By Ellen Dean
The Rare Plant of the Month blog highlights one of the rare plants in the CNPS Rare Plant Inventory (RPI), an invaluable resource that has helped protect approximately 2,450 rare plant taxa in California since 1974!
This month’s rare plant, Mendocino Coast paintbrush (Castilleja mendocinensis) belongs to the broomrape family (Orobanchaceae). You hear about family reunions where everyone gets together, but a reunion like that would probably be challenging for this plant family because it includes both fully parasitic plants (holoparasites) and semi-parasitic (hemiparasites) plants. (Dinner at the reunion would need a varied menu.) The parasites obtain all their nutrition from attaching to a plant host, while the hemiparasites produce carbohydrates via photosynthesis and obtain additional needed nutrients by attaching themselves to a host. Castilleja plants attach to the roots of a host via haustoria, a stem or root-like appendage. (You may remember another hemiparasite highlighted in this series: Soft salty bird’s-beak, which is also in the broomrape family.)
There are approximately 200 species in the genus Castilleja, with the majority in the western United States, and there are nearly 70 different kinds of Castilleja native to California! The genus is also native to Mexico, Central and South America, and northern Eurasia. Mendocino Coast paintbrush has fleshy, purplish leaves and produces showy red inflorescences (clusters of flowers) from April to August. However, like many other paintbrushes, the showy part of the inflorescence is actually the bracts subtending the corollas. (Let’s break down some of the plant lingo: Bracts are small, leaf-like structures that are usually beneath the flowers and a corolla refers to the petals arranged around the center of a flower.) In this case, the bracts are relatively wide, each one with a bright-red to orange-red tip. The more inconspicuous yellow tubular corollas are known to provide nectar for and be visited by several species of butterflies and moths, but paintbrushes are also known to be visited by bees and hummingbirds.
In California, this species grows right along the coast ranging from the border of Sonoma/Mendocino counties to Humboldt County and then north to Curry County, Oregon. The majority of the 52 California populations are found in Mendocino County, and only five extant populations are known from Oregon. The mostly small populations are usually found in coastal scrub, dunes, and prairie on headlands and sea bluffs at less than 160m in elevation. (Pro tip: People have observed this plant relatively recently at MacKerricher State Park.) The coastal habitat of Mendocino Coast paintbrush is thought to be highly threatened over the long-term. Dangers include coastal development, erosion, recreation, foot traffic, non-native plants, and habitat fragmentation. According to NatureServe, Mendocino Coast paintbrush is critically imperiled in Oregon and imperiled in California. In the CNPS Rare Plant Inventory, Mendocino Coast paintbrush is ranked 1B.2 (rare, threatened, or endangered in California and elsewhere). Visit the Rare Plant Inventory to learn more about Mendocino Coast paintbrush.
Ellen Dean is Associate Rare Plant Botanist at CNPS, helping complete rare plant profiles. In a previous life, she was an herbarium botanist, performing plant IDs, leading collecting field trips, training students in plant identification, curating the herbarium, and publishing taxonomic papers.
