Santa Cruz Ironwood

The Island Tree Has Tiny White Flowers Resembling Miniature Roses

Santa Cruz ironwood (<em>Lyonothamnus floribundus</em>).

All plants have a story. That story may consist of information about its first discovery or its loss and rediscovery. It might be a list of the uses that humans (or animals) have found for it, be they medicinal, useful, or even spiritual. Amusing or interesting anecdotes about plant names abound, and evolutionary history, including fossil records, global or local distribution patterns, which might be ancient or recent, can all be fascinating. The recent rise of landscaping for purely pleasurable reasons adds another dimension to some plants’ stories.

Santa Cruz ironwood (Lyonothamnus floribundus) has a complex story that pulls from nearly all of those categories of interest. It was first collected for classification by western taxonomists in 1885 by Barclay Hazzard, who was instrumental in organizing trips to the Channel Islands in those early days of Santa Barbara history. It became clear early on that the species was restricted to Santa Cruz, Santa Rosa, San Clemente, and Santa Catalina islands, where it is now an endemic species of tree, not growing naturally anywhere else. What is interesting about this current distribution is that, in the geologic past, this species grew in a much wider area of western North America until about 6 million years ago, when conditions became drier overall.

Also of interest is the fact that it has no other close living relatives. This unique tree is in the rose family, and its tiny white flowers resemble miniature simple roses. They are held in large, flattened clusters and just now are clothing the tree in a myriad of nosegays. These will eventually fade and turn brown. This fact is distressing to some gardeners, who think the dull-brown decorations are somewhat unsightly. In the landscape, they can be removed if necessary, but will eventually drop of their own accord.

The most commonly planted form of Santa Cruz Island ironwood is actually a subspecies aptly named asplenifolius (leaves like spleenwort) because of the resemblance of its very divided leaves to several different species of ferns commonly referred to as spleenworts. The silhouette of the ironwood leaf has been for years the logo of the Santa Barbara Botanic Garden in spite of its vague resemblance to the leaves of marijuana. Ironwood leaves are quite leathery and have no other, chemical ties to the intoxicating “weed.”

To close out the story of this unique native, the effort that was needed to bring it into cultivation is also remarkable. The notable Italian horticulturist Francesco Franceschi, who spent a scant 20 years in Santa Barbara, but who altered the landscape here forever with his penchant for bringing exotic plants to the area, was also responsible for taming the wild ironwood. After repeated attempts to grow the tree from seed, Franceschi eventually transplanted an actual living tree to the mainland and eventually hit on the appropriate technique to propagate it for sale.

In the 1930s, Santa Cruz Island ironwood became the official tree of Santa Barbara County, but it is still rather scarce in the landscape and deserves a much wider use. It is an upright tree that doesn’t grow too wide, but can eventually reach about 40 to 50 feet in height. It has handsome, peeling bark that shades from reddish-brown to gray as it ages. And the flowers are a lovely late-spring, early-summer delight. Occasional chlorosis (yellowing of the leaves) results from planting in very heavy soil, so choose a well-drained site.


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