Euphorbia hyssopifolia (Chicken Grass)

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Euphorbia hyssopifolia is an annual herbaceous plant in the spurge family that grows about 2 feet tall. It reproduces by seed. 

Chicken grass is easily identified by its asymmetric leaves with reddish or purplish markings and small clusters of white to pink flowers.

Chicken Grass Classification

  • Domain: Eukaryota
  • Kingdom: Plantae
  • Phylum: Spermatophyta
  • Subphylum: Angiospermae
  • Class: Dicotyledonae
  • Order: Malpighiales
  • Family: Euphorbiaceae
  • Genus: Euphorbia
  • Species: Euphorbia hyssopifolia
  • Common Names: Hyssopleaf Sandmat, Hyssop Spurge, and Hyssopleaf Spurge

Nativity and Distribution

Chicken grass is native to the Southern United States and Central and South America. Today, it has been introduced in other continents and countries such as:

  • Australia
  • Asia
  • Africa

Physical Characteristics

The plant has smooth stems and serrated leaves with reddish to purplish markings
The plant has smooth stems and serrated leaves with reddish to purplish markings. Image: inaturalist/radhaveach
  • Leaves: Lop-sided, finely serrated, light to dark green with reddish to purplish markings
  • Fruits: Glabrous, three-capsuled
  • Stems: Smooth, erect, branched stems that contain a milky sap
  • Flowers: Cyathias in small loose clusters located in the leaf axils
  • Roots: Tap root system 

Euphorbia hyssopifolia is a herbaceous annual plant with semi-upright or spreading branches that grows 2 feet tall. 

It is easily identified by its asymmetric leaves with reddish or purplish markings and small clusters of white to pink flowers.

The leaves are arranged in pairs along the stem, oblong to linear-lanceolate, serrated, and 5-35 mm long and 2-15 mm wide. They are light to dark green on the upper surfaces with reddish or purplish markings and greyish green on the underside. In their initial growth, they may have sparse hairs but become hairless in maturity. 

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The stems are long, erect to ascending, branched, and green, yellowish, or reddish in color. They may have sparse to soft dense hairs and also contain a milky sap.

Chicken grass flowers are cyathias in small loose clusters, 0.8-1.5 mm long, white to pinkish, located in the leaf axils or at the tips of the branches. Flowering occurs in spring and summer.

The fruits are glabrous, 1-2 mm long and 1-2 mm wide, with 3-seed compartments. Seeds are ovoid, slightly wrinkled, black, 1 x 0.8 mm. 

Reproduction, Dispersal, and Life Cycle

  • Life Cycle: Annual
  • Seeds: Produces three seeds per plant
  • Climate: Tropical and subtropical climate 
  • Dispersal: Wind, water, and contaminated vehicles and produce

E. hyssopifolia behaves as an annual or as a short-lived perennial plant, thriving in warm climates. 

The weed reproduces by seeds. However, it is not a prolific seed producer and the seeds have little to no dormancy. 

To compensate for these limitations, the weed disperses the seeds close to the parent plants through water, wind, and contaminated vehicles and produce. 

Germination occurs between 7-14 days on the top layer of the soil with the rate significantly affected by poor light and soil depth. Due to its short life cycle, it flowers when young and spreads rapidly to colonize new areas. 

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Similar Plants

  • Euphorbia nutans
  • Euphorbia heterophylla
  • Euphorbia thymifolia
  • Euphorbia ophthalmica
  • Euphorbia hirta

Uses

  1. It is grown in ornamental gardens for its attractive foliage.
  2. Its milky sap is used as a natural pest deterrent in gardens.
  3. The plant was used as traditional medicine for respiratory, skin, and digestive problems.

Impact on Farms and Environment

Chicken grass is a common weed of agricultural areas, lawns, and sandy washes
Chicken grass is a common weed of agricultural areas, lawns, and sandy washes. Image: ncsu.edu/harryrose

Hyssop spurge thrives in loamy or sandy soils that are well-drained. Hence it is a common weed in agricultural areas, lawns, along streambeds, and sandy desert washes. 

Its short life cycle necessitates fast growth and can quickly encroach on large patches of land if left unchecked. 

Control

  • Mechanical control: Hand-pull or dig out the young plants
  • Chemical control: Apply preemergence herbicides like picloram and clopyralid

Hand-pulling or digging out the plants when young can help reduce seed production and spread of the weed. It is a viable option, however, when the infestation is small and conducted efficiently. 

For larger infestations, apply pre-emergent broadleaf herbicides like picloram, clopyralid, or a diuron + hexazinone + sulfometuron-methyl depending on the infested area for effective control against Euphorbia hyssopifolia.