Common name: Vasey’s Coyote-thistle

Scientific name: Eryngium castrense
Family: Apiaceae (carrot)
Habitat: vernal pools
Size: plant 8 to 18 inches tall, flower 2 to 3 mm in the summer

Fun facts: Plant has two different forms: when in water the leaves are hollow to carry air to the roots; later the leaves are solid and prickly like a thistle.

Description: Member of the carrot family. The plant has a fleshy taproot like most members of this family. The flowers are tiny and purple and bloom in the early summer. They occur in pale green, prickly heads where the leaves are clustered.

This is the only green prickly plant that occurs in vernal pools.

Life cycle: Coyote-thistles are one of the two vernal pool plants that live for more than a few weeks. They are short lived perennials or biennials (live for two years). They grow from a fleshy taproot while there is water in the vernal pools. As the pools dry, their leaves become prickly. Vasey’s Coyote-thistle blooms in June.

Ecology: Vasey’s Coyote-thistle has two different leaf forms; one for when it is aquatic (growing in the water) and one for when it is terrestrial (growing on land instead of in the water). Vernal Pool Dodder (Cuscuta howelliana) often grows on Vasey’s Coyote-thistle and even puts its flowers in the flower clusters of the coyote-thistle.

Investigate: Can you find an example of both leaf forms on the same plant? Or on two different plants in the same pool?