Acanthus ilicifolius Care Guide
Acanthus ilicifolius is a salt-tolerant mangrove shrub with holly-like spiny leaves and blue flowers, used in brackish biotope displays.
Overview
Acanthus ilicifolius, the holly mangrove or sea holly, is a salt-tolerant mangrove shrub of the Indo-Pacific. It is recognised by rigid, holly-like leaves with spine-tipped lobes and by blue flowers borne in terminal spikes. It is used as a tall background plant in mangrove paludariums and brackish biotope displays.
Taxonomy
- Family: Acanthaceae
- Genus: Acanthus
- Scientific name: Acanthus ilicifolius
- Common synonyms: Holly Mangrove, Sea Holly
Habitat
The species is native to Southeast Asia, Indochina, Indonesia, the Philippines, southern China and northern Australia, growing in mangrove environments where freshwater meets the sea, typically just above the high-tide mark. It is an erect shrub reaching up to about 2 m tall, with leaf blades around 7.5-18.5 cm long bearing four to five spine-tipped lobes on each side. The species is classed Least Concern on the IUCN Red List. Two varieties are recognised: var. ilicifolius and var. integrifolius.
Tank requirements
- Placement: background, emersed growth
- Water type: brackish
- Temperature: 22-30 °C (72-86 °F)
- pH: 7.5-8.5
- GH: 10-25 °dGH
- Lighting: high
- CO2: not required
- Mature height: up to about 150 cm
Salt tolerance
Acanthus species are salt secretors: rather than excluding salt at the roots, the sap is salty and excess salt is excreted through the leaves, sometimes visible as a white crystalline film on the upper surface, later removed by rain or wind. This adaptation allows the plant to grow in higher-salinity environments.
Growth and propagation
This is a slow-growing shrub propagated by cuttings. Because of its size and brackish requirements it is rated as an advanced plant.