Aeoniums have been found in the Canary Islands and have been known about throughout europe as far back as at least 1711. Originally, the rosette succulence of the leafs lumped them together with sempervivums, but in 1836 they were elevated to their own class.
Aeoniums thrive outdoors in areas that similate a Mediterranean climate, wet winters and dry summers. In a cooler climate they become hardy container plants. There are many distinct vegetative features that can be used to differentiate aeoniums from other rosette succulents. First, all aeoniums lack a leaf stem. Their leaves gradually tapper towards the stem and clasp the stem. Aeonium leaves are also not as succulent as compared to the echeveria or its hybrid graptoveria. Many of the aeoniums also have sticky leaves caused by small leaf hairs which is believed to help in their water retentiveness. Aeoniums can also differ in a number of vegetative aspects. The size of a leaf can range between a 1/4" long to over 2' pending on the variety. The heights of the plant can range between small shrubs, or shrubs reaching over 6’ tall. Sometimes they appear as stalky singular plants, or fist sized clumps that look nothing like other aeoniums in its family.
Aeoniums have two different drought strategies used in surviving the drier summers. One group will shed all of its older leaves and retain only the newest growth, which are then curled into a tight ball during summer dormancy. The other group produces two distinct leaf shapes pending on season. The winter leaves are long and somewhat floppy, where the summer leaves, will appear short, tight, and have somewhat flattened rosette. Once rain commences again in the fall, the leaves will open up again and new, regular growth, will continue.
The flowering inflorescnes in aeoniums rises from the center of the rosette. The rosette that bares this flower will then die after its flowered, better known as being monocarpic. The roots of an aeonium are thin and fibrous. The root system is mostly shallow and grows close to the surface when planted in the ground. In habitat the growth cycle for an aeonium is winter growth/summer dormancy, but if grown in a cool coastal environment, many species will continue to produce new growth all year.
Aeoniums also don’t like multiple days of temperatures in excess of 100 degrees. They will often suffer from heat damage if those conditions arise. Frost tolerance can also vary between species, but most will show a frost burn at freezing temperatures, but they should recover quickly if no further frosts occur. These plants are also only considered only mildly drought tolerant because their habitat always has a wet season, so they never need to endure more than six months without rain. However, here in Orange County, and the rest of Southern California, they would be considered highly drought tolerant because their needs fit that of the climate. Because our climate is so ideal for these plants they thrive and show tremendous growth through the winter months.