Caley pea (Lathyrus hirsutus
) is an annual climbing vine of the Fabaceae
family. The seeds from the Lathyrus
genus are known for their toxicity, and ability to cause lathyrism if ingested in large quantities. Poisoning signs may occur within days after consumption, by eating contaminated hay, particularly Bermuda hay, or by grazing on it in pastures. Drought conditions during plant growth may increase the plant's toxicity.
appears quite similar to Hairy vetch (Vicia spp)
as it produces the same showy purple flowers and has similar-looking vines and seedpods. L. hirsutus
is one of the earlier plants to flower in the spring, with flowers emerging as soon as March in California and into May/June in other areas. It will usually remain in bloom for 1-2 months. L. hirsutus
's seedpods are flat-sided, oblong, dull brown, and taper at the tips. They are covered with long hairs that eventually become stiff in texture. The seedpods are initially green, but eventually turn brown and split open to release the seeds.
contains 3 β-N-oxalyl-L-α,β-diaminopropionic acid (β-ODAP), a potent neuroexcitatory amino acid in that induces damage to the horses' neurological system.
In 2015, 22 horses were poisoned from eating Bermuda grass hay that contained large quantities of dried L. hirsutus
that was baled in with the hay. Horses developed an incoordinated gait and mild neurogenic muscle atrophy.