–3 mm, apex narrowly rounded or emarginate-mucronate.

Legumes

ellipsoid, 2.5–2.5 mm, shorter than calyx.

ovoid, 2–3 mm.

Seeds

2 or 3, brown, ovoid, 1–1.5 mm, roughened.

1 or 2, greenish, sometimes mottled, oblong, 1.5–2 mm, smooth.

2n

= 16.

= 16.

Trifolium vesiculosum

Trifolium microdon

Phenology Flowering Apr–Jul. Flowering Apr–Jul.
Habitat Fields, roadsides, forest openings. Meadows, roadsides, dry slopes, fields, open oak or pine forests.
Elevation 0–1000 m. (0–3300 ft.) 0–1500 m. (0–4900 ft.)
Distribution
from FNA
AL; AR; CA; FL; GA; LA; MA; MO; MS; OK; OR; SC; TX; VA; WA; s Europe; e Europe; w Asia [Introduced in North America]
[WildflowerSearch map]
[BONAP county map]
from FNA
CA; ID; OR; WA; BC; Mexico (Baja California); South America (Chile)
[WildflowerSearch map]
[BONAP county map]
Discussion

Trifolium vesiculosum was first introduced into cultivation in the United States in 1963 and is grown in southern and western states (J. D. Miller and H. D. Wells 1985).

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

Trifolium microdon is one of several clovers that have an apparently natural disjunct distribution between the western coast of South America (Chile) and western North America. Others include T. depauperatum var. depauperatum and T. macraei.

In herbarium specimens of Trifolium microdon, the folded involucre hides, or nearly hides, the calyces, whereas in herbarium specimens of similar T. microcephalum, the calyces are still visible.

(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. 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. 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. microdon var. pilosum
Name authority Savi: Fl. Pis. 2: 165. (1798) — (as vessiculosum) Hooker & Arnott: Bot. Misc. 3: 180. (1833)
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