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Lyonothamnus floribundus

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About Island Ironwood (Lyonothamnus floribundus) Island Ironwood (Lyonothamnus floribundus) is a native tree that grows in Southern and Central California, primarily in the Channel Islands region. It tends to grow in rocky slopes, at elevations from 100-1600 feet. Lyonothamnus is endemic to the Channel Islands of California, where it grows in the chaparral and oak woodlands of the rocky coastal canyons.

This is a tree growing up to 15 metres (49 ft) 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 leaves of different leaf shapes. Ssp. asplenifolius (Santa Cruz Island Ironwood) has incised, fern-like leaves and is the more commonly available in horticultural form. Ssp. floribundus (Catalina Island Ironwood) has smooth, undivided leaves and is seldom seen in gardens. The inflorescence of both is a cluster of woolly white flowers with many short, whiskery stamens. The fruit is a pair of hard follicles.
Plant Description
Plant Type

Max. Height
25 - 50 ft (7.6 - 15.2 m)

Max. Width
15 - 24 ft (4.6 - 7.3 m)

Upright Columnar


Growth Rate


Ssp. asplenifolius produces considerable leaf litter which is useful as a mulch but can bury small understory plants

Flower Color
Cream, White

Flowering Season
Spring, Summer

Native Status

Natural Setting
Site Type
Rocky slopes


Elevation ?
-480' - 13935'

Annual Precip. ?
4.0" - 90.9"

Summer Precip. ?
0.14" - 4.24"

Coldest Month ?
8.7° F - 58.5° F

Hottest Month ?
32.5° F - 87.4° F

Humidity ?
1.19 vpd - 38.76 vpd

Soil Description
This tree is tolerant of a variety of garden soils as long as drainage is reasonably good

Soil Texture
Loam, Loamy Sand, Sand, Sandy Loam, Silt Loam

Soil PH
5.0 - 8.0

Fast, Medium

Cold Tolerance(° F)
Tolerates cold to 22° F

Wildlife Attracted
Numerous birds and insects are attracted to the flowers

Landscaping Information
Water Requirement ?
Very Low
Extremely Low
Very Low
Moderate - High

Moderately Popular

Max. Summer Water ?

No Summer Water
Keep moist

Organic with Rocks

Propagation ?
For propagating by seed: Place seeds in about 6 times their volume of 140°F wa ter then let cool about 45 mins. before sowing ( Maunsell Van Rensselaer correspondence to Howard McMinn 1947). No treatment. gives fair germination.

Common uses
Bank Stabilization, Hedges

Nursery Availability
Commonly Available

Other Names
Common Names
Catalina Ironwood

Sources include: Wikipedia. All text shown in the "About" section of these pages is available under the Creative Commons Attribution-ShareAlike License. Plant observation data provided by the participants of the California Consortia of Herbaria, Sunset information provided by Jepson Flora Project. Propogation from seed information provided by the Santa Barbara Botanical Garden from "Seed Propagation of Native California Plants" by Dara E. Emery. Sources of plant photos include CalPhotos, Wikimedia Commons, and independent plant photographers who have agreed to share their images with Calscape. Other general sources of information include Calflora, CNPS Manual of Vegetation Online, Jepson Flora Project, Las Pilitas, Theodore Payne, Tree of Life, The Xerces Society, and information provided by CNPS volunteer editors, with special thanks to Don Rideout. Climate data used in creation of plant range maps is from PRISM Climate Group, Oregon State University, using 30 year (1981-2010) annual "normals" at an 800 meter spatial resolution.

Links:   Jepson eFlora Taxon Page  CalPhotos  Wikipedia  Calflora

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