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Asclepias oenotheroides (Zizotes milkweed)
Richardson, Charmaine

Asclepias oenotheroides

Asclepias oenotheroides Cham. & Schltdl.

Zizotes Milkweed, Hierba De Zizotes, Side-cluster Milkweed, Longhorn Milkweed, Primrose Milkweed, Lindheimer's Milkweed

Asclepiadaceae (Milkweed Family)

Synonym(s): Asclepias brevicornu

USDA Symbol: asoe

USDA Native Status: L48 (N)

The flower of this species is unique among milkweeds. The long, slender hoods extend beyond the stigmatic groove and flare or bow outward at the top. This species survives periodic droughts and occasional mowing even though it has shallow roots. It leafs out and flowers if rains follow a dry period. Plants tend to be scattered and populations appear to have a low density. One of the least conspicuous milkweeds (Webref 20).

Also known as zizotes from “hierba de zizotes”, the Spanish common name for this plant. This species was sometimes used by Native Americans to make a poultice for skin rashes (Webref 20).


From the Image Gallery

43 photo(s) available in the Image Gallery

Plant Characteristics

Duration: Perennial
Habit: Herb
Root Type: Tap
Leaf Retention: Deciduous
Leaf Arrangement: Opposite
Leaf Shape: Ovate
Breeding System: Flowers Bisexual
Inflorescence: Umbel
Fruit Type: Follicle
Size Notes: Up to about 16 inches tall.
Leaf: Leaf arrangement is opposite or sub-opposite. Leaf attachment is petiolate with 1/2 -1 in (1-2 1/2 cm) long petioles. Leaves ovate, 1-4 in (2 1/2-10 cm) long and 1/2-2 1/2 in (1-6 cm) wide. Wavy edges.
Flower: Green with purple tinges. Erect umbels, one to several per stem with 15 +/- flowers per umbel. Corolla reflexes backwards. Horns protrude through the hoods. Corolla is a lighter shade of green compared to the hoods.
Fruit: Pods often grow in pairs, length up to 3 1/2 in (9 cm) by 1 1/2 in (4 cm) wide.

Bloom Information

Bloom Color: Green
Bloom Time: Mar , Apr , May , Jun , Jul , Aug , Sep , Oct


USA: CO , LA , NM , OK , TX
Native Habitat: Sandy or gravelly ground, prairies, ditches and fields. Can be poisonous to livestock. Prefers sandy, dry soil.

Growing Conditions

Light Requirement: Sun
Soil Moisture: Dry
Conditions Comments: This member of the Milkweed family loves full sun and tolerates sandy, dry soils. Great for butterfly gardens. Purple tinge comes to upper leaves in full sun.


Use Wildlife: A well-documented larval host for Monarch butterflies.
Warning: All plants in the genus Asclepias are probably somewhat toxic, some fatally so, to both humans and other animals. The sap of some, including Asclepias oenotheroides, causes skin irritation in humans. The word zizotes in this plant's common name is a Spanish term meaning skin sores. Sensitivity to a toxin varies with a person’s age, weight, physical condition, and individual susceptibility. Children are most vulnerable because of their curiosity and small size. Toxicity can vary in a plant according to season, the plant’s different parts, and its stage of growth; and plants can absorb toxic substances, such as herbicides, pesticides, and pollutants from the water, air, and soil.
Conspicuous Flowers: yes
Fragrant Flowers: yes
Attracts: Butterflies
Larval Host: Monarch butterfly
Nectar Source: yes
Deer Resistant: High

Value to Beneficial Insects

Special Value to Native Bees
Special Value to Bumble Bees
Special Value to Honey Bees
Supports Conservation Biological Control

This information was provided by the Pollinator Program at The Xerces Society for Invertebrate Conservation.


Propagation Material: Seeds
Seed Collection: July-August
Seed Treatment: Soak seed overnight then cold moist stratify in the refrigerator for 14-30 days.

National Wetland Indicator Status

This information is derived from the U.S. Army Corps of Engineers National Wetland Plant List, Version 3.1 (Lichvar, R.W. 2013. The National Wetland Plant List: 2013 wetland ratings. Phytoneuron 2013-49: 1-241). Click here for map of regions.

From the National Organizations Directory

According to the species list provided by Affiliate Organizations, this plant is on display at the following locations:

Naval Air Station Kingsville - Kingsville, TX
Lady Bird Johnson Wildflower Center - Austin, TX
Sibley Nature Center - Midland, TX
Brackenridge Field Laboratory - Austin, TX
Stengl Biological Research Station - Smithville, TX
NPSOT - Austin Chapter - Austin, TX
National Butterfly Center - Mission, TX
NPSOT - Williamson County Chapter - Georgetown, TX

Herbarium Specimen(s)

NPSOT 0259 Collected Aug. 16, 1992 in Comal County by Mary Beth White
NPSOT 0126 Collected Sept. 7, 1991 in Bexar County by Lottie Millsaps
NPSOT 0182 Collected Oct. 8, 1991 in Bexar County by Lottie Millsaps

3 specimen(s) available in the Digital Herbarium

Wildflower Center Seed Bank

LBJWC-1790 Collected 2015-10-11 in Guadalupe County by Lady Bird Johnson Wildflower Center
LBJWC-1766 Collected 2015-08-03 in Travis County by Lady Bird Johnson Wildflower Center
LBJWC-1748 Collected 2015-07-21 in Hays County by Lady Bird Johnson Wildflower Center
LBJWC-1782 Collected 2015-09-17 in Caldwell County by Lady Bird Johnson Wildflower Center

4 collection(s) available in the Wildflower Center Seed Bank

Web Reference

Webref 20 - Milkweed Profiles (0) Monarch Watch

Additional resources

USDA: Find Asclepias oenotheroides in USDA Plants
FNA: Find Asclepias oenotheroides in the Flora of North America (if available)
Google: Search Google for Asclepias oenotheroides


Record Modified: 2019-01-17
Research By: NPC, RLU, GDG

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