The variety in Opuntia's is enormous, both in size (from fragilis to echios, and from Puna to Autroclycindropuntia subulata). Pads can be small (fragilis) to large (robusta). Plants can be green to gray or blue (basilaris). Spines can be short to long or absent. Glochids can be few or numerous. Both spines and glochids come in a variety of colours. Also the way Opuntia's grow varies, from the flat ground huggers (humifusa) till tree forming giants (engelmannii, robusta and again the Opuntia's from the Galapagos). Flowers colours is anything between white and very dark red or purple, and everything in between. Multicolours is standard in some species (cespitosa, macrorhiza). And with hybrids the possibilites for colours is greatly increased.