Perennial Sweet Pea – Lathyrus latifolius – naturalized along the shores of Pitt Lake, near Maple Ridge, B.C., August 2011. Image: HFN
Perennial Herbaceous Vine. Zone 3. Fabaceae, formerly Leguminosae. Originally native to Southern Europe, now sometimes seen naturalized in disturbed-soil areas as a garden escapee throughout Europe, Great Britain, and parts of North America, including coastal British Columbia. Lathyrus is from the Greek lathyros, pea; latifolius from the Latin latus + folium, wide + leaf.
Clump former to 18 inches wide; sprawls or climbs 3 to 6 feet tall by twining tendrils in the leaf axils. Fine in average soil and moisture; prefers full sun. Established plants are reasonably drought tolerant, but thrives best with summer moisture and fertile soil.
This pretty climber/sprawler is rather rare in Cariboo-Chilcotin gardens, but I have seen it thriving often enough here and there in Zone 3 and 4 Williams Lake and Quesnel area plantings to be able to confidently recommend its hardiness and adaptability.
The plant forms a vigorous clump of rapidly elongating stems lined with paired, blue-green leaflets. Bloom stalks and twining tendrils emerge from the leaf axils as the stems lengthen. Clusters of very showy, sweet pea-like flowers bloom for a long period June through August, and are followed by typical large, flat pea-pods filled with big round seeds. (These are not considered edible, by the way, and occasionally are referenced as “poisonous”, though I have not seen any mention of actual incidents of poisoning.)
Sadly, the “sweet” reference is merely to its similar appearance to the highly fragrant annual sweet pea, Lathyrus odoratus, as Perennial Sweet Pea is not noticeably fragrant.
Vines reach 3 to 6 feet long – tallest where it can climb, and where grown in moist, fertile soil – and either sprawl along the ground or twine their way up whatever support they can find. Very nice grown on a bank where it can cascade, or on a sturdy trellis or garden obelisk arrangement. Vines are completely herbaceous, and die back to the ground in the winter, to re-sprout in spring. Sometimes late to emerge, so keep an eye out for it when digging about in the spring garden.
A very long-lived plant, which should be sited where it can remain as it does not transplant well. It may self sow, but though definitely a “survivor” where established, it is not aggressive and is not considered an invasive plant in our climate, though it is occasionally seen as a naturalized garden escapee in disturbed soil areas along coastal British Columbian roadsides where it has joined other exotics such as butterfly bush (Buddleja sp.), touch-me-not (Impatiens sp.), and the ubiquitous Himalayan Blackberries.
Lathyrus latifolius naturalized along the shoreline roadway at Pitt Lake, near Maple Ridge, B.C. August, 2011. Image: HFN
Lathyrus latifolius has been grown as a prized garden flower for centuries throughout Europe and the British Isles, and in North American colonial plantings, and the pink strain appears in the 1801 species inventory of Thomas Jefferson’s famed Monticello garden.
This plant often shows up on old herb garden lists, but no medicinal uses are recorded. Apparently the foliage was occasionally used as a pot herb, and the seeds cooked and consumed for their high protein content, but present-day consumption is definitely NOT recommended, as the seeds of some of the species in the Lathyrus genus do contain potentially harmful amino aids. Best to enjoy it for its beauty alone, as most of our gardening predecessors did.
Many species of bees and butterflies visit the flowers in search of nectar, as do occasional questing hummingbirds, but the floral structure is designed for pollination by bumblebees, as they alone are strong enough to part the keel petals which enclose the reproductive parts of the blooms.
Three old-fashioned named strains are still available; all are very lovely. ‘RED PEARL’ – rich carmine pink. ‘ROSE PEARL’ aka ‘PINK BEAUTY’ – pale pink flushed darker at petal edges. ‘WHITE PEARL’ – pristine snow white.
Lathyrus latifolius – typical of ‘Red Pearl’ colour strain – Maple Ridge, August 2011. Image: HFN
Hill Farm Nursery 