''Lyonothamnus'' is a monotypic genus of trees in the

rose family Rosaceae (), the rose family, is a medium-sized family of flowering plants that includes 4,828 known species in 91 genera. The name is derived from the type genus ''Rosa''. Among the most species-rich genera are '' Alchemilla'' (270), ''Sorbus ...

containing the single living species ''Lyonothamnus floribundus'', which is known by the common name Catalina ironwood, and the subspecies ''L. f.'' ssp. ''aspleniifolius'' and ''L. f.'' ssp. ''floribundus''.

Description

''Lyonothamnus'' is

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found else ...

to the

Channel Islands of California The Channel Islands () are an eight-island archipelago located within the Southern California Bight in the Pacific Ocean, off the coast of California. The four Northern Channel Islands are part of the Transverse Ranges geologic province, ...

, where it grows in the chaparral and oak woodlands of the rocky coastal canyons. This is a tree growing up to tall with peeling reddish gray or brown bark. The evergreen leaves are shiny, dark green with lighter undersides, and borne on short petioles. The two subspecies have different leaf shapes. The

inflorescence An inflorescence is a group or cluster of flowers arranged on a Plant stem, stem that is composed of a main branch or a complicated arrangement of branches. Morphology (biology), Morphologically, it is the modified part of the shoot of sperma ...

is a cluster of woolly white flowers with many short, whiskery stamens. The fruit is a pair of hard follicles. In natural populations on the islands the tree grows in distinct groves.

Isozyme In biochemistry, isozymes (also known as isoenzymes or more generally as multiple forms of enzymes) are enzymes that differ in amino acid sequence but catalyze the same chemical reaction. Isozymes usually have different kinetic parameters (e.g. dif ...

analysis has determined that each grove is a clonal colony in the landscape. Each ironwood clone, or genet, is a group of genetically identical individuals comprising a dozen to several hundred tree trunks, or ramets. Later studies with DNA (RAPD) analysis also found that the trees are clonal. Conservation Because island ironwoods are clonal there are fewer genetic individuals on each island. Isolated clones in the steep rugged terrain can influence cross pollination. Limited cross pollination may be a reason for low seed production/viability observed in natural populations on the island. Genetic integrity of each islands population of ''Lyonothamnus floribundus'' is important. Care must be used by island resource managers to protect the genetic integrity of natural populations by prohibiting introduction of ''Lyonothamnus'' from other islands and/or the mainland (nursery stock). Two introductions of ''L. f. ssp. aspleniifolius'' have occurred on Santa Catalina Island and pose a threat to the native ''L.f. ssp. floribundus'' populations.

Systematics

''Lyonothamnus'' is currently a geographically restricted island

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

containing one

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

with two subspecies. Discoveries of

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

s have suggested that the genus once comprised several species, all but one now extinct, which grew on the mainland in the southwestern United States. Lyonothamnus floribundus floribundus

Subspecies

There are two subspecies which have different leaf morphology, and geographic distributions. *ssp. ''aspleniifolius'' is endemic to Santa Cruz, Santa Rosa, and San Clemente islands, and has palmately to pinnately compound leaves. *ssp. ''floribundus'' is endemic to Santa Catalina Island Catalina Island, has simple linear to oblong, generally entire leaves with sometimes irregular lobes at the base of the leaf. Seedling leaves are often compound, but less so in one year old plus individuals. Note: Spelling descrepency with ''L. f. ssp aspleniifolius'' it is spelled asplenifolius in Jepson Manual (book 1993) and spelled aspeniifolius in JepsoneFlora and Flora of North America.

Cultivation

The ''Lyonothamnus ssp. aspleniifolius'' tree is grown in the horticulture nursery trade and used in

landscape design Landscape design is an independent profession and a design and art tradition, practiced by landscape designers, combining nature and culture. In contemporary practice, landscape design bridges the space between landscape architecture and gard ...

; in

drought tolerant Drought tolerance is the ability to which a plant maintains its biomass production during arid or drought conditions. Some plants are naturally adapted to dry conditions'','' surviving with protection mechanisms such as desiccation tolerance, deto ...

, California native plants, traditional, and habitat-

wildlife garden A wildlife garden (or wild garden) is an environment created by a gardener that serves as a sustainable haven for surrounding wildlife. Wildlife gardens contain a variety of habitats that cater to native and local plants, birds, amphibian ...

s; in public landscapes and private garden settings.Bornstein, Carol; Fross, David; & O,Brien, Bart. "California Native Plants for the Garden'. Cachuma Press, Los Olivos, CA. 2005. p.131.

References

External links

Jepson Manual TreatmentUSDA Plants ProfilePhoto gallery: ssp. ''aspleniifolius''Photo gallery: ssp. ''floribundus''
{{Taxonbar, from1=Q4262384, from2=Q17245437 Amygdaloideae Monotypic Rosaceae genera Endemic flora of California Natural history of the Channel Islands of California Natural history of the California chaparral and woodlands Trees of the Southwestern United States Trees of Mediterranean climate Trees of mild maritime climate Garden plants of North America Drought-tolerant trees Flora without expected TNC conservation status