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

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

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

angled, erect or sprawling, basally branched 0–2 times, 1.5–3 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.

1–4 cm;

tendrils bristlelike, usually less than 1 cm;

stipules linear to lanceolate, 10–30 × 1–5 mm, nearly equal to leaflets;

leaflets 8–12, often paired, blades lanceolate to linear, 10–35 × 1–5 mm, surfaces glabrous or pubescent.

Inflorescences

2–7-flowered, 3–15 cm.

2–6-flowered, 4–11 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.

16–22 mm;

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

corolla usually violet to magenta, sometimes white, banner erect, blade longer than claw, wings 4–5 mm longer than keel;

ovary glabrous.

Legumes

25–60 × 4–8 mm.

35–50 × 8–12 mm, stipitate.

2n

= 14.

Lathyrus palustris

Lathyrus decaphyllus

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
wc United States
[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 2 (2 in the flora).

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

Key
1. Herbs mostly glabrous.
var. decaphyllus
1. Herbs sparsely to densely villous.
var. incanus
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. 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. 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. decaphyllus var. decaphyllus, L. decaphyllus var. incanus
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) Pursh: Fl. Amer. Sept. 2: 471. (1813)
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