Glosso

Botanical name: Glossostigma elatinoides
Synonyms: Tricholoma elatinoides
Common name(s): Glosso

About:
A tiny creeping wetland and aquatic herb that forms dense, bright green carpets over mud and shallow-water substrates. Glossostigma elatinoides is one of New Zealand’s smallest native aquatic flowering plants and is also well known internationally as an aquarium foreground plant. Its slender branching stems root readily as they spread, producing small spoon-shaped leaves and minute white flowers.

Natural habitat:
Occurs in shallow freshwater and wet ground from coastal to lowland environments. Typical habitats include lake and pond margins, shallow pools, lagoons, slow-moving waterways, swampy ground and seasonally inundated mud. Plants may grow exposed on saturated substrates or completely submerged beneath shallow water.

Growing environment:
Wet, Sun, Shallow Water & Submerged tolerant. Best in permanently moist to inundated substrates with abundant light. It can grow both submerged and emergent, although low light encourages elongated, more upright growth rather than its characteristic compact carpet.

Endemic distribution:
Indigenous but not endemic to New Zealand. Recorded from the North Island, South Island and Stewart Island/Rakiura. Also indigenous to Australia and Tasmania.

Height:
Usually approximately 2–3 cm when growing as a compact carpet, although stems and leaves may elongate considerably under shaded or submerged conditions.

Width:
Individual creeping colonies may spread to approximately 15 cm or more across and can merge to form extensive mats under favourable conditions.

Flowering:
October – March
Produces extremely small white flowers approximately 2.5–3.5 mm across. Flowers arise close to the creeping stems and may be inconspicuous amongst the foliage.

Fruiting:
October – March
Produces small ovoid to globose capsules containing numerous minute seeds. Seeds may be dispersed by water, wind and ballistic projection.

Uses:
• Native freshwater and wetland planting
• Pond and shallow-water margins
• Native aquatic displays
• Aquarium foreground planting
• Paludariums and planted aquaria
• Mudflat and seasonally inundated habitat restoration
• Small-scale wetland habitat creation

Appearance:
Growth habit:
A minute creeping, mat-forming perennial herb with slender branching stems. Stems spread horizontally across wet substrates and root at the nodes, allowing plants to develop dense carpets. Branch tips may become slightly ascending.

Leaves:
Leaves are opposite, approximately 3–7 mm long and narrow-spathulate to narrow-obovate. They are bright green, thin and entire, with rounded or blunt tips. Each leaf gradually narrows into a petiole that may be approximately as long as the blade and can elongate during fruit development.

Flowers:
Flowers are minute, approximately 2.5–3.5 mm across and white. The corolla has two upper and three slightly larger lower lobes and may be finely hairy or almost hairless, with somewhat ciliate margins. The conspicuous tongue-shaped stigma is characteristic of the genus.

Fruit:
The fruit is a small, rounded to ovoid capsule containing minute seeds. Seeds are capable of dispersal through water as well as wind and ballistic projection.

Ecology:
An obligate wetland species that is almost always associated with saturated or inundated environments. Its creeping habit enables it to rapidly occupy exposed mud and very shallow freshwater habitats when conditions are favourable. Plants can tolerate complete submergence, providing low-growing vegetation within the shallow aquatic zone.

Associated habitats:
Freshwater wetlands, shallow lakes, ponds, lagoons, swamp margins, stream edges, temporary pools, saturated mudflats and seasonally flooded depressions. It occurs from coastal environments into lowland freshwater systems.

How to grow:
Best grown in consistently wet soil, saturated mud or shallow freshwater in a sunny position. For terrestrial or pond-margin cultivation, never allow the substrate to dry completely. It can also be grown fully submerged in aquaria, where strong light encourages its characteristic low, creeping growth.

In aquariums, planting small separated pieces a few centimetres apart encourages them to spread together into a continuous carpet. Insufficient light tends to produce taller, more upright growth. Added carbon dioxide and favourable water conditions can significantly increase growth rates.

Propagation:
Readily propagated vegetatively by separating rooted sections of the creeping stems and replanting them into wet substrate. Each section should include several healthy leaves and rooted nodes. It can also be propagated from seed, although division of established carpets is generally the simplest method in cultivation.

Cultural use:
No specific traditional Māori uses are widely documented for Glossostigma elatinoides. Its significance today is primarily ecological and horticultural as a component of New Zealand’s indigenous freshwater and wetland flora.

Garden value:
A fascinating miniature native for specialist wetland gardens, pond margins, shallow water features and planted aquaria. Its ability to create extremely low, vivid green carpets gives it considerable ornamental value, particularly where a naturalistic freshwater foreground is desired. Its international popularity as an aquarium plant also makes it an unusual example of a New Zealand indigenous species that has become widely recognised in aquatic horticulture.