By Millie Basden
It’s a tiny plant packed with biological intrigue: it’s a geophyte, heterostylous, hysteranthus, bears a cyme, and is named after a giant of the botanical world. The plant is coast jepsonia (Jepsonia parryi) and while fairly common in Mission Trails Regional Park, it is often overlooked. John K. Small, an American botanist, named the genus after Willis Linn Jepson in 1896 when Small proposed moving two plants previously in the genus Saxafraga to his newly created genus Jepsonia.
Willis Jepson lived from 1867 to 1946. He served as professor of botany at UC Berkeley and his 1925 book “A Manual of the Flowering Plants of California” was the forerunner of “The Jepson Manual,” the weighty tome still used by botanists today. The book that bears his name is big and heavy, but the plants that bear his name are small and dainty.
A geophyte is an “earth-loving” plant that has a reproductive structure underground, an enlarged stem that may take the form of a corm or a bulb. Plants in several families are geophytes. Coast jepsonia is in the family Saxifragaceae, which got its name (meaning “rock crusher”) from the plants’ favored rocky habitats.
The flowers of coast jepsonia have styles that are different lengths, a condition known as “heterostyly.” This can make pollination difficult and may be an adaption that no longer serves a purpose. The pollinators for plants in the genus Jepsonia are syrphid flies (also called hover flies) and halictid bees (also called sweat bees); small pollinators for small flowers.
In fall, a tiny white flower with five petals and dark veins on the floral cup opens at the end of a bare stem just a few inches tall. Coast jepsonia’s initial flower is usually accompanied by two or three other flowers on lateral stems, forming an inflorescence called a “cyme.” Weeks later, triggered by fall rains, the flowers are followed by one or two dark green roundish leaves that hug the ground. When a plant flowers before leaves appear, it earns the designation of being “hysteranthus.” Sometimes a coast jepsonia plant will have flowers and leaves present at the same time, but usually not. In a very dry year, there may be no leaves at all. During our hot dry summers, the flowers and leaves disappear, and the plants are dormant. Like other geophytes, you can expect that coast jepsonia will reappear during the next wet season from its underground parts.
You can find coast jepsonia in the park in many places. Look on north-facing slopes (including road cuts and trail edges) or areas with clay soils that are shaded by other plants or rocks. Keep in mind the typical life cycle — you are most likely to find flowers during the months of October and November; leaves without flowers are likely beginning in December. By May, you are not likely to find any above-ground evidence of the plant.
The diminutive stature and short above-ground lifespan of coast jepsonia belie its significance as a plant that has much to teach us and that bears the name of a giant from the world of botany.
— Millie Basden is a trial guide at Mission Trails Regional Park.