Glossostigma cleistanthum
A self-pollinating aquatic plant native to four continents.
Glossostigma cleistanthum, commonly called mudmat, is a freshwater aquatic plant found naturally in Australia, New Zealand, India, and East Africa. It belongs to the family Phrymaceae, which includes both annual and perennial species. Mudmat is a cleistogamous plant, meaning it can self-pollinate through flowers that never open.
In the littoral zone—the shallow area near the shore of lakes, rivers, or seas—mudmat grows on muddy substrate. It prefers oligotrophic conditions, meaning clear water with low nutrient levels. The plant can live both submerged and emergent. When fully underwater, its leaves are nearly stalkless and grow in alternating pairs that resemble rabbit ears, reaching 0.5 to 2.5 inches long. These submerged leaves bear closed, self-pollinating flowers. When water levels drop and the plant becomes emergent, its leaves shrink to just 0.2 to 0.5 inches, and it produces open, insect-pollinated flowers on short stalks. The emergent parts of the plant are annuals and die back in winter, while the submerged parts are perennials that stay green and continue flowering through the cold season.
Outside its native range, mudmat is considered invasive. In North America, it was first recorded in 1992 at Hamburg Cove, Connecticut, and now causes problems in Rhode Island, New Jersey, and eastern Pennsylvania. It grows quickly and can reach densities of up to 25,000 plants per square meter. Because of its small size, it is not expected to interfere with recreational boating or other lake activities. However, it is a concern because it appears in areas that host endangered species, including *Eriocaulon parkeri*, *Crassula aquatica*, *Lilaeopsis chinensis*, *Limosella subulata*, *Myriophyllum tenellum*, and *Heteranthera multiflora*. How mudmat first arrived in the United States is unclear, but it may have been introduced with aquarium plants. Its spread is likely aided by migrating waterfowl, watershed connections, and boating or fishing activities.
Quick Facts
- Genus
- Glossostigma
- Species
- cleistanthum
Facts from the source article.
Lore & Background
Mudmat is a freshwater aquatic species that grows on muddy substrate in the littoral zone, the area close to the shore in a lake, sea, or river. It prefers oligotrophic conditions, meaning high water clarity and low nutrients. When submerged, its leaves are between 0.5–2.5 inches long and bear closed, self-pollinating flowers; these leaves are nearly sessile and grow along the stem in alternating pairs that resemble rabbit ears. When water recedes and growth is emergent, the leaves are much smaller, ranging between 0.2–0.5 inches in length, and the plants produce insect-pollinated flowers on short stalks.
Reader's Guide
Glossostigma cleistanthum is significant as an invasive species outside its native range, currently causing problems in Rhode Island, New Jersey, and Eastern Pennsylvania. The earliest record of mudmat in North America was in 1992 in Hamburg Cove, CT. There is concern for it as an invasive species since it occurs in areas with species listed as endangered in Connecticut and/or New Jersey, including Eriocaulon parkeri, Crassula aquatica, Lilaeopsis chinensis, Limosella subulata, Myriophyllum tenellum, and Heteranthera multiflora. It grows quickly and, due to its small size, is not expected to interfere with recreational boating or other forms of recreational lake use. In some areas it can reach densities as large as 25,000 plants per square meter. Although it is unclear how G. cleistanthum was originally introduced to the United States, one possibility is that it was introduced along with aquarium plants. Subsequent dispersal is expected to be due to migrating waterfowl, watersheds, boating, and fishing activities.
Did You Know?
- Submerged portions of the plant are perennials that stay green through winter, while emergent portions are annuals that die in winter.
- It can reach densities as high as 25,000 plants per square meter in some areas.
Frequently Asked Questions
What is Glossostigma cleistanthum?
Mudmat is a small freshwater aquatic plant in the Phrymaceae family that grows in shallow, nutrient-poor waters. It can survive both fully submerged and above the waterline, making it a versatile littoral-zone species.
Where is Glossostigma cleistanthum naturally found?
Its native range spans Australia, New Zealand, India, and East Africa. It typically roots itself in muddy substrate along the shallow edges of lakes and rivers.
How does Glossostigma cleistanthum reproduce?
It is a cleistogamous species, meaning its flowers never actually open; instead, the plant self-pollinates internally. This lets it set seed without relying on pollinators such as bees or wind.
What growing conditions does mudmat prefer?
It thrives in oligotrophic, clear-water environments in the littoral zone where nutrient levels are low. Submerged leaves range from about 0.5 to 2.5 inches long, while emergent leaves are smaller at roughly 0.2 to 0.5 inches.
How dense can a mudmat mat become, and when did it first show up in North America?
Under ideal conditions a single square meter of substrate can hold up to 25,000 individual plants packed tightly together. The earliest confirmed North American record dates to 1992 at Hamburg Cove in Connecticut.
More in Aquarium and Aquatic Plants, Part 2 1-24
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