Weed Information: Toxicodendron radicans (poison-oak, eastern)
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Toxicodendron radicans (poison-oak, eastern)

Family: Anacardiaceae

Description

The taxonomy of this group is extremely difficult as the species have been placed in the genus Rhus as well as the genus Toxicodendron. There are also many subspecies and varieties, some of which seem to hybridize. The plants vary from low shrubs to climbing vines which helps to account for the fact that several species are referred to as both `poison-oak` and `poison-ivy.` An interesting fact is that both sensitivity and immunity vary with time as well as with individuals. In other words, someone who is immune today, may be susceptible tomorrow!

Characteristics

Flower Color
  • Yellow-green
  • Green
  • White
Inflorescence Type (How the flowers are arranged on the plant)
  • Axillary cluster
  • Panicle
Number of Petals
  • 5 petals
Petal Separation
  • Completely free to base
Petal Tip
  • Pointed
  • Rounded
Flower Symmetry
  • Flowers regular
Flower Length (Head length in the Asteraceae)
  • 1 mm (.04 inch)
  • 2 mm (.08 inch)
  • 3 mm (.12 inch)
Flower Width (Head width in the Asteraceae)
  • 2 mm (.08 inch)
  • 3 mm (.12 inch)
Number of Sepals
  • 5 sepals
Sepal Separation
  • Completely free to base
Sepal Tip
  • Pointed
  • Rounded
Flower Sex
  • Bisexual (perfect)
Number of Styles
  • 1 style
Number of Stamens
  • 5 stamens
Stamens Attached to the Petals
  • Stamens NOT attached to the petals
Stamens Connate (united)
  • Filaments or anthers NOT united

Carpel Separation
  • Carpels united (or one)
Number of Carpels
  • 1 carpel
  • 3 carpels
Ovary Position
  • Superior (hypogynous)
Fruit Type
  • Berry, white
  • Berry, yellow\orange\brown
Fruit Length at Maturity
  • 3 mm (.12 inch)
  • 4 mm (.16 inch)
  • 5 mm (.20 inch)
Fruit Width at Maturity
  • 3 mm (.12 inch)
  • 4 mm (.16 inch)
  • 5 mm (.20 inch)
Burs
  • Fruit or seed NOT bur-like

Leaf Arrangement
  • Alternate
Leaf Type
  • Trifoliolate (3 leaflets)
Stipules
  • Lacking
Tendrils
  • Tendrils absent
Venation
  • Pinnate
Petiole (leaf stem) Blade Ratio
  • Petiole 25% - 75% total length
Leaf Length (blade PLUS petiole)
  • 4 - 10 cm (1.60 - 4.0 inches)
  • 1 - 2 dm (4.0 - 8.0 inches)
  • 2 - 4 dm (8.0 - 16.0 inches)
Leaf Width
  • 4 - 10 cm (1.6 - 4.0 inches)
  • 1 - 2 dm (4.0 - 8.0 inches)
  • 2 - 4 dm (8.0 - 16.0 inches)
Leaf or Leaflet Margin
  • Crenate
  • Entire
Leaf or Leaflet Blade Base
  • Acute (cuneate)
  • Rounded
Leaf or Leaflet Tip
  • Acuminate (attenuate)
  • Acute
Leaf or Leaflet Blade Surface
  • Glabrous (NO hairs)
  • Pubescent
Succulence
  • Not succulent

Milky Juice
  • Juice milky
Woodiness
  • Woody
Spines or Thorns
  • Spines or Thorns ABSENT
Aromatic (vegetative structures)
  • Not aromatic
Life Cycle
  • Perennial
Growth Habit (while flowering)
  • Erect, columnar (narrow)
  • Erect, spherical (bushy)
  • Climbing vine
Plant Height at Maturity
  • 4 - 6 dm (1.3 - 2.0 feet)
  • 6 - 8 dm (2.0 - 2.6 feet)
  • 8 - 10 dm (2.6 - 3.3 feet)
  • 1 - 1.5 meters (3.3 - 5.0 feet)
  • 1.5 - 2.0 meters (5.0 - 6.6 feet)
Wind Dissemination
  • Not wind disseminated
Moisture Regime
  • Seasonally saturated
  • Mesic
Chlorophyll
  • Present

Stem Cross Section
  • Round
Flowering Stem Leaves
  • Stem uniformly leafy
Main Stem Branches
  • Main stem unbranched
  • Main stem branched

Root or Vegetative Propagule
  • Rhizomatous
  • Rooting at the nodes
  • Tap Root

US State
  • Alabama
  • Arkansas
  • Connecticut
  • Delaware
  • Florida
  • Georgia
  • Illinois
  • Kansas
  • Kentucky
  • Louisiana
  • Massachusetts
  • Maine
  • Michigan
  • Missouri
  • Mississippi
  • North Carolina
  • New Hampshire
  • New Jersey
  • New York
  • Ohio
  • Pennsylvania
  • South Carolina
  • Tennessee
  • Texas
  • Virginia
  • Wisconsin
  • West Virginia
  • Indiana
  • Maryland
  • Rhode Island
  • Vermont
  • Arizona
  • Iowa
  • Minnesota
  • Oklahoma
  • South Dakota
  • Nebraska
Other
  • District of Columbia
Canadian Province or Territory
  • New Brunswick
  • Nova Scotia
  • Ontario
  • Prince Edward Island
  • Quebec

  • The Biology of Canadian Weeds: Canadian Journal of Plant Science Vol:57Pg.515
  • Common Weeds of Canada, Mulligan 1987 (ISBN 0-910053-59-9) See page: 73
  • Common Weeds of the Canadian Prairies, 1963 (Cat# A53-1136-1) See page: 55
  • Common Weeds of the United States, 1971 (ISBN 0-486-20504-5) See page: 256
  • Field Guide To The Common Weeds Of Kansas, 1983 (ISBN 0-7006-0233-X) See page: 77
  • Gilkey`s Weeds of the Pacific Northwest, 1980 (ISBN 0-88246-039-0) See page: 189
  • How to Know the Weeds, 1972, (ISBN# 0-697-04880-2) See page: 95
  • Identification Guide to the Weeds of Quebec, 1999 (ISBN# 2-89457-174-7) See page: 214
  • Manual of Ohio Weeds, 1931 Ohio Ag. Exp. Station Bull. # 475, See page: 66
  • Nebraska Weeds, 1979 Nebraska Dept. of Ag., Lincoln NE, See page: 115
  • Northwest Weeds, 1990 (ISBN 0-87842-249-8) See page: 75
  • Ontario Weeds, 1992 Agdex 640, Publication #505 See page: 136
  • Representative Missouri Weeds and Their Control, 1941 Univ. of Missouri Ag. Exp Station Bulletin #433, See page: 117
  • Some Weedy Plants of North Carolina, 1955 North Carolina Ag. Ext. Circular # 390, See page: 34
  • S.W.S.S. Weed ID Guide, 1993 Section Number and Five letter code: 10 TOXRA
  • Weeds, 1955 (1980) Walter Conrad Muenscher, ISBN# 0-8014-1266-8 See page: 306
  • Weeds, A Golden Guide, 1972 ISBN#0-307-24353-2 See page: 82
  • Weeds of Arkansas 1981 (MP 169-5M-3-81) See page: 2
  • Weeds of Canada, 1970 Canada Dept. of Ag., Pub. # 948, See page: 117
  • Weeds of Kentucky and Adjacent States, 1991 (ISBN 0-8131-1743-7) See page: 92
  • Weeds of Nebraska and the Great Plains, 1994 (ISBN 0939870-00-4) See page: 45
  • Weeds of the Midwestern United States & Central Canada, University of Georgia 2010, ISBN#0-8203-3506-1 See page: 42
  • Weeds of the North Central States, 1981 Univ. of Illinois, Urbana - Champaign Bulletin # 772, See page: 121
  • Weeds of the Northeast, 1956, Univ. of Delaware Field Manual #1 See species #: 332
  • Weeds of the Northeast, 1997 Cornell University ISBN# 0-8014-8334-4 See page: 328, 340
  • Weeds of the Northern United States and Canada, 1964 Montgomery See page: 109
  • Weeds of the Northern U.S, and Canada, 1999 Royer and Dickinson, (ISBN# 1-55105-221-0) See page: 376, 378-79
  • Weeds of the South, University of Georgia 2009, ISBN#0-8203-3046-9 See page: 39
  • Weeds of the Southern United States, 1975, North Carolina Ag. Extension Circular #599 See page: 4
  • Weeds of the United States and Their Control, Lorenzi 1987, ISBN# 0-442-25884-4 See page: 201
  • Weeds of the West, 1992 (ISBN 0941570-13-4) See page: 14
  • Weeds of the West, 2000 (ISBN 0941570-13-4) See page: 14
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  • Wildly Successful Plants, A Handbook of North American Weeds, 1977 (ISBN# 0-02-528850-4) See page: 61,117,171
  • Listed as a `Weed` by the Biota of North America Program, 2008 x
  • Listed in the WSSA Composite List of Weeds X
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