"Succulents A to Z" contains Debra's "favorite foolhardy succulents for gardens large and small." Organized in alphabetical order, this section describes the best species and cultivars from all common succulent genera-from aeoniums to yuccas. They are a member the Euphorbia group, which includes over 2000 species cacti and succulents. Some cacti species don't need to be watered at all during the cold months until a new growth cycle starts in spring. It's not bad considering it can withstand the heat of the desert and temperatures down to minus 20 degrees Celsius.