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field clover, hop clover, hop trefoil, low hop-clover, pinnate hop clover

Douglas' clover

Habit Herbs annual, 5–40 cm, slightly villous or glabrous. Herbs perennial, 20–75 cm, glabrous or slightly pilose.
Stems

erect to ascending, branched.

erect, unbranched or sparsely branched.

Leaves

pinnate;

stipules ovate-lanceolate, 0.5–0.8 cm, margins entire, glandular, apex acuminate;

petiole 0.3–2 cm;

lateral leaflet petiolules 0.5–0.6 mm, terminal leaflet stalk 3–5 mm;

leaflets 3, blades rhombic to obovate, 0.4–1.5 × 0.4–0.8 cm, base cuneate, lateral veins prominent, ± parallel, ascending, margins denticulate distally, apex truncate or retuse, surfaces strigose adaxially.

palmate;

stipules lanceolate to ovate, 1.5–6.5 cm, margins setose-serrulate or entire, apex acuminate;

petiole 1.5–15 cm;

petiolules 1 mm;

leaflets 3, blades elliptic-oblanceolate to linear-elliptic, 3–9.5 × 0.5–1.6 cm, base cuneate, lateral veins prominent, recurved, dichotomously forked near margin, margins setose-denticulate to serrate, apex rounded or acute, surfaces glaucous, glabrous, sometimes sparsely pubescent abaxially.

Inflorescences

axillary, 30–60-flowered, globose or broadly ovoid, 0.8–1.5 × 0.7–1 cm;

involucres absent.

terminal or axillary, 30–50+-flowered, umbellate, globose to ovoid, 1.5–5 × 2–3.5 cm;

involucres absent.

Peduncles

1.5–3.5 cm.

3–12 cm.

Pedicels

reflexed, 0.7–1.2 mm;

bracteoles a fringe of red setae.

erect or slightly reflexed, to 0.2 mm;

bracteoles minute.

Flowers

4.3–5 mm;

calyx campanulate, strongly bilabiate, 1.3–1.5 mm, glabrous, veins 5, tube 0.3–0.6 mm, lobes unequal, adaxial deltate, very short, lateral and abaxial linear-subulate, each tipped with 1 or 2 stiff hairs, orifice open;

corolla yellow becoming brown, 3.5–6 mm, ribbed, banner persistent, obovate, enveloping other petals, boat-shaped, 4.3–5 × 2.8–3.2 mm, apex broad, acute.

14–16 mm;

calyx campanulate, 6–9 mm, pilose, veins 15–20, tube 1.5–3 mm, lobes unequal, narrow, triangular or subulate, abaxial lobe straight, lateral and adaxial tortuous, recurved inwards around corolla, orifice open;

corolla magenta, 12–16 mm, banner oblong, 12–16 × 4–6 mm, apex flared, acute or obtuse;

ovaries glabrous or pubescent distally.

Legumes

stipitate, oblong, 2–2.5 mm.

ovoid, 3–4.5 mm.

Seeds

1 or 2, yellow, ellipsoid, 1–1.5 mm, smooth, lustrous.

1 or 2, tan to brown, ovoid, 1–1.5 mm, slightly roughened.

2n

= 14.

= 16.

Trifolium campestre

Trifolium douglasii

Phenology Flowering Jun–Aug. Flowering Jun–Jul.
Habitat Roadsides, fields. Moist meadows, rich soils in prairies, stream bottoms and banks, openings in pine forests.
Elevation 0–1700 m. (0–5600 ft.) 600–1500 m. (2000–4900 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; NY; OH; OK; OR; PA; RI; SC; TN; TX; VA; VT; WA; WI; WV; WY; BC; NB; NF; NS; ON; PE; QC; SPM; Europe; w Asia; n Africa [Introduced in North America; introduced also in South America, e Asia (China), s Africa, Pacific Islands (Hawaii, New Zealand), Australia]
[WildflowerSearch map]
[BONAP county map]
from FNA
ID; OR; WA
[WildflowerSearch map]
[BONAP county map]
Discussion

Trifolium filiforme Linnaeus and T. procumbens Linnaeus are rejected names that were used historically for T. campestre (J. E. Dandy 1958; N. J. Turland et al. 1996).

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

Trifolium douglasii is rare throughout its range and has been impacted by agricultural practices (P. Camp et al. 2011).

(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. 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
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. 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 Chrysaspis campestris T. altissimum
Name authority Schreber in G. F. Hoffmann: Deutschl. Fl. 4: 16, plate 253. (1804) House: Bot. Gaz. 41: 335. (1906)
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