Cactaceae: The cactus plant family of the order Caryophyllales, subclass Caryophyllidae, class Magnoliopsida. Cacti are succulent perennial plants well adapted to dry regions.Opuntia: A plant genus of the family CACTACEAE. Species with cylindrical joints are called Cholla; flat jointed ones are Prickly-pear.Germination: The initial stages of the growth of SEEDS into a SEEDLINGS. The embryonic shoot (plumule) and embryonic PLANT ROOTS (radicle) emerge and grow upwards and downwards respectively. Food reserves for germination come from endosperm tissue within the seed and/or from the seed leaves (COTYLEDON). (Concise Dictionary of Biology, 1990)Seeds: The encapsulated embryos of flowering plants. They are used as is or for animal feed because of the high content of concentrated nutrients like starches, proteins, and fats. Rapeseed, cottonseed, and sunflower seed are also produced for the oils (fats) they yield.