Family: Urticaceae
Phenax hirtus (phenax) is a shrub native to South America, Central America, the Caribbean and Mexico. Its uses are not well known. It was first reported as naturalizing on the Kona side of Hawaiʻi Island near the Makaula-O’oma State Forest Reserve in 2017. This plant can be easily mistaken for the native plant māmaki being they are both in the nettle family. However, generally māmaki can be distinguished by their red petiole and veins. Māmaki also has a white fleshy fruit whereas phenax produces a brown dry ball. This plant poses much risk as it grows well near areas that contain endangered plants, such as the endangered Hawaiian tree Flueggea neowawraea. It creates dense thickets and is shade tolerant, both of which make it a bad competitor in native Hawaiian forests.
High Risk Traits:
- Elevation range exceeds 1000 m, demonstrating environmental versatility
- Thrives in tropical climates
- Naturalized on Hawaii Island (first global record of naturalization)
- A pioneer plant of secondary vegetation (attributes of many other weedy species)
- Occurs near and could threaten the endangered Hawaiian tree Flueggea neowawraea W.J. Hayden
- Phenax sonneratii reported to be a crop weed of bananas, orchards and plantations
- Shade tolerant
- Forms dense thickets on Hawaii island
- Reproduces by achenes
- Unspecialized fruit (achenes) dispersed by wind, and probably water based on frequent occurrence in riparian habitats
- Gaps in biological and ecological information reduce accuracy of risk prediction
Low Risk Traits:
- Unarmed (no stinging hairs)
- May be somewhat palatable to browsing and grazing animals
- Non-toxic
- A plant of wet habitats (unlikely to threaten arid regions of islands)
