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

aspen peavine, lanszwert's pea, lanszwert's vetchling, Nevada pea, Nevada peavine, Nevada sweet pea, pinewood peavine, Rocky Mountain sweetpea, thick-leaf pea, thick-leaf peavine

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

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

angled, erect, sprawling, or climbing, basally branched 0–4 times, 1–8 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.

(0.5–)1–8 cm;

tendrils mucronate to well developed;

stipules linear to lanceolate, 5–25 × 1–6 mm, much smaller than leaflets;

leaflets 2–10, scattered, blades lanceolate or linear, 20–70 × 2–20 mm, surfaces glabrous or sparsely pubescent.

Inflorescences

2–7-flowered, 3–15 cm.

2–6-flowered, 2–10 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.

7–15 mm;

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

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

ovary glabrous.

Legumes

25–60 × 4–8 mm.

25–45 × 6–10 mm.

2n

= 14.

Lathyrus palustris

Lathyrus lanszwertii

Phenology Flowering Apr–Aug.
Habitat Coastal and inland wetlands.
Elevation 0–1800 m. (0–5900 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 USDA
w North America
[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.)

Varieties 5 (5 in the flora).

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

Key
1. Stems (2–)3–8 dm, usually climbing, sometimes sprawling or erect; tendrils well developed, usually branched.
→ 2
2. Leaflets 8–10; corollas blue-purple; California northward to Washington, eastward to Colorado and Wyoming.
var. lanszwertii
2. Leaflets 6–8; corollas white; w Colorado, c Utah, Wyoming.
var. pallescens
1. Stems 1–3(–4) dm, usually erect (sometimes var. bijugatus sprawling or climbing); tendrils reduced to simple bristles less than 1 cm.
→ 3
3. Leaflets 2–4; e Washington, adjacent Idaho, Montana, British Columbia.
var. bijugatus
3. Leaflets 4–8; California northward to sc Washington and eastward to New Mexico, Colorado, and Wyoming.
→ 4
4. Flowers 7–10 mm; California, Nevada, Oregon, Washington.
var. aridus
4. Flowers 10–15 mm; Arizona, Colorado, New Mexico, Utah, Wyoming.
var. leucanthus
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. eucosmus, L. glandulosus, L. graminifolius, L. grimesii, L. hirsutus, L. hitchcockianus, L. holochlorus, L. japonicus, L. jepsonii, L. laetivirens, 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
Subordinate taxa
L. lanszwertii var. aridus, L. lanszwertii var. bijugatus, L. lanszwertii var. lanszwertii, L. lanszwertii var. leucanthus, L. lanszwertii var. pallescens
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
Name authority Linnaeus: Sp. Pl. 2: 733. (1753) Kellogg: Proc. Calif. Acad. Sci. 2: 150, fig. 44. (1863)
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