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You are here >1Up Info > Wildlife, Animals, and Plants > Plant Species > Shrub > Species: Toxicodendron diversilobum | Poison-Oak

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SPECIES: Toxicodendron diversilobum | Poison-Oak
GENERAL BOTANICAL CHARACTERISTICS : Poison-oak is a many-stemmed, deciduous, native shrub or woody vine. Shrubs are erect with stems from 2 to 6 feet (1-2 m) tall. Vine stems commonly reach 10 to 30 feet (3-10 m), but may be as long as 100 feet (30 m) [22]. As a vine, poison-oak climbs trees or other support by adventitious roots and/or wedging stems within grooves or crevices of the support [7,22,62]. The bright green leaves have three (sometimes five) round to ovate, diversely lobed or toothed leaflets that usually resemble oak leaves [45,62]. Small flowers occur in leaf axils, with male and female flowers on separate plants [38,53]. The fruits are white drupes [45]. Rhizomes are at or just below the soil surface, and are extensive [46]. RAUNKIAER LIFE FORM : Phanerophyte Hemicryptophyte REGENERATION PROCESSES : Poison-oak reproduces vegetatively by sprouting from the rhizomes and root crown after disturbance such as fire or browsing has removed topgrowth [15,44,53]. It also reproduces by layering when vine stems contact the ground [46]. Poison-oak seeds are dispersed by birds [53]. Seedlings occur both before and after fire, suggesting that the seeds do not depend upon fire for scarification. The seeds have a gummy seedcoat which leaches off very slowly, resulting in delayed germination [37]. Poison-oak is propagated by stem cuttings [23]. SITE CHARACTERISTICS : Poison-oak generally grows in acid soils, and is not limited to any particular soil texture or drainage pattern. It occurs on well-drained slopes and in riparian zones [1,39,64]. It is found at elevations of less than 5,000 feet (1,524 m) west of the Sierra Nevada, growing on all aspects [45]. In the Siskiyou Mountains it is found at up to 4,400-foot (1,340-m) elevations on steep southern exposures [66]. SUCCESSIONAL STATUS : Facultative Seral Species Poison-oak is a somewhat shade-tolerant species commonly occurring in seral woodland and mixed evergreen forest understories [51,56]. It is considered a climax species on south-slope Douglas-fir forests of the Willamatte Valley foothills, Oregon [51]. In climax oak woodland, poison-oak cover may reach 25 to 50 percent [17]. SEASONAL DEVELOPMENT : Poison-oak leaf buds open from February to March, and stems elongate from March to April [37]. Flowering occurs from from March to June [15]. Leaves drop from late July to early October [22], and fruits disperse in summer and fall [37,53].

Related categories for Species: Toxicodendron diversilobum | Poison-Oak

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Information Courtesy: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory. Fire Effects Information System

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