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showy Indian clover, two-fork clover

Siskiyou clover

Habit Herbs annual, 45–65 cm, canescent. Herbs perennial, 20–50 cm, glabrous; rhizomes elongate, slender, roots tuberous.
Stems

erect, branched from base and distally, or unbranched.

erect, sparsely branched.

Leaves

palmate;

stipules ovate-oblong, 0.5–1.8 cm, margins entire, toothed, or irregularly lobed, apex acuminate;

petiole 0.5–10 cm;

petiolules to 1 mm;

leaflets 3, blades broadly obovate or elliptic, 1.7–3.3 × 1.1–2 cm, base cuneate, veins fine, margins entire or denticulate, apex rounded, obtuse, or retuse, surfaces pilose, abaxial less so.

palmate;

stipules lanceolate, 0.8–1.5 cm, margins entire or slightly lacerate, apex acuminate;

petiole 1.6–2.4 cm;

petiolules 0.5 mm;

leaflets 3, blades obovate, oblanceolate, or elliptic, 0.8–3 × 0.5–0.7 cm, base cuneate, veins fine or thickened distally, margins finely serrulate, apex acute, mucronate, or retuse, surfaces glabrous.

Inflorescences

terminal or axillary, 30–50-flowered, bluntly conic, ellipsoid, globose, or subglobose, 1.5–3 × 1.5–2.5 cm;

involucres absent.

usually terminal, sometimes axillary, 30–50-flowered, subglobose, 1.2–1.8 × 1.5–2 cm;

involucres shallowly bowl-shaped, 18–22 mm, deeply incised, lobes slender, irregular or bifurcate.

Peduncles

5–15 cm.

2.8–3.4 cm.

Pedicels

absent;

bracteoles cuplike, to 0.5 mm.

straight, 0.5–0.8 mm;

bracteoles linear, 1–2 mm.

Flowers

13–16 mm;

calyx tubular, 9–12 mm, pubescent, veins 20–30, tube 3 mm, lobes nearly equal, appearing rigidly erect, linear-setaceous, plumose, sinuses acute, orifice open;

corolla white to pink with purple tips, 12–16 mm, banner ovate-oblong, 12–15 × 4 mm, apex broadly rounded, emarginate.

10–13 mm;

calyx tubular, 0.5–0.6 mm, glabrous, veins 10, tube 2 mm, lobes ± equal, 3–4 mm, orifice open;

corolla white to purple, 9–12 mm, banner oblong, 7–12 × 2–3 mm, apex retuse.

Legumes

obovoid, 4 mm.

oblong, 2–4 mm.

Seeds

1, dark brown, ellipsoid, 2–3 mm, smooth.

2–4, brown, subglobose or mitten-shaped, 1.5 mm, smooth.

Trifolium amoenum

Trifolium siskiyouense

Phenology Flowering Apr–May. Flowering Jun–Jul.
Habitat Grassy slopes, swales, clay soils. Wet meadows, grassy hillsides.
Elevation 0–100 m. (0–300 ft.) 1000–1500 m. (3300–4900 ft.)
Distribution
from FNA
CA
[WildflowerSearch map]
[BONAP county map]
from FNA
CA; OR
[BONAP county map]
Discussion

Trifolium amoenum was considered extinct (J. P. Smith Jr. 1984) but was rediscovered in 1993 (P. G. Connors 1994). Specimens of T. amoenum are known from Marin, Napa, San Mateo, Solano, and Sonoma counties; it appears to be extant in only single populations in each of Marin and Solano counties. Allozyme studies of the two known populations revealed fixed genetic differences between them (E. E. Knapp and Connors 1999).

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

Trifolium siskiyouense is known from Shasta and Siskiyou counties, California, and Douglas, Jackson, and Josephine counties, Oregon. It is difficult to distinguish from T. wormskioldii without underground parts showing the tubers, but can be separated from the latter by deeply cut involucral segments, long-lobed, slender calyces, and the combination of long wing petals and short keel petals (J. M. Gillett 1980).

(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. 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. 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. 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. 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. wormskioldii var. siskiyouense
Name authority Greene: Fl. Francisc., 27. (1891) J. M. Gillett: Canad. J. Bot. 58: 1441. (1980)
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