Whenever I travel to the Pacific coast of Southern California I inevitably take a few moments to admire the Channel Islands. There’s just something inviting about them, something that beckons me to take a closer look, and perhaps finally plan a long-delayed visit. Perhaps its like the curiosity I have about my European relatives. While separated for many years, I suspect the Dutch Vosses would seem distantly familiar even with all the differences.
The same combination of similarity and distinction greets us when we cross the water to the Channel Islands. Although never connected to the mainland, they have received countless botanical “immigrants” for many millennia. Perhaps carried by birds, ocean currents, or Chumash travelers, many plants from the mainland took hold on the Islands. Once introduced, the plants developed unique forms (such as the low growing forms of chamise, Adenostoma fasciculatum), or perhaps survived while the continental population disappeared (such as the ironwood tree, Lyonothamnus floribundus). Of course, many of the introduced species remained indistinct from mainland populations.
As a result of this blending and changing, the Channel Islands support plant communities like no other. Fortunately, the Mediterranean climate of the Pacific Coast encompasses the California Channel Islands and many of the Pacific islands of Mexico. So many of the unique plants of these island habitats can thrive in our gardens.
Here are a few island gems to consider for fall planting.
Salvia cedrosensis, Cedros Island sage: Cedros Island is one of the Mexican Channel Islands on the Pacific side of Baja California. It is generally considered to be the most southerly extent of the California Floristic Province with its Mediterranean climate type. The island receives very little rainfall. The dominant plant community is desert scrub. The island can be shrouded in considerable fog, which supplements the scant rainfall. Many island plants have adapted to this combination of moisture sources with a combination of white, waxy foliage to minimize moisture loss, and fine hairs on the leaves to capture fog-borne moisture. This all renders the Cedros Island sage quite white. It grows as a small, rounded shrub to about two feet. The flowers range from white to lavender. A sunny site in well-draining soil is ideal for this sage. Although considered frost tender, the Cedros Island sage has thrived in the nursery for several years. It is a great choice for a potted island native plant.
Calystegia macrostegia, ‘Anacapa Pink’ Island Morning Glory’: Calystegia macrostegia morning glory is native to coastal regions from Monterey County south into Baja California. This selection is from Anacapa Island off the coast of Ventura County. This mounding vine will eventually reach 15′ in height and about half that in width if given something to climb on. In spring it will be covered with large, pink tinted flowers. The bloom can be extended with dead-heading (removing the spent flowers) and occasional water. ‘Anacapa Pink’ island morning glory prefers full sun and well-draining soil.
Adenostoma fasciculatum, ‘Santa Cruz Island’ Chamise: Chamise is a common member of chaparral plant communities throughout California. This selection was discovered on Santa Cruz Island off the coast of Santa Barbara County. It grows as an upright open shrub with small leaves somewhat like rosemary in appearance and twisted shredding bark. The ‘Santa Cruz Island’ selection grows to about six feet in height. The flowers appear in late spring, covering the plant with a cream white display. A stand of blooming chamise can appear covered with snow. The flowers are popular with many pollinators such as our native bees. Chamise is an adaptable shrub in the landscape as long as sun is provided and excess water avoided. Chamise is quite combustible, and should be avoided where wildfires are a concern.
Lepechinia fragrans, ‘El Tigre’ Fragrant Pitcher Sage: Fragrant pitcher sage grows in the coastal mountains of Ventura and Los Angeles Counties. It is one of only five species that grace California, all but one of which grow south of the Transverse Ranges (“The Grapevine”). Fragrant pitcher sage also grows on several of the Channel Islands. The ‘El Tigre’ selection was taken from the slopes of El Tigre peak on Santa Cruz Island. It grows as an open, somewhat fountain shaped shrub to about six feet, with wide lance-shaped leaves. The leaves are quite fragrant and covered with soft hairs. The new growth of spring will be replaced with smaller leaves as the summer progresses. The lavender flowers are large and tubular, just the right size for bumble bees to access the nectar. Fragrant pitcher sage is best grown in partial shade without supplemental irrigation once established. The ‘El Tigre’ selection is notable for the depth of the flower color.
Acmispon dendroideus var. dendroideus, Island Broom: California’s acmispon genus ranges throughout the state with many forms, from low groundcover to upright, open shrubs. All species share compound leaves with round to lance-shaped leaflets and dramatic, usually yellow, flowers. They also share a preference for dry, sunny sites. The island broom is endemic to the three most northerly Channel Islands (Santa Rosa, San Miguel and Santa Cruz) and Santa Catalina Island. The form varies from place to place, but generally it grows as a mounding shrub up to three feet or so. The leaflets are small and lance-shaped with a coating of fine hairs. The bright yellow flowers make for quite a display as they cover the new growth each spring. Since this Channel Island native grows under substantial ocean influence, protection from the afternoon sun is advisable in interior settings.
Teucrium glandulosum, desert germander, has a rather scant presence in California, occurring only in the Whipple Mountains of eastern San Bernardino County. Its range encompasses the Sonoran Desert from Arizona into Mexico, and the Baja Peninsula. The peninsular distribution includes some of the Mexican Pacific islands. Our plants were grown from a population which was acquired by the Santa Barbara Botanic Garden from Cedros Island. Little Cedros Island is usually included in the California Floristic Province, i.e. the portions of the Pacific Coast of North America that enjoy a Mediterranean climate. Desert germander grows as a loose, open mound of long stems with small lance-shaped leaves arranged oppositely. The ornate flowers appear profusely in the spring and then sporadically throughout the year. Provide desert germander with well-draining soil and some protection from the afternoon sun. Occasional water and dead heading will keep the plant looking its best.