Emergent and Marginal Plants for Paludariums and Ripariums
Paludariums and ripariums need plants for the waterline and humid air zone. Learn emersed and marginal plant groups, their requirements, and which terrestrial plants to avoid.
A paludarium is a vivarium that combines aquatic and terrestrial elements, with a waterline running through it; a riparium is the related setup where the land area is small and the focus is on the water margin. Both rely on emergent and marginal plants: plants grown with their roots wet and their foliage in humid air. Because most aquarium plants are amphibious, the planting palette is wide, but the choices and conditions differ from a fully submerged tank.
Emersed, marginal and bog plants
Nine out of ten tropical aquarium plants can survive both above and below the water surface, having evolved with seasonal water-level changes. Grown emersed, only the roots are in water or wet substrate while the leaves are in the air. Marginal and bog plants occupy the same niche in nature, thriving in very humid or wetland areas at the edge between land and water.
Suitable plant groups
- Amphibious aquarium plants grown emersed: Cryptocoryne, Anubias (hardy and easy), Bucephalandra, Echinodorus and Hygrophila
- Epiphytes mounted on the hardscape: Anubias, Bucephalandra, ferns and mosses
- Bog and marginal plants for the wet margin and humid land zone
- Bromeliads and other humidity-loving plants on the emergent structure
Requirements
- High humidity, maintained by an enclosed setup and regular misting
- Adequate light reaching the emergent foliage
- Root access to water or wet substrate at the margin
- Good drainage, commonly via a false bottom, so roots stay wet but not waterlogged in the land zone
The transition zone and avoiding melt
The most interesting planting is the transition zone right at the waterline, where emergent stems rise out of the water. Plants that came from an emersed nursery already have air-grown leaves and settle in quickly; plants moved from submerged to emersed (or the reverse) must convert their leaves and may shed old growth in the process. If conditions are poor this conversion can become widespread melting, so keep humidity and light stable while plants adjust.