Sechium edule

A monoecious, vigorous, perennial herbaceous vine with a large tuberous root. Stem climbing or sprawling, longitudinally grooved, growing 10-15 m in a single season. Tendrils large, 2- to 5-branched. Leaves simple, spirally arranged, petiole 3-25 cm long, leaf-blade broadly ovate-circular in outline, 7-25 cm in diameter, base deeply cordate, 3- to 7-angular or lobed, acute, margins obtusely dentate, scabrid hairy. Inflorescences axillary racemes with small, greenish or cream, 5-merous flowers, hypanthium saucer-shaped, with 10 pouch-like nectaries on the bottom, male racemes with peduncle 6-30 cm long, 10- to 30-flowered, stamens 5, filaments united, female flowers usually solitary on short pedicels, in same axil as male, corolla ca. 2 mm in diameter, connate style and stigmas, forming a small head. Fruit a one-seeded fleshy berry, variable, commonly pear-shaped, 7-20 cm long, somewhat ribbed, smooth or shortly spiny, dark green to almost white, fruit stalk 2-3 cm long, pendent, pulp white or greenish-white. Seed solitary, ovoid to ellipsoid, 2.5-5 cm long, compressed, white, germinating within the fruit, usually while the fruit is still attached to the plant, in some genotypes seed-coat with fibres radiating into the flesh, in others obsolescent and the flesh fibreless.;Other botanical information: The genus Sechium P. Browne has long been considered as monotypic with S. edule as the only species. Since the 1970s wider genus concepts have been proposed, including 3-9 species, all indigenous to Central America. S. compositum (Donn. Smith) C. Jeffrey, occurring in southern Mexico and in Guatemala, is considered the closest wild relative of S. edule. Its fruit is bitter and it bears spines along its 5-10 ridges. Chayote cultivars do not breed true, although it has been observed that cultivars do not segregate significantly from one generation to the next because of the relative isolation of chayote plants from one another when planted in home gardens. When planted together, complete panmixy can be observed. Substantial efforts made at CATIE (Costa Rica) to describe cultivars on the basis of fruit characteristics proved to be of limited relevance because of the extraordinary variability, with continuous variation in almost all the characters. The variable fruit characters include size (7-20 cm long), weight (100-1000 g), colour (continuous range from white to dark green), shape, fruit-wall features (spines, lenticels, grooves and ridges), flavour and texture. Nevertheless, farmers 'classify' the genotypes by a combination of such fruit characteristics. Instead of speaking of cultivars, it seems best to consider those types as landraces or as primitive populations. At least 25 landraces exist in Central America. Commercially grown chayote consists of two types: a medium sized, light-green, smooth, pear-shaped fruit and a small, white, smooth, globular one. Several types can be distinguished in South-East Asia. For example, in West Java (Indonesia) the common type is dark green and almost glabrous, but more spiny and lighter green types can be found. A complete white type, less tender and spiny, is sometimes grown as a botanical curiosity.