Drypark Pea, Pinewoods Pea: Lathyrus bijugatus (Synonym: Lathyrus bijugatus var. sandbergii) - Tendrils lacking, represented by a single, nonprehensile bristle.
Brown's Pea, Few-flowered Pea: Lathyrus brownii (Synonyms: Lathyrus lanszwertii var. brownii, Lathyrus pauciflorus ssp. brownii, Lathyrus schaffneri) - Corolla blue or red. Tendrils of upper leaves prehensile, coiling at the tip and longer than 6 mm long. The largest leaflets are oblanceolate-obovate in outline, measuring 1.5-2.5 cm long (2-3 times longer than wide).
Beach Pea, Maritime Peavine, Pinewoods Peavine: Lathyrus japonicus var. maritimus (Synonyms: Lathyrus japonicus ssp. maritimus, Lathyrus japonicus var. glaber, Lathyrus maritimus, Lathyrus maritimus var. glaber, Pisum maritimum, Pisum maritimum var. glabrum) - A coastal species, there is a voucher speciman from Walla Walla County, southeastern Washington. Could this be a misidentified speciman?
Thick-leaved Pea, Nevada Pea: Lathyrus lanszwertii -
a. Desert Pea, Desert Peavine, Nevada Pea, Nevada Peavine, Thick-leaved Pea: Lathyrus lanszwertii var. aridus (Synonym: Lathyrus lanszwertii ssp. aridus) - Tendrils of upper leaves not prehensile, instead straight or slightly recurved at the tip, not more than 6 mm long. Stems erect, without support of tendrils. Leaflets of larger leaves linealr-elliptic in outline, 4-9 cm long and 2-5 mm wide (6-25 times longer than wide). Petals purplish. Brushy foothills and open pine forest from 1050-1800 meters in elevation from the eastern base of the Cascade Mts. in Washington and Oregonsouth to northern California and east to western Idaho.
b. Lanzwert's Peavine, Nevada Pea, Thick-leaved Pea, Thick-leaved Peavine: Lathyrus lanszwertii var. lanszwertii (Synonym: Lathyrus lanszwertii ssp. lanszwertii) - Tendrils of upper leaves prehensile, coiling at the tip and longer than 6 mm long. The largest leaflets are elliptic to linear in outline, measuring 2.5-7 cm long (at least 3 tims longer than wide). Found east of the Cascade Mts. from central Washington south through Oregon to California and east to central Idaho and Utah.
Everlasting Pea, Everlasting-pea, Perennial Pea: Lathyrus latifolius (Synonyms: Lathyrus latifolius var. splendens) - Corolla white to red. Prehensile tendrils present. leaves with 2 leaflets, each measuring longer than 4 cm long. Stems strongly winged.
Nevada Pea, Sierra Pea, Cusick's Pea: Lathyrus nevadensis -
a. Cusick's Peavine, Sierra Pea: Lathyrus nevadensis var. cusickii (Synonyms: Lathyrus cusickii, Lathyrus nevadensis ssp. cusickii) - White corolla. Tendrils lacking, represented by a single, nonprehensile bristle. Plants rhizomatous. Leaflets not heavily veined.
b. Nevada Pea, Sierra Pea, Sierran Peavine: Lathyrus nevadensis var. nevadensis (Synonyms: Lathyrus lanceolatus, Lathyrus nevadensis ssp. lanceolatus, Lathyrus nevadensis ssp. lanceolatus var. nuttallii, Lathyrus nevadensis ssp. lanceolatus var. pilosellus, Lathyrus nevadensis ssp. nevadensis, Lathyrus nevadensis var. nuttallii, Lathyrus nevadensis var. pilosellus, Lathyrus nuttallii) - Tendrils lacking, represented by a single, nonprehensile bristle.
c. Nevada Pea, Sierra Pea: Lathyrus nevadensis var. puniceus (Synonym: Lathyrus nevadensis ssp. lanceolatus var. puniceus) - Corolla pinkish-tinged. Tendrils lacking, represented by a single, nonprehensile bristle. Wenatchee Mts.
Cream Pea, Woodland Pea: Lathyrus ochroleucus - White corolla.
Few-flowered Pea: Lathyrus pauciflorus - Corolla blue or red.
a. Fewflower Pea, Few-flowered Pea, Few-flowered Peavine, Few-flowered Vetchling, Utah Sweet Pea: Lathyrus pauciflorus var. pauciflorus (Synonyms: Lathyrus pauciflorus ssp. pauciflorus, Lathyrus pauciflorus ssp. tenuior) - Corolla blue or red.
b. Few-flowered Pea, Few-flowered Vetchling, Utah Pea, Utah Peavine, Utah Sweet Pea: Lathyrus pauciflorus var. utahensis (Synonym: Lathyrus pauciflorus ssp. utahensis) - Corolla blue or red.
Leafy Pea, Leafy Peavine: Lathyrus polyphyllus -
Bushy Pea, Bushy Peavine, Rigid Pea, Stiff Pea, Stiff Vetchling: Lathyrus rigidus - White corolla. Tendrils lacking, represented by a single, nonprehensile bristle. Non-rhizomatous, plants many-stemmed arising from a thick taproot. Leaflets heavily veined.
Flat Pea, Flat Peavine, Narrow-leaf Pea: Lathyrus sylvestris -
Earth-nut Pea, Tuberous Sweetpea: Lathyrus tuberosus - Leaves with 2 leaflets, each measuring 2-4 cm long. Stems not winged. Introduced. Found in Okanogan County, WA?