Family: Rubiaceae
Origin, Description & Uses
Richardia scabra (Mexican clover or Florida pusley) is native to tropical and subtropical regions of the Americas. It is a low-growing annual herb that spreads along the ground, often forming dense mats in lawns, gardens, pastures, and other disturbed areas. The plant produces small white to pinkish tubular flowers and has opposite leaves that allow it to quickly colonize open soil. It is not commonly cultivated for ornamental or agricultural use and is primarily recognized as a widespread weed in warm climates.
Risks & Threats
In Hawaiʻi, Richardia scabra is naturalized on Kauaʻi, Oʻahu, Molokaʻi, Maui, and Hawaiʻi Island. It possesses traits that are cause for concern, including rapid growth, abundant seed production, and strong tolerance for disturbance and poor soils. These characteristics allow it to spread aggressively in managed landscapes and disturbed habitats, where it can compete with and displace low-growing native vegetation. Its persistence in lawns, agricultural fields, and roadside environments increases maintenance demands and can contribute to reduced ecosystem quality over time. Because this species is naturalized across the Hawaiian Islands and can negatively impact tropical island ecosystems, selecting low-risk or native groundcover alternatives is strongly recommended when available. In areas where it is already established, efforts should focus on preventing further spread and avoiding intentional planting in new locations to minimize additional impacts.
High Risk Traits:
- Broad climate suitability
- Thrives in tropical climates
- Widely naturalized (including Hawaiian Islands of Kauai, Oahu, Maui and Molokai)
- A disturbance-adapted weed of lawns, gardens, and crops
- Other Richardia species are regarded as weeds
- Forms dense colonies that may exclude other vegetation
- Reproduces by seeds
- Annual, reaching maturity in one growing season
- Seeds dispersed by water, in soil, and possibly by other means
- Seeds form a persistent seed bank
Low Risk Traits:
- Unarmed (no spines, thorns, or burrs)
- Provides fodder for livestock and green manure
- May not thrived in shaded positions
- May be self-incompatible
- Herbicides reported to provide effective control
