Rosaceae (rose family) Lyonothamnus

Lyonothamnus floribundus subsp. aspleniifolius Santa Cruz Island ironwood

California Channel Islands
Lyonothamnus floribundus subsp. aspleniifolius blooming in early summer on Bowdoin Street. Sairus Patel, 7 Jun 2018
Lyonothamnus floribundus subsp. aspleniifolius leaf. From Trees of Stanford and Environs, Ronald Bracewell

Native to the islands off the Southern California coast, Santa Cruz Island ironwood is a dramatic small tree with fernlike foliage and curiously peeling bark in strips of contrasting browns and grays, interesting to feel. The compound leaves have about five narrow leaflets, each deeply sculpted into triangular lobes. Large clusters of small white flowers are noticeable in summer and remain hung up in an untidy manner for months. The fruit is a ¼-inch woody capsule containing two pairs of seeds. The dense red wood is suitable for small projects.

There are about a dozen on the south side of Bowdoin Street between Pine Hill Road and Stanford Avenue. Uncrowded specimens can be seen in the Stanford Avenue greenbelt, starting from the Santa Fe Avenue bike path to the Sonoma Terrace bike path, and extending to and into the clearing 75 yards south of the Sonoma Terrace bike path (location). A single tree grows at the end of the parking lot between Branner Hall and Kimball Hall; another is at Encina Hall’s northwest corner. A group at the northwest corner of the old Eating Clubs east of Encina was removed when Jack McDonald Hall (Highland Hall) was built in that spot.

It is often misleadingly called Santa Catalina Island ironwood, or some variant thereof. That epithet should be reserved for the rare L. floribundus subsp. floribundus, which has simple, undivided leaves and occurs only on Santa Catalina Island. Subspecies aspleniifolius is restricted to Santa Cruz, San Clemente and Santa Rosa Islands. The fossil record indicates that Lyonothamnus grew in many parts of the western United States in the Tertiary period.

Illustrations: leaf.

Name derivation: Lyonothamnus – After W. S. Lyon, who discovered it in 1884 and Greek thamnos (a shrub); floribundus – profusely flowering; aspleniifolius – with leaves like Asplenium.

About this Entry: The main text of this entry is from the book Trees of Stanford and Environs, by Ronald Bracewell, published 2005. Sairus Patel added the note on common names, ssp. floribundus, and provenance details Jul 2018 (Jepson 2, Griffin & Critchfield). Sairus Patel edited the locations and added Branner; all locations now valid (Jun 2020).