''Lyonothamnus'' is a monotypic genus of trees in the rose family 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 only 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 foun ...

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. They define the Santa Barbara Channel between the islands and the California mainland. The ...

, 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 In botany, an inflorescence is a group or cluster of flowers arranged on a plant's Plant stem, stem that is composed of a main branch or a system of branches. An inflorescence is categorized on the basis of the arrangement of flowers on a mai ...

is a cluster of woolly white flowers with many short, whiskery

stamen The stamen (: stamina or stamens) is a part consisting of the male reproductive organs of a flower. Collectively, the stamens form the androecium., p. 10 Morphology and terminology A stamen typically consists of a stalk called the filament ...

s. The fruit is a pair of hard follicles. In natural populations on the islands the tree grows in distinct groves. Isozyme analysis has determined that each grove is a

clonal colony A clonal colony or genet is a group of genetically identical individuals, such as plants, fungi, or bacteria, that have grown in a given location, all originating vegetatively, not sexually, from a single ancestor. In plants, an individual in ...

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 island’s 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 (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

containing one

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

with two

subspecies In Taxonomy (biology), biological classification, subspecies (: subspecies) is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (Morphology (biology), morpholog ...

. 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 preserve ...

s have suggested that the genus once comprised several species, all but one now

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

, 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 garde ...

; in drought tolerant, California native plants, traditional, and habitat-

wildlife garden A wildlife garden (or habitat garden or backyard restoration) is an Biophysical environment, environment created with the purpose to serve as a sustainable haven for surrounding wildlife. Wildlife gardens contain a variety of habitats that cater t ...

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. Lyonothamnus_floribundus_subsp

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 Northern America Trees of Mediterranean climate Trees of mild maritime climate Garden plants of North America Drought-tolerant trees Flora without expected TNC conservation status