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California redbud is a native , deciduous [35,44,72] shrub-tree [11,36,48,49,54,64]. It can appear as a tree with arching canopies that almost reach the ground or a considerably shorter, many-stemmed shrub [68,72]. Plants generally occur singly, but they may form thickets in riparian zones .
California redbud plants are commonly from 7 to 20 feet (2-5 m) tall [35,54,55,76]. The tallest California redbud on record is 29 feet (8.8 m) . The stems are clustered and erect [36,54,55] and predominantly leafless . During the 1st year of life, California redbud stems are covered in hairs . The inflorescence is a 2- to 5-flowered raceme . The flowers are 8 to 12 mm long [54,55] and appear before the leaves [20,40,76]. The seedpod is a flat legume from 2 to 4 inches (4-9 cm) long and 0.8 to 1 inch (2-2.5 cm) wide [54,55]. Each seedpod contains 7 seeds  from 3 to 4 mm in diameter [54,55]
California redbud is intermediately tolerant of flooding in semiarid riparian zones. Intermediately tolerant is defined as a species that "is able to survive flooding for periods between 1 to 3 months during the growing season. The root systems of these plants may produce few new roots or will be dormant during the flooded period" .RAUNKIAER  LIFE FORM:
Pollination: California redbud is pollinated by bumble bees and orchard mason bees [11,24,72].
Breeding system: The flowers of California redbud are dioecious .
California redbud produces abundant crops of legumes, but seed set is variable . Seed dispersal:
California redbud seeds are dispersed by wind, birds, and animals . Seed banking:
California redbud utilizes a seed bank . Germination:
J.S. Peterson @ USDA-NRCS PLANTS DATABASE
Seed production: California redbud produces abundant crops of legumes, but seed set is variable .
Seed dispersal: California redbud seeds are dispersed by wind, birds, and animals .
Seed banking: California redbud utilizes a seed bank .
Germination:California redbud seeds require scarification and stratification for germination [44,48,53]. The seeds are adapted to prolonged periods of dryness and cold due to an impervious seed coat and a dormant embryo [1,34,72].
There are no field studies of California redbud seed longevity to date (2006); however, California redbud seeds remained viable for 12 years or more when stored in a freezer at 5% to 9% humidity and 0°F (-18 °C) .
Seedling establishment/growth: California redbud seedlings have a "rapid" growth rate .
Asexual regeneration: California redbud may regenerate asexually by sprouting from boles damaged by fire .SITE CHARACTERISTICS:
In the foothills of northern California, California redbud occurs at low elevations on north-facing slopes or near seasonal water courses .
Climate: California redbud is light and drought tolerant [44,72]. In California chaparral sites, California redbud persists where the winters are cool and wet and the summers are hot and dry .
Elevation: The elevation ranges for California redbud in the 4 states where it occurs are presented in the table below:
|Arizona||4,000 to 6,000 feet [40,49]|
|California||400 to 5,000 feet [35,54,55]|
|Nevada||2,500 to 6,200 feet |
|Utah||2,168 to 4,053 feet [21,76]|
Soil: California redbud can tolerate a wide range of soils [68,72]. In California chaparral, California redbud is found on granitic soils .SUCCESSIONAL STATUS:
At Ellis Ranch, California, California redbud occurs on "early succession" burn sites [29,50]. California redbud is an important species in the late-seral conifer forest-chaparral association of northern California .SEASONAL DEVELOPMENT:
Fire regimes: Research literature on California redbud is primarily centered on its occurrence in California chaparral and oak woodlands. Both of these community types can have lightning-ignited fires and have long been affected by anthropogenic fire, starting with Native Americans [2,42,43]. Prior to European settlement, the western Mono, foothill Yokuts, and Miwok Native Americans of the central and southern Sierra Nevada foothills set autumn fires at intervals of 1 to several years to induce rapid elongation of young growth of California redbud (see Other Uses) [1,2,4,5,6]. They also actively burned to keep down shrubs and trees and maintain an open, park-like woodland that aided hunting and favored certain food crops . Fire exclusion policies were implemented as European settlers entered the area in the late 19th century, again altering the chaparral and oak woodland communities [3,4]. With so much historical human interference in the oak woodlands and chaparral of California, gauging the historic or presettlement fire return interval in these communities is difficult and often debated. In a review by Keeley , evidence is offered that fire frequency in California chaparral has increased, not decreased, due to human-caused accidental fires (see Fire Management Considerations).
In oak woodlands, California redbud is often found in canyon live oak (Quercus chrysolepis), blue oak-gray pine (Q. douglasii-Pinus sabiniana), and interior live oak (Q. wislizenii) community types. The fire return interval in these communities is from <35 to <100 years . The fire return interval of stand-replacement fires in California chaparral varies, depending upon species composition. In reviews, Keeley and Keeley [41,43] stated that modal frequency of stand-replacement fires in California chaparral ranges from 20 to 30 years, and Paysen and others  reported fire return intervals ranging from less than 35 years to about every 100 years. Relatively long fire-return intervals are typical of chaparral dominated by obligate seeding species such as waveyleaf ceanothus (Ceanothus foliosus) , while relatively short fire-return intervals favor spouting chaparral species such as chamise [41,43].
The following table provides fire return intervals for plant communities and ecosystems where California redbud is important. Find fire regime information for the plant communities in which this species may occur by entering the species name in the FEIS home page under "Find Fire Regimes".
|Community or Ecosystem||Dominant Species||Fire Return Interval Range (years)|
|California chaparral||Adenostoma and/or Arctostaphylos spp.||<35 to <100|
|sagebrush steppe||Artemisia tridentata/Pseudoroegneria spicata||20-70|
|coastal sagebrush||Artemisia californica||<35 to <100|
|grama-galleta steppe||Bouteloua gracilis-Pleuraphis jamesii||<35 to <100|
|blue grama-tobosa prairie||Bouteloua gracilis-Pleuraphis mutica||<35 to <100|
|California montane chaparral||Ceanothus and/or Arctostaphylos spp.||50-100 |
|curlleaf mountain-mahogany*||Cercocarpus ledifolius||13-1,000 [9,66]|
|mountain-mahogany-Gambel oak scrub||Cercocarpus ledifolius-Quercus gambelii||<35 to <100|
|Arizona cypress||Cupressus arizonica||<35 to 200|
|western juniper||Juniperus occidentalis||20-70 |
|pine-cypress forest||Pinus-Cupressus spp.||9-63 [7,70,74]|
|pinyon-juniper||Pinus-Juniperus spp.||<35 |
|Colorado pinyon||Pinus edulis||10-400+ [28,31,41,57]|
|Jeffrey pine||Pinus jeffreyi||5-30|
|Pacific ponderosa pine*||Pinus ponderosa var. ponderosa||1-47 |
|interior ponderosa pine*||Pinus ponderosa var. scopulorum||2-30 [8,10,47]|
|galleta-threeawn shrubsteppe||Pleuraphis jamesii-Aristida purpurea||<35 to <100 |
|California mixed evergreen||Pseudotsuga menziesii var. menziesii-Lithocarpus densiflorus-Arbutus menziesii||<35|
|California oakwoods||Quercus spp.||<35 |
|oak-juniper woodland (Southwest)||Quercus-Juniperus spp.||<35 to <200 |
|coast live oak||Quercus agrifolia||2-75 |
|canyon live oak||Quercus chrysolepis||<35 to 200|
|blue oak-foothills pine||Quercus douglasii-P. sabiniana||<35|
|Oregon white oak||Quercus garryana||<35 |
|California black oak||Quercus kelloggii||5-30 |
|interior live oak||Quercus wislizenii||<35 |
While there is little scientific information regarding California redbud's response to fire, Native Americans in the Sierra Nevada burned California redbud every several years, or even annually, to promote growth of young sprouts (see Other Uses) [1,2,3,4,5,6]. Further, a summer prescription fire in an interior live oak-gray pine community promoted California redbud sprouting or establishment from seed in postfire years 1, 2, and 3 . This suggests that fire promotes California redbud sprouting.
With such a dearth of information regarding California redbud response to fire, further fire research is sorely needed on this plant species.DISCUSSION AND QUALIFICATION OF PLANT RESPONSE:
|Preproject 1986||Postpreparation 1987||Postfire month 2||Postfire year 1||Postfire year 2||Postfire year 8|
Palatability/nutritional value: No information is available on this topic.
Cover value: Currently (2006) there is no literature addressing the cover value of California redbud. However, given its height [35,54,55,76] and arching canopy [68,72], it likely provides cover for a variety of mammal and bird species.VALUE FOR REHABILITATION OF DISTURBED SITES:
There is 1 California redbud cultivar ('common') available .OTHER USES:
California redbud is often used as a landscaping ornamental [11,20,72].OTHER MANAGEMENT CONSIDERATIONS:
Insects: The red humped caterpillar is a common defoliator of California redbud plants in California [17,52,58,60,61]. The larvae of red humped caterpillars can consume an average of 0.4 inch˛ of California redbud foliage per day . Bacillus thuringiensis, an insecticidal bacterium, can control red humped caterpillar larvae [17,17,58,60,61].
Bacillus thuringiensis is also an effective deterrent for the fruit tree leafroller, which causes serious leaf defoliation in California redbud plants .Fungus: California redbud is highly susceptible to a fungal canker caused by Botryosphaeria ribis and B. dothidea [62,65].
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