Colocasia esculenta (L.) Schott

Global description
 
Colocasia esculenta is an herbaceous plant without aerial stem, coming out of a large underground tuberous rhizome or from very fine tuberous runners. The leaves have a thick and fleshy petiole longer than the leaf blade, reaching 85 cm in length and sheathing at the base. The leaf blade is large, measuring up to 80 cm long and 50 cm wide, triangular or in arrowhead, completely glabrous to perfectly hydrophobic surface. The inflorescence is formed of a membranous envelope, erect, rolled and laterally open.23 to 30 cm long, yellow to orange yellow in colour. It enclosed within it a vertical column, 14 cm long, with female flowers reduced to obovate ovary in the lower region, a sterile area without flowers in the median part and the male flowers reduced to 3 or 5 welded stamens in its upper part and finally a conical terminal part, rough sterile
 
First leaves
 
The first leaves, coming out of the rhizomes, are carried by a long fleshy petiole, sheathing in the basal part. The lamina is generally triangular to sagittate, cordate at base, longer than wide, shortly acuminate at the top.
 
General habit
 
Perennial plant, without aerial stem, stoloniferous, with large tuberous rhizome with only the leaves being aerial, reaching 85 cm high.
 
Underground system
 
The underground system is formed of a large tuberous rhizome and of runners much thinner, with long internodes, allowing vegetative propagation from the rootstock. Numerous white fibrous roots come out of the rhizome.
 
Stem
 
Aerial stem is absent.
 
Leaf
 
The leaves are simple and grow in clumps from the underground rhizome. The petiole is longer than the leaf blade, reaching 85 cm in length. It is fleshy, thick, cylindrical, glabrous, green or tinted purple or dark purple in colour. The lower third is sheathing. It produces a transparent latex. The leaf blade is sagittate, reaching up to 80 cm long and 50 cm wide, obtuse to subacute and shortly acuminate at the top, cordate, sagittate at the base, peltate below the insertion point of the petiole. Basal lobes are fused at 1/3 to 2/3 of their length, the sinus is more or less triangular. The leaf blade is green or purple stained, with an entire margin. The midrib is palmate, trinervate at the base. The terminal lobe has 3 to 6 pairs of primary lateral veins which are quite straight, dividing into collecting veins at 1 to 2 mm from the margin, midrib of each basal lobe straight and emitting 3 to 4 lateral veins subparallel at the top side and a lateral rib at the base of the blade.
 
Inflorescence
 
The inflorescence is held by a vertically erect stalk,  reaching 50 cm in length. It consists of a long erect spathe, membranous, comprising of a rolled basal portion, 4 to 5 cm long, persistent and a terminal blade, pale yellow to orange yellow, 19 to 25 cm long by about 2, 5 cm wide, oblong and deciduous. Inside the spathe is a long spadix 11 to 14 cm long.
 
Flower
 
At the base of the spadix, at a height of 3.5 to 4.5 cm, are found the female flowers, reduced to obovate ovary, unilocular 2.8 mm long, mixed with white cylindrical staminode. The middle part of the spadix is sterile at a height of 1 cm. On the upper part, at a height of 4 to 4.5 cm, are the male flowers, reduced to 3 to 5 fused stamens. Finally the end part of the spadix, 1 to 3 cm long, is conical, sterile and rough.
 
Fruit
 
The fruit is a small berry with many seeds, whose development in nature is very rare.
 

Origin

Colocasia esculenta is present in the wild in tropical Asia, from where it extends to New Guinea and perhaps to northern Australia. A variety with long stolons is present throughout the region, and was proposed as the ancestor of cultivated taro on the basis of an analysis of ribosomal DNA. It is thought that taro was domesticated in northern India, but independent domestication in New Guinea has also been proposed.

Worldwide distribution

Species introduced in the south of the USA, Central America and all the tropical part of South America, Caribbean, Spain, Portugal, Italy, North and Central Africa, Indian Ocean islands, Australia and Pacific islands.

https://www.gbif.org/species/5330776