Ranalisma Rostratum

Quick facts

Identity

Also known as

Ridley's swordplant

Synonyms

Ranalisma rostrata; Echinodorus ridleyi

Environment

Freshwater

Native to

Thailand, Malaysia, Indonesia, tropical Asia

Habitat

Rice paddies, swampy margins, and shallow edges of slow-moving water bodies in tropical Asia

Sourcing

Aquacultured

Conservation

Not Evaluated

Care

Care level

Moderate

Growth form

Carpeting

Max height

2 – 3 in (5.1 – 7.6 cm)

Growth rate

Fast

Placement

Foreground, Carpet

Water

Temperature

68 – 82 °F (20 – 28 °C)

pH

5.0 – 7.5

dKH

0 – 14 dKH

PAR

40 – 80 PAR

Flow

Low-Moderate

Light

High

CO₂

Required

Planting

Substrate

Nutrient-rich required

Feeds from

Both

Fertilizer needs

High

Colors

Green

Feeding & breeding

Propagation

Runners

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Care guide

Overview

Grown in the rice paddies and shallow, slow-flowing margins of tropical Asia, this species produces narrow, grass-like blades underwater that spread by runners into a dense green foreground mat 1.5-2.5 inches tall. It demands high light, injected CO2, and a nutrient-rich substrate to stay compact rather than stretching into its taller, paler emersed form.

Care

Ranalisma rostratum needs a steady combination of strong lighting, injected CO2, and a nutrient-rich substrate to stay compact and grass-like underwater; without these it stretches out and takes on paler, lanceolate leaves closer to its emersed form. It resembles Helanthium tenellum but stays narrower-leaved and lower, forming a dense mat around 1.5-2.5 inches tall once established. Keep it away from taller plants that would shade it, since it needs a well-lit spot at the front of the tank to hold its compact carpet form.

Planting & trimming

Plant individual rosettes into the substrate a short distance apart rather than as a dense clump, since the runners will fill in the gaps over time. Once established, thin out overly dense patches and trim or remove excess runners to keep the carpet from becoming congested. It can also be grown emersed in paludariums or wabi-kusa setups, where it forms a compact rosette of spoon-shaped leaves.

Fertilizing

Regular dosing of liquid macro and micronutrients supports steady growth, and root tabs pushed into the substrate near the rosettes help fuel runner production. Iron deficiency shows up quickly as pale yellow new growth, so a supplement containing chelated iron is worth adding if leaves start losing their green color. A nutrient-dense aquasoil substrate reduces the need for heavy water column dosing but does not eliminate it entirely.

Propagation

The plant spreads through runners (stolons) that are technically modified inflorescences, sending out plantlets that root into the substrate nearby. New plantlets can be left attached to form a spreading mat or separated with a few leaves and roots and replanted elsewhere. Growth accelerates under strong light and CO2, producing runners at a faster rate.

Problems

Pale, yellowing new leaves point to iron or micronutrient deficiency rather than disease, and is usually corrected with more frequent fertilizer dosing. Insufficient light causes the plant to lose its tight carpet habit and grow taller, thinner leaves similar to its land form. It is not particularly prone to melt after planting, but plant-grazing fish and snails can shred the thin blades and slow carpet formation.

Sources

1. Ranalisma rostratum | Aquasabi - Aquascaping Shop
2. Ranalisma rostratum Aquatic Plant Care | Atlarium
3. Ranalisma rostratum - Flowgrow Aquatic Plant Database
4. Ranalisma rostrata

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