Nature Conservancy Sign at Vernal Pool

These are the contents of one side of the sign at the vernal pool that was vandalized in early February, 1998, and removed. It was replaced sometime after that, and is still there as of 1/14/01.

Change Of Disguise For Every Season

Jan-February. 8" of rain have fallen. The water seals the clay beds under the pools. As the pools fill, fairy shrimp and aquatic plants develop. Ducks and other waterfowl relocate to this new winter home.

Early April. A carpet of green-spike brush begins to hide the pools. Endangered plants such as California orcutt grass and San Diego button celery grow beneath the water, storing energy for dry-season flowers.

May. The dry season arrives and the pool shoreline retreats. Downingia in bloom rings the pools with purple. Other flowers contributing to the pool's colorful bathtub rings include bright yellow goldfields and the tiny white popcorn flower.

September. Parched and dry, the vernal pool disguises itself as ordinary grassland, hiding its importance as wetland habitat and home to endangered species during california wet months.

Instant Shrimp

Hatches in Jan-Feb. Tiny, almost transparent, millions of these half-inch long creatures live a magical 4-week life span in the winter phase of California's vernal pools. Shrimp eggs as small and as dry as dust, lie encased in the clay pool bottoms waiting for winter rains.

Within hours of the pools filling with water, the eggs hatch. In a race against time and elements, these tiny crustaceans grow, mate and produce a new generation of eggs, which sink to the pool bottom and settle into the mud to dry in the heat of summer.

These eggs may hatch with the next spring's rain, or they may lie dormant for many years. Even in wet years, not all eggs will hatch, so that a bank of eggs from multiple years is stored in the clay, ensuring a new hatch of shrimp every wet year, no matter what happens.

Thread-Leaved Brodiaea

Looking like a small version of its cousin, lily-of-the-nile, thread-leaved brodiaea grows from a long-lived bulb which develops deep in the clay soils around the edges of vernal pools.

Brodiaea begins to grow in the early fall. Its first tender shoots emerge from the soil soon after the first rains of winter.

The single stalk bears between 3 and 30 flowers, which bloom in April or May, long after the slender leaves have withered.

The thread-leafed brodiaea doesn't come up every year. It's almost like an animal that saves its energy by hibernating in the winter. The thread-leaved brodiaea is now found in fewer than 10 places in the area. Only the Santa Rosa Plateau population is protected.

Celery Thistle

Celery thistle or lunchmeat blooms in July-August. The remarkable life of the extremely rare perennial San Diego button-celery begins in early spring. Long hollow leaves climb towards the surface of the filled vernal pools. As the pools dry, button celery begins to resemble its other common name, coyote thistle.

Occurring in only a dozen places in the region, older plants can grow to 18". It's in late July that San Diego button celery reminds us of lunchmeat, its thorny purple flowers fill the air with the scent of bologna.

Further Reading

Elias, T.E. ed. 1987. Conservation and management of rare and endangered plants, Proceedings of the California conference, California Native Plant Society, Sacramento.

Gustafson, F.S.. Ephemeral Edens, Pacific Discovery, 43:2, no. 2. California Academy of Sciences, San Francisco, Jane, S. ed. 1976.

Vernal Pools: Their Ecology And Conservation Proceedings of a symposium sponsored by the Institute of Ecology, University of California, Davis.

Smith, J.P., jr., and Kay, Bird, Inventory Of Rare And Endangered Vascular Plants Of California. California Native Plant Society, Sacramento.

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Copyright © 1998-2001 by Tom Chester.
Permission is freely granted to reproduce any or all of this page as long as credit is given to me at this source:
Comments and feedback: Tom Chester
Updated 14 January 2001.