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burrowing clover, subclover, subterranean clover, subterranean trefoil

narrow-leaf clover, narrow-leaf crimson clover

Habit Herbs annual, 10–80 cm, glabrous or appressed-pubescent. Herbs annual, 10–30 cm, appressed-pubescent.
Stems

prostrate to ascending, branched.

erect, unbranched to sparsely branched.

Leaves

palmate;

stipules ovate, 0.5–3 cm, margins entire or slightly toothed, ciliate, apex acute to acuminate;

petiole 1–20 cm;

petiolules 1 mm;

leaflets 3, blades broadly obcordate, 0.8–2.8 × 1–3 cm, base cuneate, veins delicate, widely spaced, margins mostly entire, slightly dentate distally, apex emarginate, surfaces appressed-sericeous.

palmate;

stipules lanceolate to linear, 0.5–2.2 cm, margins entire, apex lanceolate-linear;

petiole 2–3 cm;

petiolules 1+ mm;

leaflets 3, blades linear-lanceolate, 3–5 × 0.2–0.4 cm, base cuneate, veins fine, margins entire, apex acute, surfaces hairy.

Inflorescences

axillary, elongate and reflexed, pushing into substrate after anthesis, fertile flowers 2–7, sterile flowers 0–80, globose or cylindric, 0.5–1.5 × 0.8–1.5 cm;

involucres absent.

terminal, 25–75-flowered, spicate, cylindric or conic, 3–8 × 1.5–2 cm;

involucres absent.

Peduncles

2–6.5 cm.

1–2.2 cm.

Pedicels

reflexed after anthesis, 0.2–0.4 mm;

bracteoles absent.

erect, 0.5 mm;

bracteoles absent.

Flowers

fertile ones 7–15 mm;

calyx tubular, 5–6 mm, glabrous or hairy, veins indistinct, tube 3–4 mm, lobes subequal, pubescent or glabrous, spreading, orifice open;

corolla white, pink, or pink-striped, 7–10 mm, banner ovate-elliptic, 7–10 × 1.5–2 mm, apex rounded;

sterile flowers 4–7 mm;

calyx teeth linear;

corolla absent.

10–13 mm;

calyx tubular, 8–13 mm, tuberculate with appressed, stiff hairs, veins 10, tube 3–5 mm, lobes unequal, abaxial lobes longest, subulate-setaceous, spreading stellate in fruit, orifice closed by bilabiate callosities, hairy;

corolla usually pale pink or purple, rarely white, 9–12 mm, banner ovate-elliptic, 9–12 × 2–2.5 mm, apex notched.

Legumes

subterranean, obovoid, 3–4 mm.

ovoid, leathery distally, transversely dehiscent, 2.2–2.5 mm.

Seeds

1, purplish black, ellipsoid, 2.6–3 mm, smooth, dull.

1, light brown or yellow, ovoid, 1.6–2 mm, smooth, glossy.

2n

= 16.

= 14, 16.

Trifolium subterraneum

Trifolium angustifolium

Phenology Flowering Mar–May. Flowering Mar–Apr.
Habitat Open, disturbed sandy soils. Waste places, fields, meadows.
Elevation 0–1000 m. (0–3300 ft.) 0–1000 m. (0–3300 ft.)
Distribution
from FNA
CA; GA; LA; MA; MS; NC; NJ; OR; SC; WA; BC; w Europe; w Asia; n Africa [Introduced in North America; introduced also in s South America, s Africa, Pacific Islands (Hawaii, New Zealand), Australia]
[WildflowerSearch map]
[BONAP county map]
from FNA
AL; CA; OR; SC; Europe; w Asia; n Africa; Atlantic Islands (Canary Islands) [Introduced in North America; introduced also in s South America (Chile, Uruguay), s Africa, Pacific Islands (New Zealand), Australia]
[WildflowerSearch map]
[BONAP county map]
Discussion

Trifolium subterraneum was first introduced by the USDA about 1921 as a pasture crop; it is utilized as such in the western and southern United States (W. S. McGuire 1985). Inflorescences of T. subterraneum consist of intermixed sterile and fertile flowers; after fetilization, the inflorescence is pushed underground, where the fruits develop.

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

Trifolium angustifolium is spreading rapidly in west-central California and is weedy in many regions globally (R. P. Randall 2002).

(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. 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. 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. willdenovii, T. wormskioldii
Name authority Linnaeus: Sp. Pl. 2: 767. (1753) Linnaeus: Sp. Pl. 2: 769. (1753)
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