Ironwood Trees

Island ironwood (Lyonothamnus), a tree in the rose family, was first collected on Santa Catalina Island in 1884 by William S. Lyon, and given its generic name in his honor by Dr. Asa Gray of Harvard University. In 1886, botanist E. L. Greene visited Santa Cruz Island where he determined a tree reported by Barclay Hazard in the summer of 1885 was in fact a new species of Lyonothamnus.

In 1888 T. S. Brandegee found the same species on Santa Rosa Island, where he states “the trees were small and often distorted by the wind.” Known to botanists as Lyonothamnus floribundus, it is found growing naturally only on the islands of Santa Catalina, San Clemente, Santa Rosa and Santa Cruz.

The subspecies floribundus, with entire leaflets, occurs only on Santa Catalina Island, and the subspecies asplenifolius, with toothed fern-like leaflets, is restricted to Santa Cruz, Santa Rosa and San Clemente islands.

Island ironwood trees survive as a relic of a species which once had an extensive distribution along the mainland, but became extinct. Island ironwood was adopted as the official tree of Santa Barbara County by the Board of Supervisors on August 30, 1935. This action was the result of a recommendation made by the Directors of the Blaksley Botanic Garden to the Native Sons of the Golden West as a part of a movement to stimulate a wider interest in the use of native trees in gardens and parks (September 1935 Santa Barbara Museum of Natural History Leaflet).

» Ford, Henry Chapman “The Lyonothamnus asplenifolius” in Bulletin of the Society of Natural History 1:2, 56-58, 1890.

In the News~

April 21, 1895 [LAT/SB]: “Exhibition of flowers… Among the more interesting specimens shows a tiny fern-like seedling, the first attempt at artificial cultivation of the famous ironwood tree indigenous to Santa Cruz, one of our Channel Islands, and which is not only found nowhere else upon the globe, but which has not a single botanical relative, and has therefore created a new botanical genus, named Lyonothamnus asplenifolius, after a Los Angeles gentleman, Mr. Lyon, who was the first to bring this tree to the notice of scientific men. The tree is a very stately species, with a fern-like foliage, and grows to a height of fifty feet in its wild state.”

May 1929 Santa Barbara Museum of Natural History Leaflet:

“Through the courtesy of Mr. Smith, the superintendent of the Vail Ranch, the Director (Ralph Hoffmann) was enabled to camp in the interior of the island, in Lobo Canyon at the base of Black Mountains. From this base camp, the ridge of Black Mountain, Green, Soledad and Elder Canyons were explored.” Hoffmann found “one wind-blown Ironwood (Lyonothamnus) in Elder Canyon.”