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gesse des marais, marsh pea, marsh peavine, marsh vetchling

bush vetchling, seemly pea

Habit Herbs perennial, from rhizome, glabrous or pubescent. Herbs perennial, from rhizome, glabrous or puberulent.
Stems

narrowly to broadly winged, sprawling or climbing, basally branched 0–4 times, 2–10 dm.

angled, erect, basally branched 0–2 times, 2–5 dm.

Leaves

1–6 cm;

tendrils well developed;

stipules ovate-lanceolate to linear, 5–25 × 1–10 mm, much smaller than leaflets;

leaflets 4–8, paired, blades lanceolate to linear, 15–75 × 2–20 mm, surfaces glabrous, glabrate, or pubescent.

2–4 cm;

tendrils simple or branched, sometimes prehensile;

stipules linear, 5–15 × 1–2 mm, much smaller than leaflets;

leaflets 6 or 8, scattered, blades ovate to lanceolate, 15–45 × 4–10 mm, surfaces glabrous throughout or puberulent abaxially.

Inflorescences

2–7-flowered, 3–15 cm.

2–4-flowered, 7–12 cm.

Flowers

10–15 mm;

calyx lobes unequal, lateral lobes deltate, shorter than tube;

corolla blue-purple, banner erect, blade equal to claw, wings equal to keel;

ovary glandular-pubescent.

18–20 mm;

calyx lobes unequal, lateral lobes deltate, shorter than tube;

corolla blue-purple, banner erect, blade longer than claw, wings equal to keel (held above keel);

ovary glabrous.

Legumes

25–60 × 4–8 mm.

40–50 × 8–10 mm, short-stipitate.

2n

= 14.

= 14.

Lathyrus palustris

Lathyrus eucosmus

Phenology Flowering Apr–Aug. Flowering Apr–Jun.
Habitat Coastal and inland wetlands. Dry soils in washes, pinyon-juniper woodlands, oak-brush, ponderosa pine forests, open prairies, grasslands.
Elevation 0–1800 m. (0–5900 ft.) 1200–2500 m. (3900–8200 ft.)
Distribution
from FNA
AK; AL; AR; CA; CO; CT; DC; DE; IA; IL; IN; KY; MA; MD; ME; MI; MN; MO; NC; ND; NE; NH; NJ; NY; OH; OR; PA; RI; SD; TN; VA; VT; WA; WI; WV; BC; MB; NB; NL; NS; NU; ON; PE; QC; SK; SPM
[WildflowerSearch map]
[BONAP county map]
from FNA
AZ; CO; NM; TX; UT; WY; Mexico (Coahuila)
[WildflowerSearch map]
[BONAP county map]
Discussion

Morphological variation within Lathyrus palustris is extensive. Although the most distinctive forms (see synonyms) have been accorded formal nomenclatural recognition (M. L. Fernald 1911; C. L. Hitchcock 1952), intergradation among these mostly sympatric ecotypes is widespread (D. Isely 1998). In Nunavut, it is known only from Akimiski Island in James Bay.

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

Lathyrus eucosmus is known from the northern two-thirds of Arizona northward to southeastern Utah, and eastward in southeastern Wyoming, Colorado, New Mexico, and Texas to the edge of the Great Plains.

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

Source FNA vol. 11. FNA vol. 11.
Parent taxa Fabaceae > subfam. Faboideae > Lathyrus Fabaceae > subfam. Faboideae > Lathyrus
Sibling taxa
L. angulatus, L. aphaca, L. biflorus, L. brachycalyx, L. brownii, L. cicera, L. decaphyllus, L. delnorticus, L. eucosmus, L. glandulosus, L. graminifolius, L. grimesii, L. hirsutus, L. hitchcockianus, L. holochlorus, L. japonicus, L. jepsonii, L. laetivirens, L. lanszwertii, L. latifolius, L. littoralis, L. nevadensis, L. nissolia, L. ochroleucus, L. odoratus, L. pauciflorus, L. polyphyllus, L. pratensis, L. pusillus, L. rigidus, L. sphaericus, L. splendens, L. sulphureus, L. sylvestris, L. tingitanus, L. torreyi, L. tracyi, L. tuberosus, L. venosus, L. vestitus
L. angulatus, L. aphaca, L. biflorus, L. brachycalyx, L. brownii, L. cicera, L. decaphyllus, L. delnorticus, L. glandulosus, L. graminifolius, L. grimesii, L. hirsutus, L. hitchcockianus, L. holochlorus, L. japonicus, L. jepsonii, L. laetivirens, L. lanszwertii, L. latifolius, L. littoralis, L. nevadensis, L. nissolia, L. ochroleucus, L. odoratus, L. palustris, L. pauciflorus, L. polyphyllus, L. pratensis, L. pusillus, L. rigidus, L. sphaericus, L. splendens, L. sulphureus, L. sylvestris, L. tingitanus, L. torreyi, L. tracyi, L. tuberosus, L. venosus, L. vestitus
Synonyms L. myrtifolius, L. palustris var. linearifolius, L. palustris var. macranthus, L. palustris var. myrtifolius, L. palustris subsp. pilosus, L. palustris var. pilosus, L. palustris var. retusus L. brachycalyx subsp. eucosmus, L. brachycalyx var. eucosmus
Name authority Linnaeus: Sp. Pl. 2: 733. (1753) Butters & H. St. John: Rhodora 19: 160. (1917)
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