Alocasia macrorrhizos or Elephant Ear is a spectacular plant with huge leaves.
Its vigorous growth requires frequent fertilizing.
This giant can be grown in the garden as well as indoors as in a pond.
In colder climates it is best grown in pots and overwintered indoors, although it can withstand light frost.
Alocasia macrorrhizos ‘Violacea’ or Black Giant Taro is a huge arum-like with thickened underground rhizome or tuber. In tropical conditions it forms a trunk of 10 cm in diameter and about 2 m high. In culture, it is rarely higher than 2 m high.
The leaves grow from the tuber, at the center of the plant. Each new leaf is larger than the previous one. The leaf can be up to 1 m long and 60 cm wide, on a petiole of up to 130 cm long. The leaves are dark green to dark purple, erect and arrow-shaped. Petioles are dark purple, nearly black.
The inflorescence consists of a white spadix surrounded by a pale green bract of 15-35 cm long. They curl back with time. The male flowers are located at the top of the spadix, the female flowers at the bottom. At the end of the spadix is a yellowish appendix, at least half as large as the entire length of the spadix, and covered with small irregular grooves.
The fruits are red berries of 1 cm in diameter, each containing a few light brown seeds of 4 mm in diameter.
Black elephant ear, black giant Alocasia, black giant taro
Alocasia alba, Alocasia crassifolia, Alocasia indica, Alocasia macrorrhiza, Arum indicum, Colocasia indica
Alocasia: from the Greek a- (without) and locasia (lotus root)
Macrorrhizos: from the Greek makros (big) and rhizoma (root)
South-east Asia, but now widespread throughout the tropics
USDA zones 9-11: above ground parts die back at 0 °C, tuber resistant to -4 °C for short periods
Fertile and moist
Plenty of water, substrate may be wet. Can be grown in a pond provided the water contains sufficient nitrogen (fish in the will provide that) and oxygen (preferably oxygenator or a fountain or waterfall)
Regular fertilizing during the growing period: weekly with liquid universal fertilizer
At the planting site, width is more important than the depth.
Tubers can be planted in the garden for the summer, then dug up in the winter and kept sheltered from frost.The plant can also be grown outdoors in pots in the summer, indoors in the winter
The plant is poisonous in all parts. Touching the sap with bare skin sap may cause irritation.
By division in spring