Best planted along the coast in full to part sun in well to fairly well-drained soil and given infrequent to very little irrigation, but always deeply. In inland gardens it appreciates some shade in the afternoon and more occasional irrigation as well as protection from drying winds. This plant can become chlorotic in heavy soils when given excessive water or where soils do not drain well. Established trees are drought and moderately frost tolerant, taking temperatures down to about 15 degrees F. Older plants can be rejuvenated by cutting down to the basal burl and the hard wood can be used to fashion long lasting garden elements. A great plant for a grove planting or as a specimen where a narrow tree is needed or it can be espaliered with support against a wall, as is done against the library at the Santa Barbara Botanic Garden. Some object to the old flowers that hang on for a long period, but these can be easily removed with a pole saw on smaller plants.

Lyonothamnus floribundus ssp. aspleniifolius is found growing in the wild on rocky substrates primarily northerly facing slopes of Santa Cruz Island with populations also on two other of the Santa Barbara Channel Islands, San Clemente Island and Santa Rosa Island. The subspecies Lyonothamnus floribundus ssp. floribundus, with leaf margins entire, is found only on Santa Catalina Island. The name for the genus is a combination of the Greek word 'thamnos' meaning "shrub" and Lyon to honor William Scrugham Lyon (1851-1916) an early resident of Los Angeles who sent specimens in 1884 of the subspecies floribundus from Santa Catalina Island to Asa Gray, who named the plant in his honor. Lyon and Rev. Joseph Cook Nevin (who Berberis nevinii is named for) collected together on Catalina Island and Lyon later published an island flora in the Botanical Gazette as "Flora of Our Southwestern Archipelago". He was an early Los Angeles area nurseryman, establishing Occidental Nurseries and Elysian Gardens and was appointed the first head of the State Forestry Board. Lyon also explored and collected in Mexico and wrote one of the first California gardening books, Gardening in California, published in 1897. Lee Lenz in Native Plants for California Gardens (Rancho Santa Anna Gardens 1956) noted that Lyonothamnus may have been discovered prior to Lyon's discovery as Professor H.C. Ford of Santa Barbara reported hearing about the Ironwood tree as early as 1875 and Willis Linn Jepson reported in The Silva of California: Memoirs of the University of California, Volume 2 (University Press, 1910) that Katherine Brandegee noted that specimens were sent to Europe by Gustav Eisen with other sources noting that Gustav Eisen discovered it on Santa Catalina Island in 1874 and sent samples to botanists in Europe, but failed to note its taxonomic significance and was therefore not credited with the find. The specific epithet 'floribundus' means "abundant flowering".

Lyonothamnus floribundus ssp. floribundus from Santa Catalina Island, with leaf margins entire, is very rare and not generally considered as attractive as the subspecies aspleniifolius whose epithet means "leaves like Asplenium fern". This subspecies was first described as a species by the American botanist Edward Lee Greene and later reduced to a subspecies by Townshend Stith Brandegee. It was first reportedly brought back from Santa Cruz Island to the mainland by the Italian born botanist Dr. Francesco Franceschi (AKA Emanuele Orazio Fenzi), who transported a burl stump back to Santa Barbara in 1994 and plants propagated from suckers off this plant were distributed throughout California by 1905. It was also reported that Franceschi returned with seed and that a large specimen at the Botanic Garden of the University of California, Berkeley was grown from this seed - other reports are that this Berkeley plant was grown from cuttings off of Franceschi's burl stump and that the collection date of the plant may have been as late as 1900 however Harry M. Butterfield in his Dates of Introduction of Trees and Shrubs to California lists UC Berkeley as having the plant in 1898. Studies showing extremely low seed viability on the island populations would seem to indicate that the early plants may have been mainly propagated vegetatively but nearly all nursery crops today are produced from seed.

Fossil evidence shows that Lyonothamnus was more widely distributed throughout mainland California up until around 6 million years ago, but now is restricted to only four of the Santa Barbara Channel Islands. In 1935 this plant was adopted county Board of Supervisors as the official tree of Santa Barbara County. It is interesting to note that botanical authors Greene, Brandegee and Raven in the past have all spelled the subspecies epithet "asplenifolius" with a single "i" in the middle but this spelling has been determined incorrect and in the recent Jepson manual treatment it is now "aspleniifolius" with a double "i". This plant has long been commonly called Catalina Ironwood in the nursery trade, but this is a misnomer as this this name should only apply to the plant native to Catalina Island, Lyonothamnus floribundus ssp. floribundus while the subspecies aspleniifolius should really be called Santa Cruz Island Ironwood. Another common name for this plant is Fern-leaf Ironwood. We have grown and sold this plant continuously since 1981. 

This information about Lyonothamnus floribundus ssp. aspleniifolius displayed is based on research conducted in our horticultural library and from reliable online resources. We also will relate observations made about it as it grows in our nursery gardens and other gardens we have visited, as well how the crops have performed in containers in our nursery field. We will also incorporate comments that we receive from others and we welcome hearing from anyone with additional information, particularly if they can share any cultural information that would aid others in growing it.