Catalina Ironwood

By Linda Lewis Griffith UCCE Master Gardener

Lyonothamnus floribundus

Common Name: Catalina Ironwood

Planting Zone: Sunset Zones 14-17, 19-24

Size:  20-50 ft. tall, 25-35 ft. wide

Bloom Season: Late spring or early summer

Exposure: Full sun

Pruning Needs:  Prune in winter to manage shape and growth

Water Needs: Moderate amounts of water are needed from winter through spring; low amounts of water are needed during summer

Narrative:This beautiful, evergreen tree is native to the Channel Islands, where it grows on north facing slopes and canyon habitats from sea level to 1600 ft. in elevation.  It is the only species of this genus.  But over time, two subspecies have evolved.  Lyonothamnus floribundus ssp. asplenifolius is known as Fern-leaf Catalina ironwood and is found on San Clemente, Santa Rosa and Santa Cruz Islands.  Its leaves are deep green above, gray and hairy beneath and pinnately or palmately divided into 3-7 deeply notched or lobed leaflets.  L. f. ssp. floribundus is native to Catalina Island. Mature foliage consists of simple, linear leaves, 3-7 inches long with finely toothed margins.  Both varieties are found in cultivation and can hybridize with each other.  The bark is red-brown and peels and shreds with age, revealing smooth, new bark underneath.  Flowers appear as small, flat clusters of white blossoms, 8-18 inches wide.  Old clusters eventually turn brown and can remain on the tree for years.  When practical it's best to remove them. Fern-leaf Catalina ironwood is the most commonly grown subspecies and thrives in well-drained soil in coastal and adjacent inland zones throughout the state.  It will survive in warmer climates if provided adequate drainage and periodic deep watering.  It is often planted along roadways with other native plants or used to create attractive screens or groves.  Excessive litter from flowers, leaves and bark can make it a poor choice in more manicured environments. Chlorosis, or yellowing leaves, may be a problem in heavy soils. Lyonothamnus is named for William S. Lyon, a 19^th century resident of Los Angeles and a collector of plants from Santa Catalina Island.  Thamnos is a Greek word meaning shrub.  Floribundus means free-flowering.