Weed Information: Larrea tridentata (creosotebush)
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Larrea tridentata (creosotebush)

Family: Zygophyllaceae

Description

This aromatic shrub has opposite, hairless leaves and yellow flowers. It is native to arid areas in the southwestern United States. The plants are often very uniformly spaced, giving the effect of having been planted.

Characteristics

Flower Color
  • Yellow
Inflorescence Type (How the flowers are arranged on the plant)
  • Solitary, axillary
Number of Petals
  • 5 petals
Petal Separation
  • Completely free to base
Petal Tip
  • Rounded
Flower Symmetry
  • Flowers regular
Flower Length (Head length in the Asteraceae)
  • 2 mm (.08 inch)
  • 3 mm (.12 inch)
  • 4 mm (.16 inch)
  • 5 mm (.20 inch)
  • 6 mm (.24 inch)
Flower Width (Head width in the Asteraceae)
  • 1.0 cm (.40 inch)
  • 1.5 cm (.60 inch)
  • 2.0 cm (.80 inch)
Number of Sepals
  • 5 sepals
Sepal Separation
  • Completely free to base
  • United at base < 25% length
Sepal Tip
  • Pointed
Flower Sex
  • Bisexual (perfect)
Number of Styles
  • 4 styles
  • 5 styles
Number of Stamens
  • 5 stamens
  • 6 stamens
  • 7 stamens
  • 8 stamens
  • 9 stamens
  • 10 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
  • 4 carpels
  • 5 carpels
Ovary Position
  • Superior (hypogynous)
Fruit Type
  • Capsule, > 3-celled
Fruit Length at Maturity
  • 4 mm (.16 inch)
  • 5 mm (.20 inch)
Fruit Width at Maturity
  • 4 mm (.16 inch)
  • 5 mm (.20 inch)
Burs
  • Fruit or seed NOT bur-like

Leaf Arrangement
  • Opposite
Leaf Type
  • Bifoliolate (2 leaflets)
Stipules
  • Foliaceous < 2 mm (< .08 inch) long
Tendrils
  • Tendrils absent
Venation
  • Palmate
  • Pinnate
Petiole (leaf stem) Blade Ratio
  • Petiole absent (leaf sessile)
Leaf Length (blade PLUS petiole)
  • < 5 mm (< .20 inch)
  • 5 - 10 mm (.20 - .40 inch)
  • 1 - 2 cm (.40 - .80 inch)
Leaf Width
  • 1 - 5 mm (.04 - .20 inch)
  • 5 - 10 mm (.20 - .40 inch)
Succulence
  • Succulent
  • Not succulent
Leaf or Leaflet Margin
  • Entire
Leaf or Leaflet Blade Base
  • Rounded
Leaf or Leaflet Tip
  • Acuminate (attenuate)
  • Acute
  • Rounded (obtuse)
Leaf or Leaflet Blade Surface
  • Glabrous (NO hairs)

Milky Juice
  • Juice NOT milky (watery)
Woodiness
  • Woody
Spines or Thorns
  • Spines or Thorns ABSENT
Aromatic (vegetative structures)
  • Aromatic
Life Cycle
  • Perennial
Growth Habit (while flowering)
  • Erect, spherical (bushy)
Plant Height at Maturity
  • 1 - 1.5 meters (3.3 - 5.0 feet)
  • 1.5 - 2.0 meters (5.0 - 6.6 feet)
  • 2 - 2.5 meters (6.6 - 8.3 feet)
  • 2.5 - 5 meters (8.3 - 16.6 feet)
Wind Dissemination
  • Not wind disseminated
Moisture Regime
  • Arid
Chlorophyll
  • Present

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

Root or Vegetative Propagule
  • Fibrous
  • Tap Root

US State
  • Arizona
  • California
  • New Mexico
  • Nevada
  • Utah

  • Weeds of California, 1970, State of California Publications and Documents. See page: 287
  • Weeds of the West, 1992 (ISBN 0941570-13-4) See page: 596
  • Weeds of the West, 2000 (ISBN 0941570-13-4) See page: 592
  • 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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