Family: Asteraceae
An invasive forb that is quickly establishing in Hawaiʻi. Native to the dry areas of the Southwest USA and Mexico, Porophyllum ruderale is ‘at home’ on the dry sides of the state. Quickly spreading along the roads and lava fields, dense thickets on the Kona side of Hawaiʻi Island are common. It thrives in rocky-dry areas and disturbed places. The self-seeding, wind-dispersed forb is a garden weed and is classified as an agricultural weed in California. A popular herb in Mexico and South America, it has a distinctive smell and taste. Some say it’s a cross between cilantro and rue with citrus notes, a taste that some find disgusting.
Description and Dispersal:
- Sparsely branched, erect forb grows up to 5 feet tall
- Alternately arranged leaves are more purple than green
- Leaves are elongated with somewhat scalloped edges
- Glands are visible on leaves and flowers
- Flower heads are few to many with insignificant disk flowers-not showy
- Fruit is an achene
High Risk Traits:
- Elevation range exceeds 1000 m, demonstrating environmental versatility
- Thrives in tropical climates
- Potentially naturalizing on Hawaii Island; naturalized in the Galapagos
- A weedy species of disturbed sites and of several agricultural crops (although impacts to crops generally unspecified)
- Tolerates many soil types
- Able to form thickets in native range
- Reproduces by seed
- An annual, capable of reaching maturity in one growing season
- Seeds dispersed by wind, people and possibly other vectors
- Missing ecological information limits accuracy of risk prediction
Low Risk Traits:
- Despite weedines, evidence of serious negative impacts is lacking
- Unarmed (no spines, thorns or burrs)
- Palatable to browsing and grazing animals
- Non-toxic
- Edible and medicinal uses
- Not reported to spread vegetatively