The Three Phases of the Vernal Pool Ecosystem

The Flower Phase: Spring in the Vernal Pools

Spring is a beautiful time to visit a vernal pool grassland. As the pools dry down in March, the seeds of vernal pool plants grow in the muddy soil. Over 200 plant species can grow in vernal pools. However, over 60 of these species are endemic to vernal pools, meaning they can grow only in vernal pools and nowhere else. If not for vernal pools, they would become extinct.

The plants grow quickly along the shrinking edge of the water. Within four weeks they cover the entire bottom of each vernal pool. As the first plants bloom, their flowers can make colorful rings around the outside of the pools. During the month of April, the display of wildflowers in the pools changes from week to week. By late April, yellow, white, pink, and purple flowers carpet the pools with splashes of color.

These pink monkeyflowers grow well on bare mounds of soil heaped up by pocket gophers that tunnel under the vernal pools searching for Brodiaea bulbs.

These plants bloom late in spring. The bulbs of the Brodiaea (larger flower) are a favorite food of Botta’s Pocket Gophers. Few vernal pools host Douglas’s Beardstyle; it needs very special conditions to grow.

Vernal pools are like snowflakes in that no two are exactly alike. While each pool usually has 15 to 20 different species of wildflowers in it, the mix of species can be different in every pool. Plants select their host pools based on the growing conditions of each vernal pool. Some plants prefer shallow pools that dry quickly or the higher, drier areas within deeper pools. Other plants grow where the water is deeper and lasts longer into the spring. Most of the habits of vernal pool plants are still a mystery to scientists.

Mather Web • Lessons & Worksheets • Animal Facts • Plant Facts

©