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Sea Holly
Acanthus spp.

Holly-leaved Acanthus, Holly Mangrove, Jeruju Putih (Malay)


thicket of sea hollyThese plants have no relation whatsoever with the Christmas Holly, although they appear similar.

In fact, not all the leaves have the spiny edges that give them their common name. Leaves growing the deep shade can be totally spineless.

Unlike some mangrove plants, Sea Holly do not exclude salt at the root level. In fact, their sap is salty and excess salt is secreted through the leaves, to be removed by rain or wind. Sometimes, the salt can be seen as a white crystalline layer on the upper surface.
Mangrove and wetland wildlife at
Sungei Buloh Nature Park
Main features: A shrub that grows to 1.5 m tall.

Roots: May develop small prop roots

Leaves: Thick, shiny, waxy, may have prickly edges.

Flowers: In a cluster at the branch tip. The species A. ilicifolius has light violet flowers, while A. ebracteatus has white flowers.

Fruits: Shiny green pods in a cluster.

Status in Singapore: Rare. Found only in suitable habitats, mostly northern parts of the island.

World distribution: India to Polynesia and Australia.
flowers
fruits
Classification: Family Acanthaceae.
The plant produces a cluster of flowers that develop into pods. When the pods ripen, they explode to propel the seeds up to 2m away.

Sea Holly grows on mud near the hide tide mark, often on mud lobster mounds. It can grow equally well under trees and in open areas. But it grows especially well in areas with more freshwater input. The plant can sometimes cover large areas and form thickets, particularly in disturbed mangrove. They also grow along river banks.

Uses: In Indonesia, the entire plant is placed in rice sacks to keep the rice dry (i.e., acts as a desiccant).

Traditional medicinal uses: The leaves of A. ilicifolius are used to treat rheumatism, neuralgia and poison arrow wounds (Malaysia). It is widely believed among mangrove dwellers that chewing the leaves will protect against snake bite. The pounded seeds of A. ebracteatus are used to treat boils, the juice of leaves to prevent hair loss and the leaves themselves to ward off evil (Malay). Both species are also used to treat kidney stones. The whole plant is boiled in fresh water, and the patient drinks the solution instead of water, half a glass at a time, until the signs and symptoms disappear (Thailand). Water extracted from the bark is used to treat colds and skin allergies. Ground fresh bark is used as an antiseptic. Tea brewed from the leaves relieves pain and purifies the blood (widespread in both the Old and New World).

Role in the habitat: Forming the undergrowth in the back mangroves, Sea Holly provides shelter for small creatures, and food for those that manage to graze their thorny leaves.

LINKS

REFERENCES
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  • Ivan Polunin, "Plants and Flowers of Singapore", Times Editions, 1987 (p. 64: description, habitat, distribution, photo).
  • Peter K L Ng and N Sivasothi, "A Guide to the Mangroves of Singapore I: The Ecosystem and Plant Diversity", Singapore Science Centre, 1999 (p. 88-90: description, habit, photo, uses).
  • Colin Field, "Journey among Mangroves", International Society for Mangrove Ecosystems, 1995 (p. 70: medicinal use).
  • Michael Mastaller, "Mangroves: The Forgotten Forest Between Land and Sea", Tropical Press, 1997 (p. 97: medicinal uses).
 
By Ria Tan, 2001