Coast Silk Tassel (Garrya elliptica)


Shifting our focus far from the shores of San Francisco Bay, let’s turn our attention to the scrub-covered coastal hillsides. Hidden among the chaparral, scrub, and oak woodland, blending in with all the other sclerophyllous evergreen species, is a large leathery shrub or small tree called coast silk tassel (Garrya elliptica). With its relatively nondescript form and leaf characteristics, it is likely to escape notice. That is, of course, until it blooms. From afar, its unusual pendulous non-showy flower clusters might remind you of oak branches draped with the lichen California Spanish moss (Ramalina menziesii), making it a very attractive ornamental shrub for your native garden.

Although it resembles some strange oak relative, coast silk tassel is a member of the silk tassel family (Garryaceae) and not the oak family (Fagaceae). In fact, evolutionarily, the two groups are quite distant. On the one hand, the oaks belong to the Sub-class Hammamelidae (Order Fagales), a relatively small group of trees and shrubs made up of 11 families, 46 genera and nearly 1,400 species. This is a mere 0.56 percent of the estimated 250,000 flowering plant species in the Division Anthophyta (Heywood 1985). On the other hand, the Garryaceae belongs to the Sub-class Rosidae (Order Cornales), a tremendously large and diverse group of plants of every size and shape, including vines, annual herbs, shrubs, and trees. The Rosidae includes some 89 families, nearly 3,300 genera, and more than 59,000 species, comprising nearly a quarter of all flowering plant species.

However, despite its robust lineage, the Garryaceae is not well represented, consisting of only a single genus of evergreen shrubs with about 18 species. It is restricted entirely to southwestern North America, northern Central America, and the West Indies. Characteristics of the family include dioecious individuals (male and female flowers borne on separate plants), with opposite leaves that are simple and leathery with short petioles. The flowers lack petals and are borne on pendulous catkin-like clusters. Fruits are one- or two-seeded berries. If you’re inclined to hold any belief that his arrangement of families represents an evolutionary hierarchy, Munz (1968) placed the Garryaceae between the dogwood family (Cornaceae) and the madder family (Rubiaceae).

In California, the sole genus, Garrya, is represented by six species, with a total of nine species occurring in western North America (USDA online database). They range from sea level near the coast to the foothills of the Sierra Nevada to the mountains of the eastern Mojave Desert to the Oregon border. With the exception of Garrya elliptica, California’s garryas mostly form shrubs less than ten feet tall.

Also known by the monikers silk tassel bush, wavyleaf silk tassel, quinine bush, and just plain garrya, Garrya elliptica is a shrub or small tree growing as tall as 25 feet, but specimens half that height are usual. Young twigs are densely hairy (villous). The elliptic to oval leaves are two to four inches long, dark green and subglabrous above and felty-woolly on the undersides, the individual hairs being curly or wavy. The leaf margins are generally quite wavy (undulate). Both the male and female inflorescences are pendant, three to six inches long, forming January through March. The fruits are small globose berries covered in white tomentum (fuzz), becoming glabrous (hairless) with age. For those of you who shy away from the seemingly sub-atomic floral traits that are often necessary to “key” out species (like nutlet scars of Plagiobothrys), shake your head in confusion by such obscure traits as axile ovary placentation, or find it unethical to have to sacrifice an entire specimen just to know what used to be there before you pulled it up (like bulb coat patterns in Allium), you’ll be pleased to learn that it is the easily visible characteristics of the leaves and the leaf hairs that distinguish the species of Garrya. Isn’t that refreshing?

Coast silk tassel occurs on dry slopes mostly below 2,000 feet in elevation. It is associated with chaparral, coastal scrub, and mixed evergreen forests of the outer Coast Ranges from Ventura County northward to Oregon. In San Francisco, coast silk tassel was recorded from brushy slopes of Sunset Heights (Brandegee 1891), and in thickets along the bay shore from Fort Point inward (as reported in Howell, et al. 1957). Within the limits of San Francisco County, it is still present in Glen Canyon and the vicinity of Lake Merced. On nearby San Bruno Mountain, coast silk tassel is present as an occasional inhabitant of lower Colma Canyon, Bitter Cherry Ridge, lower Devil’s Arroyo, and other slopes and ravines (McClintock, et al. 1990). Several attempts have been made to reintroduce coast silk tassel at the Presidio. Seeds have been collected from San Pedro Valley Park but germination rates have been very poor. So far, attempts to grow the species at Mountain Lake have not met with much success, with a single individual surviving (remember, they’re dioecious, so it takes two to tango). However, plants grown from cuttings are looking promising at Tennessee Hollow and the Park Service is planning to attempt to establish it at Fort Point.

None of the California garryas is listed as rare or endangered under the federal or state endangered species acts, or has been assigned any status as a rare species by the CNPS. As such, impacts to it receive no protection or review under the California Environmental Quality Act (CEQA). In our local chapter area, CNPS has designated it as being locally significant due to its restricted occurrence and perceived threats to its continued existence here.

As I mentioned, it is an easy plant to overlook, as your eyes scan the brushy slopes. But starting in January, you won’t need to stand directly next to one to know what you’re looking at. So on your rainy day strolls, keep coast silk tassel in mind. I’m quite sure you’ll think to yourself, “Hey, that’d look great in my yard.” Just be sure to buy one at a nursery, and not dig up a seedling in the wild… we need them all.