Common Pacific Pea

Common Pacific Pea © KKorbholz

Hillside Pea
Lathyrus vestitus var. vestitus
NATIVE

Description (Jepson, PlantID.net)

    • Eudicotyledon
      • Eudicots are a major lineage of flowering plants; see family for general characteristics
    • Pea / Legume Family (Fabaceae)
    • Climbing, herbaceous perennial, with tendrils
    • Stems are 3-sided (triangulate in cross-section), often sharply-edged or flanged
    • Leaves
      • Compound (divided into leaflets) and pinnate (arranged along a common axis, like a feather)
      • 8-12 grey-green leaflets end in one or more coiling tendrils, which anchor the plant
      • Prominent arrow-shaped stipules (a pair of leaf-like structures at the base of the leaf stalk), with wavy edges
    • Flowers
      • Inflorescence (flower arrangement) of up to 15 flowers in a raceme (unbranched flower cluster with short, equal stalks)
      • Characteristic Pea / Legume family flower is bilaterally-symmetric with a banner, wings, and keel
        • Banner, bent upward at about 90o; is light violet, lavender, or whitish, with purple lines (nectar guides)
        • Wings are pale violet to white
        • Keel, partly hidden by the wings, is white
      • Ovary superior (above the attachment of other flower parts)
    • Fruit is a pea pod, a kind of legume (a single-chambered seed pod that opens along 2 seams)
    • Height to 28 in.
    Pea Flower

    Distribution

      • Native to California
        • Grows in coastal sage scrub, chaparral, and oak woodlands 55-64% of plants occur on serpentine (ultramafic) soils; see Serpentine affinity rankings (Calfora per Safford and Miller 2020)
        • See Calflora for statewide observations of this plant
      • Outside California, grows from Oregon south to the Mexican border
      • Grows at elevations to 4,900 ft.

      Uses (Picking or removing any natural material from public land is illegal)

        • Frequented by insects (primarily large bees) and hummingbirds for nectar
        • Host plant for the larval stage of silvery blue (Glaucopsyche lygdamus) and northern cloudywing (Thorybes pylades) butterflies
        • Native people had several uses for common Pacific pea
          • Ate raw seeds and greens
          • Made a decoction of roots for use as a general medicinal remedy
        • CAUTION – The fruits of many members of this genus contain a potent neurotoxin, which if not properly treated, can cause paralysis (Nature Collective 2020); best to avoid eating any wild peas
        Pea Pod © DSchiel

        Name Derivation

          • Laythrus (LA-thi-rus) – from the Greek lathyros, “pea”
          • vestitus (ves-TIE-tus) – from the Latin for “covered” or “clothed,” referring to hairs

          Notes

            • Like almost all members of its family, common pacific pea fixes nitrogen; see Pea / Legume family for more details
            • Each flower part plays a role in insect pollination (Broich 1983)
              • Banner petals have red lines, called nectar or floral guides, directing insects to pollen and/or nectar; some floral guides are invisible to the human eye unless viewed with ultraviolet light
              • Wing petals are the “landing platforms” for pollinators
              • Anthers (pollen-producing part of the stamen/male structure) and stigma (pollen-receiving structure of the female flower) are hidden in the keel
              • To get access, pollinators must be heavy enough to depress the wing-keel, pushing the stigma between the keel petals
              • Pollen grains in the keel are “brushed” out by the stigma’s hairs as the stigma moves forward to make contact with the insect
            • Flowers fade to yellow-brown and remain on the stem
            • Genus includes the garden sweet pea (L. odoratus), native to southern Europe
            • Edgewood’s common Pacific pea is classified as a variety
              • Subspecies rank is used to recognize geographic distinctiveness, whereas variety rank is appropriate for variants seen throughout the geographic range of the species; in practice, these two ranks are not distinct

            ID Tips

              • May be confused with the several vetch (Vicia) species at Edgewood, including native American vetch (Vicia americana ssp. americana) and non-native spring vetch (Vicia sativa ssp. sativa)
              Common Pacific Pea2American VetchSpring Vetch
              Leaves
                  New Leavesrolled like a cigarflatclosed like a book
                  Stipules
                  (pair of leaf-like structures at     base of leaf stalk)
              large (≤ 0.7 in.) and wavy-edgedsmall (~0.1 in.), star-like, with 3 teeth on lower halfsmall and toothed, with a dark-red dot
              Flowers
                  Clusterup to 15 flowers on a long raceme33-5 flowers on a long raceme31-2 flowers at junction with stem 
                  Colorpastels; pale lavender to purple, fading to yellow-browndark purple banner; wings and keel pale purple to whitedark pink-purple
                  Banner Anglebent up at 90°bent up at less than 90°bent up at less than 90°
                  Stigma1
                  (pollen-receiving structure of     female flower)
              hairs on one sidehairs all aroundhairs all around
              1 Peek, but don’t pick or tear apart to see the stigma
              2 You can associate the pea, like its homophone, with bathroom items, i.e. toothbrush (stigma) and toilet paper (rolled leaves)
              3 Raceme – an unbranched flower cluster with short, equal stalks
              Common Pacific Pea (L), American Vetch (M), Spring Vetch (R), Stigma Hairs (illustration)
              © DSchiel (L,R), KKorbholz (M), JMason (illustration)

              At Edgewood

                • Found in woodlands
                  • See iNaturalist for observations of this plant
                    • Note observations are for Lathyrus vestitus
                • Flowers March – May

                See General References

                Specific References

                  Broich, S.L. 1983. A systematic study of Lathyrus Vestitus Nutt. ex T. & G. (Fabaceae) and allied species of the Pacific Coast. Dissertation. Oregon State University, Corvallis, Oregon.

                    Mason, J. 2004. Common Pacific Pea and American Vetch stigma illustrations, adapted. In T. Corelli, Flowering Plants of Edgewood Natural Preserve, 2nd. ed. Monocot Press, Half Moon Bay, California. (c) CC BY NC 3.0.

                      Mitchell. M. 2017. Fabaceae: Pea Family — Vicia (Vetch). Monterey County Wildflowers, Trees, & Ferns – A Photographic Guide.

                        Nature Collective. 2020. Chaparral Sweet Pea.

                          Prigge, B.A. and Gibson, A.C. 2013. Lathyrus vestitus var. vestitus. A Naturalist’s Flora of the Santa Monica Mountains and Simi Hills, California. Web version, hosted at Wildflowers of the Santa Monica Mountains National Recreation Area. National Park Service. US Department of Interior.

                            Safford, H.D. and Miller, J.E.D. 2020. An Updated Database of Serpentine Endemism in the California Flora. [manuscript accepted by] Madrono, California Botanical Society, Northridge, California.