Alocasia macrorrhizos ('elephant ear')
 | |
 | |
Plant uprooted to show the thick, above-ground stem. Photo courtesy Peter Sander, Papa Aroha Holiday Park, Coromandel (2005) |
In northern New Zealand, it is quite common to see Alocasia macrorrhizos (usually known as 'elephant ear') growing as an ornamental in home gardens, or as a weed in or next to ditches, streams, and wet paddocks or gullies.
All Alocasia species are naturally very poisonous and should not be eaten. A cultivated non-acrid variety is known in Tonga, and can be found in some Auckland vegetable markets, but do not imagine that the ornamental and wild plants can be eaten. Even after long cooking they remain very poisonous.
Other Alocasia species present in New Zealand may include A. brisbanensis (an Australian, Queensland species very similar to A. macrorrhizos). In fact, there may be some confusion about the actual identity of what has been recorded as A. macrorrhizos in New Zealand, and the identification should be investigated further (a good student project?!). The genus Alocasia is closely related to Colocasia, and the greatest diversity of Alocasia species seems to be centered in Southeast Asia.
The above-ground stem of elephant ear is different from the stem of taro (Colocasia esculenta), which is usually underground (unless the plant has been growing wild without replanting for a long time).
Xanthosoma sagittifolium ('yautia')
| |
 | |
Yautia growing in an experimental research field in Hanoi (photo courtesy R. Clarke, 2006) |
This aroid is a close relative of taro but is native to central America. The leaves are more pointed and the leaf stem attaches to the edge of the blade, close to the sinus (see photo, upright leaf at left). Yautia (as it is locally called in the Americas) was domesticated independently over an unknown period of time, but is certainly one of the ancient American crops.
Like many other South American crops (potato, sweetpotato, cassava, and corn for example) yautia has moved around the world in recent centuries. It is not yet common in New Zealand.
In tropical Asia, Africa and the Pacific yautia is commonly grown for food. In some places (e.g. Egypt) it is only used as an ornamental plant. In New Zealand it might do better than taro in hotter and drier areas, if the soil is good, and some water is available during the summer. It is more drought tolerant than taro, but also requries water to really thrive. Its potential for weediness in New Zealand is low.
