Family: Phrymaceae

Origin, Description & Uses
Glossostigma diandrum, commonly known as mudmat, is a small, creeping aquatic plant native to Australia and New Zealand. It forms low, dense mats of tiny, bright green leaves that spread rapidly across wet soils or submerged surfaces. This species is especially popular in the aquarium and aquascaping trade, where it is valued for its ability to create a lush, carpet-like foreground under high light and nutrient-rich conditions. Mudmat can grow both fully submerged and in moist, emergent environments, making it adaptable to a range of freshwater habitats.

Risks & Threats
Although Glossostigma diandrum is not currently known to be naturalized in the Hawaiian Islands, it possesses traits that are cause for concern. Its rapid growth, mat-forming habit, and ability to reproduce vegetatively allow it to spread quickly and outcompete native aquatic and wetland plants. If introduced into natural waterways or wetlands, it could alter habitat structure, reduce biodiversity, and interfere with water flow. These characteristics could detrimentally impact tropical island ecosystems, where native species are often highly specialized and vulnerable to competition. Care should be taken to prevent its release into the environment, and safer, non-invasive alternatives are recommended for aquarium use.

High Risk Traits:

• Broad climate suitability
  
• Native or naturalized in tropical/subtropical climates
  
• History of repeated introductions outside native range
  
• Naturalized beyond native range
  
• Congeneric weed
  
• Forms dense thickets
  
• Aquatic
  
• Produces viable seed
  
• Self-compatible or apomictic
  
• Reproduces by vegetative fragmentation
  
• Propagules dispersed intentionally by people
  
• Propagules adapted to wind dispersal
  
• Propagules water dispersed
  
• Tolerates mutilation, cultivation, or fire

Low Risk Traits:

• No spines, thorns, or burrs
  
• Not allelopathic, parasitic, toxic, or allergenic
  
• No fire hazard
  
• Not shade tolerant
  
• No unintentional dispersal (contaminants, animals, gut passage)
  
• Not a prolific seed producer