Lathyrus sylvestris

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Name: Lathyrus sylvestris L.

Family: Fabaceae (the Pea family)

Common Names: Flat-Pea, Flat Peavine, Narrow-leaf Everlasting-Pea, Perennial Pea (2,3,7,8).

Etymology: Lathyrus is derived from the Greek word “lathyros”, which means legume, or bean (10). “Sylvestris” means “of woods or forest” (11).

Lathyrus_sylvestris_e9c9399aBotanical synonyms: Lathyrus variegatus Gilib (7).

Quick Notable Features:
¬ leaves bear just two linear-lanceolate leaflets (5)
¬ fruits are long, flat pods, tapered at both ends (6)
¬ climbs using branched tendrils borne at the tip of the leaves
¬ flower petals are pinkish purple (6)

Plant Height: L. sylvestris can grow to be 1.5 to 2.15 m with support, and 46 to 76 cm without a support (1).

Subspecies/varieties recognized (20, 21):
Lathyrus sylvestris v. cirrhosus (Ser.) P. Fourn
L. sylvestris v. intermedius Kožuharov
L. sylvestris subsp. latifolius (L.) Ponert
L. sylvestris subsp. heterophyllus (L.) Bonnier & Layens
L. sylvestris subsp. pyrenaicus (Jordan) O. Bolòs & Vigo

Most Likely Confused with: In flower it might be confused with the genera Securigera, Vicia, and Viola, as well as other species of Lathyrus, especially Lathyrus latifolius (everlasting pea)(5).

Habitat Preference: The species is found in fields, areas of human activity such as roadsides, and sometimes in wooded areas (2). 

Geographic Distribution in Michigan: The species is scattered throughout Michigan, but is more abundant in the northern region. It is found in the northern counties of the Lower Peninsula, but also in Isabella, Huron, Ingham, and Monroe counties in the south.  It is also in the following counties of the Upper Peninsula: Keweena, Gogebic, and Alger (2).

Known Elevational Distribution: Lathyrus sylvestris is found up to 2120m in Utah (13).

Complete Geographic Distribution: Indigenous to and widely distributed in Europe (southwestern France), Asia, and northern Africa (7).  Introduced throughout the United States, it is found in the northwest, northeast, and southeast regions.  L. sylvestris also can be spotted in southern areas of Canada: British Columbia, Ontario, New Brunswick, and Quebec (4).

lathyrus sylvestris-boslathyrus-04453Vegetative Plant Description: L. sylvestris is a perennial vine with woody roots. Each alternate leaf is pinnately compound with a single pair of leaflets (5-15cm long in native range of Russia, although reported as shorter from North America: 1-7.6cm) and characteristic longitudinal veins. The coriaceous stipules are semi-sagittate, pointed at the tip, and about half as wide as the winged stem (< 2cm long).  Stipule lobes are half as wide as the stem or narrower. The leaflets are narrowly lanceolate, coriaceous, with conspicuous veins. The petiole is winged. The seedlings first develop taproots, but later develop rhizomes (1,2,4,6,15).

LATSYL_SCG7Climbing Mechanism: The species climbs using branched tendrils borne at tip of leaf rachis (6).

Flower Description: The inflorescence of L. sylvestris is a raceme (an unbranched inflorescence where flowering is from base to apex) with 3-10 flowers per inflorescence. The calyx is bell-shaped and each sepal is triangular-lanceolate shaped.  The teeth of the calyx taper toward the apex (6). The non-fragrant flowers are 1-2 cm long, in which the uppermost petal is the shortest, plus two lateral wings, and a pair of fused petals forming the keel. The flower petals are purple or pink.  Lathyrus has ten stamens: nine of which bear fused filaments, forming a tube-like structure while the tenth stamen is separate.  The tube of stamens surrounds the glabrous ovary.  The fruit (ovary) bears the seeds (fertilized ovules), and develops into a classic legume bearing a finely toothed dorsal suture (1,2,18).

Flowering Time: In the United States, L. sylvestris flowers in early summer and fruits throughout the summer (3).  In Russia the flowers appear from June to August, and the fruits follow from August until September (6).

LATSYL_SCG4Pollinator: Bumblebees, carpenter bees, and bruchid beetles have been cited as pollinators.  Most pollen transfer is within a local range (4).

Fruit Type and Description: The mature fruits of L. sylvestris are yellowish legumes.  They are long and laterally narrow (flat) (about 6cm long and 1cm wide).  Both ends of the pod are tapered (6).  Both ovaries and fruits are glabrous (without hairs) (2).

Seed Description: The seeds are globose (6).

Dispersal Syndrome: Fruits mature in the fall as dehiscent pods and the seeds are dispersed ballistically as the fruits dehisce violently, spilling the seeds onto the ground.  Dispersal thus occurs over a short range (4). The seeds can then roll away to establish themselves nearby (4, 15, 16, 17).

Distinguished by: L. sylvestris has smaller flowers, stipules, and fruits, with longer and wider leaves than L. latifolius (Everlasting Pea) (5).  Lathyrus is different from Vicia because Vicia always has more than two leaflets, whereas some species of Lathyrus have only two, like L. sylvestris.  A more technical character is that Vicia has a longer strip of hairs at the top of the style, right below the stigma (2).  Viola has 2 upper petals and unfused petals whereas Lathyrus only has one upper petal and two fused lower petals (2). The leaves of Viola are normally not lanceolate, and the stems are not winged (19).  Coronilla spp. bear 10-12 leaflets per leaf while Lathyrus sylvestris only bears two, although species of both genera can bear pink flowers.

Other members of the family in Michigan (number species): Amorpha (2), Amphicarpaea (1), Anthyllis (1), Apios (1), Astragalus (3), Baptisia (4), Caragana (1), Cercis (1), Chamaecrista (2), Cladrasis (1), Colutea (1), Crotalaria (1), Cytisus (1), Dalea (1), Desmodium (12), Genista (1), Gleditsia (1), Glycine (1), Gymnocladus (1), Hedysarum (1), Kummerowia (1), Lathyrus (9), Lespedeza (13), Lotus (1), Lupinus (2), Melilotus (2), Mimosa (1), Orbexilum (1), Phaseolus (2), Pisum (1), Pueraria (1), Robinia (3), Securigera (1), Senna (1), Strophostyles (1), Tephrosia (1), Trifolium (9), Vicia (8), Vigna (1), Wisteria (1), (2,14)

Ethnobotanical Uses: L. sylvestris produces chemicals that are toxic to humans and to animals.  It is the most lethal species in the genus Lathyrus, and causes damage to the central nervous system.  The toxin is primarily in the seeds of the plant, but the foliage also produces symptoms.  Farm animals such as sheep and horses sometimes eat the plants and become very ill.  The disease is called “Lathyrism” (8).

FABALathyrussylvestrisMAPPhylogenetic Information: The Fabaceae belongs to the order Fabales, which is closely related to Fagales, Cucurbitales, and Rosales within the angiosperm Eurosids I. Within Fabaceae, L. sylvestris belongs to the subfamily, Faboideae (also known as Papilionoideae). Members of this subfamily are characterized by the papilionaceous flowers. L. sylvestris is included in the tribe Fabeae (7,12).

Interesting Quotation or Other Interesting Factoid not inserted above:  Members of the Fabaceae family often have root nodules that allow for nitrogen fixing bacteria, and this family is “the third largest family of angiosperms” (12).  This may be no coincidence!
“Clones consist of a series of ramets connected by an extensive system of rhizomes. Strong subterranean stems initiated by primary ramets produce either secondary ramets or tufts of shoots without roots” (9). Thus, it seems that what may appear to be many different individuals is just one large genetically identical clone.

Literature and websites used:

  1. Fernald, M.L. 1950. Gray’s Manual of Botany, Eighth Edition. American Book Company, New York, USA
  2. Voss, E.G. 1985. Michigan Flora Part II: Dicots. Ann Arbor, Michigan, USA: Cranbrook Institute of Science.
  3. USDA, NRCS. 2008. The PLANTS Database, Version 3.1, National Plant Data Center, Baton Rouge, LA 70874-4490 USA.  September 29, 2010
  4. Hossaert-McKey, M., M. Valero, D. Magda, M. Jarry, J. Cuguen, & P. Verne 1996. The evolving genetic history of a population of Lathyrus sylvestris: evidence from temporal and spatial genetic structure. Evolution 50(5):1808-1821.
  5. Robocker, W.C. & H.D. Kerr 1964. Characteristics and herbicidal control of flat pea. Weeds: Vol. 12(1):40-42.
  6. Smekalova, T.N. Interactive Agriculture Ecological Atlas of Russia and Neighboring Countries: Economic Plants and their Diseases, Pests and Weeds 2003 – 2009 October 6, 2010
  7. USDA, ARS, National Genetic Resources Program. Germplasm Resources Information Network – (GRIN) [Online Database]. National Germplasm Resources Laboratory, Beltsville, Maryland. October 13, 2010
  8. Lewis, H.B., R.S. Fajans, M.B. Esterer, C.W. Shen, & M. Oliphant 1948. The nutritive values of some legumes, Lathyrism in the rat. The sweet pea (Lathyrus odoratus), Lathyrus sativus, Lathyrus cicera, and some other species of Lathyrus. The Journal of Nutrition 36 (5): 537-559.
  9. Magda, D., F.R. Warembourg, & V. Labeyrie 1988. Physiological integration among ramets of Lathyrus sylvestris L. Oecologia 77(2): 255-260.
  10. Brown, R.W. 1956. Composition of Scientific Words. Washington, D.C., USA: Smithsonian Institution Press.
  11. Bailey, H.L. 1963. How Plants Get Their Names. New York, NY: Dover Publications, Inc.
  12. Judd, W.S., C.S. Campbell, E.A. Kellogg, & P.F. Stevens. 1999. Plant Systematics: A Phylogenetic Approach.  Sunderland, Massachusetts: Sinauer Associates, Inc.
  13. Shultz, L.M., R.D. Ramsey, W. Lindquist, & C. Garrard. 2010. Utah State University, Logan, UT:
  14. USDA Natural Resources Conservation Service Plant Database.
  15. Hilty, J. 2002-2006. Weedy Wildflowers of Illinois. Last modified: 03-26-07,
  16. Hossaert, M. & M. Valero 1988. Effect of ovule position in the pod on patterns of seed formation in two species of Lathyrus (Leguminosae: Paplinoideae). American Journal of Botany 75(11):1714-1731.
  17. Godt, M.J.W. & J.L. Hamrick 1991. Genetic variation in Lathyrus latifolius (Leguminosae). American Journal of Botany 78(9):1163-1171.
  18. C.R. Bell, A.E. Radford, & H.E. Ahles.1968. Manual of the Vascular Flora of the Carolinas. Chapel Hill, NC: University of North Carolina Press.
  19. Holmgren, N.H. 1998. Illustrated Companion to Gleason and Cronquist’s Manual: Illustrations of the Vascular Plants of Northeastern United States and Adjacent Canada. Bronx, N.Y.: New York Botanical Garden.
  20. The International Plant Names Index (2008). Published on the Internet [accessed 10 December 2010].
  21. Missouri Botanical Garden 10 Dec 2010 <>.

Image Credits (all used with permission):
1) Flower image courtesy of Gianluca Nicolella from
2) Image of leaves from Katholieke Universiteit Leuven and Prof. Paul Busselen, from email:
3) Image of tendrils courtesy of Steve C. Garske at, University of Wisconsin, Robert W. Freckmann Herbarium
4) Fruit image courtesy of Steve C. Garske at, University of Wisconsin, Robert W. Freckmann Herbarium
5) Species distribution map, derived from the Michigan Flora Online.

Primary Authors: Erin Regan, with editing by John Bradtke and Robyn J. Burnham

© Robyn J. Burnham, University of Michigan

For additional information on Michigan Plant Diversity web pages please contact Robyn J. Burnham via email: rburnham“at”