A wild variety of a plant may show different variations. Humans have selected some such variants and grown them for generations and during the course of time, they have become totally different species.
For example, variants in wild cabbage were selected on the basis of certain features to generate different vegetables.
(i) Short distances between leaves, led to formation of green leaf buds-the common cabbage.
(ii) Arrested flower development has bred broccoli.
(iii) The variant with sterile flowers has made the cauliflower.
(iv) Variant with swollen leaf parts-kohlrabi.
(v) Variant with larger leaves-kale.