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(Glossostigma cleistanthum)

Photo of mudmat
Photo credit: Leslie J Mehrhoff, University of Connecticut,

A tiny fast-growing aquatic plant that can tolerate a wide range of conditions. It is commonly grown in the aquarium trade and could pose a threat to natural areas if released.


This plant has been misidentified in other regions as Glossostigma diandrum and has not been extensively searched for outside the northeastern United States. It may be underreported.

Ecological threats:
  • Reported as a very fast rate of growth, and likely to survive cold winters.
  • Probably introduced to the US as an aquarium plant, then released into natural environments. It could be easily spread by waterfowl.
  • Unlike many other wetland or aquatic invasive plants, mudmat has been shown to be able to invade undisturbed, natural environments.
 Overview map of prohibited classification in WI
Prohibited (red) counties

Classification in Wisconsin: Prohibited

Species Assessment Groups (SAG) were assembled to recommend a legal classification for each species considered for NR 40. The recommendation for mudmat was based upon this literature review [PDF] developed by the department.


Leaves: Extremely tiny, bright green leaves grow no larger than 1-2 cm. They are linear based with broader tips.

Flowers: If submerged, tiny, cleistogamous (self-contained/pollinating) flowers are produced, but if stems are emergent, the plants produce tiny, white, open flowers.

Fruits & seeds: Small capsules are produced that carry seeds. Due to its dense growing habit, thousands of seeds can be produced from one square meter of plants.

Stems: Creeping stems grow horizontally just below the soil surface and root at the nodes.

Similar species: This plant might be confused with other tiny aquatic creeping plants, particularly in the Limosella or Utricularia families.


Currently, there have been no reports of mudmat in Wisconsin Have you seen it? Send us a report.


Mechanical: Little is documented with regards to controlling this plant. It can spread from fragments so care must be taken to collect and destroy all parts of the plant if pulled.

Chemical: Registered aquatic herbicides might provide some control, though little information is documented. Application of aquatic herbicide requires a permit.


View mudmat pictures in our photo gallery!


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