Alocasia macrorrhizos (L.) G.Don

Etymology Genus Not Colocasia, but resembling in appearance
Species Big rhizomes
Family Araceae
Synonyms Arum macrorrhizon L., Colocasia macrorrhizos (L.) Schott
Common Names Elephant Ear Taro, Giant Taro, Greater Alocasia
Status Exotic: Naturalised
Form Herb
Native Distribution Philippines

Diagnostics:

This aroid is commonly found on the fringes of forests or abandoned open land. It can be stemless or with a short woody one. The leaves can grow to a very large size to a metre long (hence the common name Elephant Ear) and the leaf margins are always very wavy.

Colocasia esculenta, the Coco Yam is a similar species which is also commonly found in open areas. The leaves are greyish green and margins not as wavy in comparison. More distinctly, The V-shape at the leaf base does not reach the petiole, unlike A. macrorrhizos which does.


Interesting Facts:

The Elephant Eat Taro used to be cultivated formerly as an animal feed (Keng & Tan, 1998), but has since naturalised throughout Singapore. Its native distribution was obscure because it has already been distributed throughout tropical Asia as a subsistence crop during prehistoric times (Mayo, 2012).

Recent molecular studies revealed that it was likely to originate from Philippines (Nauheimer et al., 2012).The edible part are the rhizomes but they need to be boil or roasted to remove the calcium oxalate crystals. These are microscopic needle like crystals that can cause pain and swelling when ingested, and are the same constitutents in white sap of Dumb Cane (Dieffenbachia species).


A cultivated stand of Elephant Ear Taro in the Singapore Botanic Gardens.

The leaf have wavy margins. Note the V-shaped base touches the petiole.

A clump of Alocasia macrorrhizos at a forest edge.

The flower, being swamped by flies.

Aggregate fruits. Those from the top have already devoured by animals.


References

Keng H, SC Chin & HTW Tan. (1998) The Concise Flora of Singapore. Volume II: Monocotyledons. Singapore University Press, Singapore. 215 pp.
Mayo S. (2012) Alocasia macrorrhizos (elephant ear taro). Royal Botanic Gardens, Kew, London. http://www.kew.org. Accessed on 8-Jan-2012.
Nauheimer L, PC Boyce & SS Renner. (2012) Giant taro and its relatives: A phylogeny of the large genus Alocasia (Araceae) sheds light on Miocene floristic exchange in the Malesian region. Molecular Phylogenetics and Evolution, 63: 43-51.


Posted Date: 2013-01-09 / Modified Date: 2015-01-11