Lathyrus palustris (Marsh vetchling)

Lathyrus palustris L.

Marsh vetchling, marsh pea

Kingdom	Plantae	Plants, but not fungi, lichens, or algae
Subkingdom	Tracheobionta	Vascular plants—plants with a “circulatory system” for delivering water and nutrients
Division	Magnoliophyta	Flowering plants, also known as angiosperms
Class	Magnoliopsida	Dicotyledons—plants with two initial seed leaves
Subclass	Rosidae	Roses, legumes, proteas, dogwoods, hydrangeas, mistletoes, euphorbias, grapes, many more
Order	Fabales	Legumes (pea and bean families)
Family	Fabaceae	Legume family (peas and beans)
Genus	Lathyrus	From Greek lathyros, an old name for “pea”
Species	palustris	“Growing in marshes”

About plant names...

Marsh pea is native to Europe, Asia, and North America. It has an affinity for wet freshwater areas.

Identification: A vinelike plant 12-48" (30-121 cm) long, with stems that are often “winged.” That is, viewed in cross-section, the central circle of the stem has two flat projections emerging from opposite sides. Each projection is ¹/₁₆-⅛" (2-5 mm) wide. Some stems and even some entire plants lack these wings. Stems may also be angular or grooved. (Confused yet?) Branch tips have tendrils that latch onto other plants. Leaves are pinnate—composed of opposing pairs of leaflets. Leaflets often form the shape of a V, and may be asymmetrical. They are lance-shaped, about 1-2½" (2.5-6.3 cm) long and up to ½" (1.3 cm) wide, green on top, pale green below. Flowers are purple and white, about ¾" (1.9 cm) in size. They appear in clusters of 2-8, from June to August. Seedpods are 1-2½" (2.5-6.3 cm) long × ¼" (6.3 mm) around, similar to those of related garden peas, but smaller.

Online References:

Lathyrus palustris at Illinois Wildflowers

Lathyrus palustris at Minnesota Wildflowers

Lathyrus palustris on

Lathyrus palustris on Ontario Wildflowers

Lathyrus palustris on eFloras

Lathyrus palustris from the Jepson Manual

References:

Newcomb, Lawrence, Morrison, Gordon (Illus.), Newcomb’s Wildflower Guide, Little, Brown and Company, 1977, p. 114

8/8/2010 · Jeff Smith Trail, Beaver Brook Association Conservation Lands, Rte. 130, Hollis, New Hampshire
≈ 7 × 9" (16 × 23 cm)

8/8/2010 · Jeff Smith Trail, Beaver Brook Association Conservation Lands, Rte. 130, Hollis, New Hampshire
≈ 7 × 9" (16 × 22 cm)

7/5/2015 · Jeff Smith Trail, Beaver Brook Conservation Area, Hollis, New Hampshire
≈ 6 × 5" (15 × 13 cm)

7/5/2015 · Jeff Smith Trail, Beaver Brook Conservation Area, Hollis, New Hampshire
≈ 5 × 8" (13 × 19 cm)

6/20/2016 · Wildlife Pond Trail, Beaver Broo, Hollis, New Hampshire

8/8/2010 · Jeff Smith Trail, Beaver Brook Association Conservation Lands, Rte. 130, Hollis, New Hampshire
≈ 3 × 2½" (7.7 × 6.7 cm)

6/20/2016 · Wildlife Pond Trail, Beaver Broo, Hollis, New Hampshire

8/2/2010 · Beaver Brook Association Conservation Lands, Rte. 130, Hollis, New Hampshire
≈ 4½ × 3" (11 × 7.9 cm)

7/2/2017 · Wildlife Pond, Beaver Brook Conservation Area, Hollis, New Hampshire
≈ 2½ × 3" (6.5 × 7.4 cm)

Lathyrus myrtifolius Muhl. ex Willd.

Lathyrus palustris L. var. linearifolius Ser.

Lathyrus palustris L. var. myrtifolius (Muhl. ex Willd.) A. Gray

Lathyrus palustris L. var. macranthus (T.G. White) Fernald

Lathyrus palustris L. var. meridionalis Butters & H. St. John

Lathyrus palustris L. var. pilosus (Cham.) Ledeb.

Lathyrus palustris L. ssp. pilosus (Cham.) Hultén

Lathyrus palustris L. var. retusus Fernald & H. St. John

Orobus myrtifolius Alef.

Lathyrus palustris description by Thomas H. Kent, last updated 25 May 2020.

8/8/2010 · Jeff Smith Trail, Beaver Brook Association Conservation Lands, Rte. 130, Hollis, New Hampshire
≈ 3 × 5" (8.4 × 12 cm)

7/5/2015 · Jeff Smith Trail, Beaver Brook Conservation Area, Hollis, New Hampshire
≈ 5 × 6" (12 × 14 cm)

7/5/2015 · Jeff Smith Trail, Beaver Brook Conservation Area, Hollis, New Hampshire
≈ 3 × 3" (8 × 7.6 cm)

6/20/2016 · Wildlife Pond Trail, Beaver Broo, Hollis, New Hampshire

8/8/2010 · Jeff Smith Trail, Beaver Brook Association Conservation Lands, Rte. 130, Hollis, New Hampshire
≈ 3 × 3" (8.5 × 7.5 cm)

6/20/2016 · Wildlife Pond Trail, Beaver Broo, Hollis, New Hampshire

7/17/2012 · Beaver Brook Association Conservation Lands, Rte. 130, Wildlife Pond Trail, Hollis, New Hampshire
≈ 2½ × 2½" (7.2 × 6.6 cm)

7/5/2015 · Jeff Smith Trail, Beaver Brook Conservation Area, Hollis, New Hampshire
≈ 6 × 4" (14 × 10 cm)

7/5/2015 · Jeff Smith Trail, Beaver Brook Conservation Area, Hollis, New Hampshire
≈ 4½ × 4" (11 × 10 cm)

Winged stem. (Flowers in this image are not marsh vetchling.) · 7/17/2012 · Beaver Brook Association Conservation Lands, Rte. 130, Wildlife Pond Trail, Hollis, New Hampshire
≈ 7 × 4½" (17 × 11 cm)

7/17/2012 · Beaver Brook Association Conservation Lands, Rte. 130, Wildlife Pond Trail, Hollis, New Hampshire
≈ 6 × 4" (15 × 10 cm)

7/5/2015 · Jeff Smith Trail, Beaver Brook Conservation Area, Hollis, New Hampshire
≈ 5 × 7" (13 × 16 cm)

8/2/2010 · Beaver Brook Association Conservation Lands, Rte. 130, Hollis, New Hampshire
≈ 8 × 5" (19 × 13 cm)

7/2/2017 · Wildlife Pond, Beaver Brook Conservation Area, Hollis, New Hampshire
≈ 2 × 2½" (5.9 × 6.2 cm)

Range:

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