Weed Information: Asclepias latifolia (milkweed, broadleaf)
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Asclepias latifolia (milkweed, broadleaf)

Family: Asclepiadaceae

Description

The specific epithet `latifolia` means `broad leaved` and this is the broadest leaved of the North American milkweed species. The leaves are seldom more than 1.5 times as long as broad. The flowers are yellow to green and occur in simple umbels from the upper leaf axils. This species is quite toxic to livestock and occurs in patches in the dry soils of the southwest.

Characteristics

Flower Color
  • Yellow
  • Yellow-green
  • Green
Inflorescence Type (How the flowers are arranged on the plant)
  • Axillary umbel
  • Simple umbel
Number of Petals
  • 5 petals
Petal Separation
  • United at base only (<25% length)
  • United from 25% - 75% length
Petal Tip
  • Pointed
  • Rounded
Flower Symmetry
  • Flowers regular
Flower Length (Head length in the Asteraceae)
  • 1.0 cm (.40 inch)
  • 1.5 cm (.6 inch)
  • 2.0 cm (.8 inch)
Flower Width (Head width in the Asteraceae)
  • 6 mm (.24 inch)
  • 7 mm (.28 inch)
  • 8 mm (.32 inch)
  • 9 mm (.36 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
  • 1 style
Number of Stamens
  • 5 stamens
Stamens Attached to the Petals
  • Stamens attached to the petals
Stamens Connate (united)
  • Filaments united, monodelphous

Carpel Separation
  • Carpels united (or one)
  • Carpels separated
Number of Carpels
  • 2 carpels
Ovary Position
  • Superior (hypogynous)
Fruit Type
  • Follicle
Fruit Length at Maturity
  • 6.0 cm (2.4 inches)
  • 7.0 cm (2.8 inches)
  • 8.0 cm (3.2 inches)
  • 9.0 cm (3.6 inches)
Fruit Width at Maturity
  • 1.5 cm (.60 inch)
  • 2.0 cm (.80 inch)
  • 2.5 cm (1.0 inch)
  • 3.0 cm (1.2 inches)
  • 3.5 cm (1.4 inches)
Burs
  • Fruit or seed NOT bur-like

Leaf Arrangement
  • Opposite
Leaf Type
  • Simple (including lobed leaves)
Stipules
  • Lacking
Tendrils
  • Tendrils absent
Venation
  • Pinnate
Petiole (leaf stem) Blade Ratio
  • Petiole absent (leaf sessile)
  • Petiole < 25% total length
Leaf Length (blade PLUS petiole)
  • 4 - 10 cm (1.60 - 4.0 inches)
  • 1 - 2 dm (4.0 - 8.0 inches)
Leaf Width
  • 4 - 10 cm (1.6 - 4.0 inches)
  • 1 - 2 dm (4.0 - 8.0 inches)
Leaf Shape (simple leaves only)
  • Obovate
  • Orbicular (round)
  • Oval
Succulence
  • Succulent
  • Not succulent
Leaf or Leaflet Margin
  • Entire
  • Undulate (sinuate, repand)
Leaf or Leaflet Blade Base
  • Cordate
  • Rounded
Leaf or Leaflet Tip
  • Notched (emarginate, retuse)
  • Mucronate
  • Rounded (obtuse)
Leaf or Leaflet Blade Surface
  • Glabrous (NO hairs)
  • Tomentose

Milky Juice
  • Juice milky
Woodiness
  • Herbaceous
Spines or Thorns
  • Spines or Thorns ABSENT
Aromatic (vegetative structures)
  • Not aromatic
Life Cycle
  • Perennial
Growth Habit (while flowering)
  • Erect, columnar (narrow)
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)
Wind Dissemination
  • Fruit, seed, or spore wind borne
Moisture Regime
  • Arid
Chlorophyll
  • Present

Stem Cross Section
  • Hollow (flowering stem at maturity)
  • Round
Flowering Stem Leaves
  • Stem uniformly leafy
Main Stem Branches
  • Main stem unbranched
  • Main stem branched

Root or Vegetative Propagule
  • Rhizomatous

US State
  • Kansas
  • Texas
  • Arizona
  • California
  • Colorado
  • New Mexico
  • Oklahoma
  • South Dakota
  • Utah
  • Nebraska

  • An Illustrated Guide To Arizona Weeds, 1972 (ISBN 0-8165-0288-9) 338 pages. See page: 226
  • 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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