a change, succession or difference, in the appearance or nature of things; in opposition to uniformity.

Botany, is a change in some less essential part or quality; as colour, size, pubescence or age.

Externally; by the plaiting or interweaving of the branches—by bundling or uniting of several stalks into one broad flat one; by the greater breadth or narrowness, or curling of leaves—by becoming awnless, or smooth, or hirsute. Internally; by becoming mutilated in the corolla; or having one larger than ordinary—by luxuriancy, multiplication, or fulness—by becoming proliferous, or crested—by bearing bulbs instead of seeds—or being viviparous.

The usual causes of variation are, climate, soil, exposure, heat, cold, winds, culture.