Aeonium, evergreen succulent, slow growth, size and color vary, open heavily branched growth habit, fleshy dark purple to green rosettes on long stems, full sun to part shade, tolerates some drought, excellent container plant.
Among the best succulents for decorative effects, in pots or in the ground. Fleshy leaves are held in rosettes at branch tips. After several years, rosettes produce a single flower stalk in spring or summer; branches that have flowered die.
With age, plants become leggy; to encourage branching, cut back branches several inches below rosettes. Cuttings are easily rooted: let dry for a few days, then plant in sandy soil and keep barely moist until new growth appears.
Most Aeoniums come originally from the Canary Islands off the coast of Spain in the Atlantic Ocean, with a few oddball species from several isolated parts of central Africa. The climate of the Canary Islands is fairly Mediterranean so these plants are perfectly adapted to many similar climates around the globe. Most are moderately drought tolerant (though less so than most might guess), mildly frost tolerant (some more than others), but only moderately heat tolerant as well, and dependent on bright light to full sun. These are generalizations and there is certainly some variation in their water, heat and lighting needs.
Aeoniums are members of the Crassulaceae, a huge family of succulents that include many other popular and commonly grown succulents, including some that look a lot like Aeoniums. Echeverias in particular are often confused with Aeoniums and there are several other rosette-like succulents (eg. Dudleyas, Graptopetalums, Pachyverias and Graptoverias). One thing that sets t these plants apart is the way their leaves attach to the stem- they are wrapped around the stem with a fibrous attachment so that when a leaf is pulled away, the stem is intact with only a transverse line showing where the leaf was attached. The other rosette Crassulaceas have succulent attachments and their being pulled off the stem leaves a divot in the stem.
A lot more information on Aeoniums is available here: http://davesgarden.com/guides/articles/view/1058/#b