Home
Advanced Search Map Locator View Settings
Add Current Plant To List Edit Current Plant
Show all Photos

My Plant Lists Nurseries Planting Guide Contact Calscape About Calscape
Tap map to see plants native to location
Order by Popularity Order by Common Name Order by Botanical Name
Show nursery cultivars Hide nursery cultivars
Show plants not in nurseries Hide plants not in nurseries
Grid view Text view
Loading....
Poisonoak
Toxicodendron diversilobum
  


About Poisonoak (Toxicodendron diversilobum) Toxicodendron diversilobum, commonly named poison oak, Pacific poison oak or western poison oak, is a woody vine or shrub widely distributed in western North America. It is common in various habitats, from riparian zones to dry chaparral. It thrives in shady and dappled light through full and direct sunlight conditions. It is one of the more common shrubs in California, growing throughout the coastal and coast mountain ranges, the Transverse mountain ranges, through the Sierra foothills, and in the Sacramento Valley. It is extremely variable in growth habit and leaf appearance, growing as a dense tall shrub in open sunlight, and a treelike vine or dense thickets in shaded areas. It reproduces by spreading rhizomes and by seeds. The plant is winter deciduous, so that after cold weather sets in, the stems are leafless and bear only the occasional cluster of berries.

Poison oak is known for causing itching and allergic rashes in many humans after contact by touch or smoke inhalation. Because of this, it is usually eradicated from gardens and public landscaped areas. However, it can be a carefully situated component in wildlife gardens, habitat gardens, and natural landscaping. The plant is used in habitat restoration projects. It can be early stage succession where woodlands have been burned or removed, serving as a nurse plant for other species.
Botanist John Howell observed the toxicity of Poison Oak obscures its merits: "In spring, the ivory flowers bloom on the sunny hill or in sheltered glade, in summer its fine green leaves contrast refreshingly with dried and tawny grassland, in autumn its colors flame more brilliantly than in any other native, but one great fault, its poisonous juice, nullifies its every other virtue and renders this beautiful shrub the most disparaged of all within our region."

Black-tailed deer, mule deer, California ground squirrels, western gray squirrels, and other indigenous fauna feed on the leaves of the plant. It is rich in phosphorus, calcium, and sulfur. Bird species use the berries for food, and utilize the plant structure for shelter. Neither native animals, nor horses, livestock, or canine pets demonstrate reactions.
Plant Description
Plant Type
Shrub, Vine

Max. Height
1.6 - 13 ft (0.49 - 4 m)

Max. Width
13 ft (4.0 m)

Form
Mounding, Rounded, Upright Columnar, Weeping

Fragrance
Slight

Growth Rate
Fast

Dormancy
Winter Deciduous

Flower Color
White

Flowering Season
Spring
Spring
Summer
Fall
Winter


Native Status
Native

Natural Setting
Site Type
Canyons or woodlands

Sun
Sun, Part Shade

Elevation ?
-3' - 7187'

Annual Precip. ?
7.0" - 117.2"

Summer Precip. ?
0.15" - 2.78"

Coldest Month ?
34.2° F - 56.5° F

Hottest Month ?
56.3° F - 80.6° F

Humidity ?
0.03 vpd - 28.41 vpd

Soil Description
Adaptable

Drainage
Fast, Medium, Slow

Wildlife Attracted
Black-tailed deer, mule deer, California ground squirrels, western gray squirrels, and other indigenous fauna feed on the leaves of the plant. It is rich in phosphorus, calcium, and sulfur. Bird species use the berries for food, and utilize the plant structure for shelter. Neither native animals, nor horses, livestock, or canine pets demonstrate reactions.

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


Popularity
Never or Almost Never Used

Common uses
Bird Gardens

Nursery Availability
Commonly Available

Other Names
Common Names
Pacific Poison Oak



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


Sign in to your Calscape Account X




Once signed in, you'll be able to access any previously saved plant lists or create new ones.

Email Address
Password

Sign In