Bac ha is the Vietnamese name for an Asian vegetable which is known by a variety of names in English including taro stem and elephant ear. The scientific name for the plant is Alocasia odora. The plant is native to Southeast Asia, and is available at Asian markets and specialty stores. It is also possible to grow bac ha at home, since it is often used as an ornamental plant in temperate and tropical gardens.
The plant is in the same family as taro, which leads some consumers to confuse the two. The use of “taro stems” to describe bac ha increases the confusion. However, the edible part of this plant is the stems, not the corms (something akin to bulbs), as is the case with taro. Although the corms can be eaten, the primary reason for cultivating the plant is the fleshy long stalks, not the corms. Just like with taro, however, bac ha must be carefully cooked before consumption, or the plant can stimulate an adverse reaction.
The reaction is caused by raphides, crystals of calcium oxalate which form in the cells of the stalks and corms of the plant. The crystals take on a needle-like structure, which causes them to pierce mucus membranes, resulting in irritation to the consumer. In taro, it is believed that other compounds may act in concert with these crystals to cause a reaction which can sometimes be extreme.
The stems of bac ha are crisp and slightly spongy, absorbing flavor very well in dishes like soups, stir fries, and meat platters. As they cook, they become tender and soft. This plant also has large heart shaped leaves, which are often removed before the plant is sent to market. At the market, bac ha stalks should be crisp, without any sign of wilting, sliminess, or extreme discoloration. They can be stored under refrigeration for up to one week.
In gardening, bac ha is sometimes referred to as upright elephant ears, since the broad leaves stand straight up from the stalks, rather than drooping. As the plant produces new stalks, it slowly grows taller, and can top six feet (two meters) in height in good growing conditions. The plant prefers tropical to substropical conditions, and does not do well in cold weather. If the plant is not happy with its growing conditions, it will go dormant, producing smaller and smaller leaves until it dies off altogether. However, if the root is still sound, the bac ha can be revived.