The Rocky ridge is a steep wall made of travertine and red tuff, delimiting the southern flat area of the Desert. The site shows microclimatic and pedological characteristics that differ from the surrounding areas due to factors such as its south-facing position, its shelter from cold winds, and its poor water stagnation. This is the hottest area of the Botanical Garden, housing species of small size such as small globular cactus, located in natural cavities or manually dug into the rock. Over the years these species, perfectly acclimatized, have made precious the already impressive rocky wall. Many of these species not only survive the harsh winter, but they grow very rapidly, resulting in “tree-like” and “monumental” habitus
The first specimens were planted between 1995 and 1996, then in 2002 the collection was enriched with the introduction of over a hundred plants, with excellent results in taking root. Finally, the collection was further expanded between 2012 and 2014. Hundreds of specimens belong to the family Cactaceae, including the genera Mammillaria Haw., Stenocactus (K. Schum.) A. Berger, Echinocactus Link & Otto, Ferocactus Britton & Rose, Turbinicarpus (Backeb.) Buxb. & Backeb., Astrophytum Lem., Hamatocactus Britton & Rose, Echinocereus Engelm., and rare species such as Turbinicarpus valdezianus (M.Moller) Glass & R.A.Foster and Pelecyphora aselliformis Ehrenb. Among the species common on rock, Agave victoriae-reginae T. Moore and Dasylirion serratifolium (Kaw. ex Schult. f.) Zucc are very well acclimatized; the latter, firstly present with few specimens, reproduces naturally and is now present with many specimens.
The plants come from private collections, seeds collected in nature (Mexico) and partly propagated at the Botanical Garden. They are not irrigated or fertilized, they do not undergo transplants or pesticide treatments, and they are not protected during the winter; the only cure they receive is the manual elimination of unwanted spontaneous herbaceous plants. This practice, necessary to guarantee the area an “arid aspect”, is imperative for their survival, or they could not compete with fast-growing herbs or shrubs.
These plants proved to be free from parasites (mealybugs and mites) that instead characterize specimens growing in a protected environment (greenhouse), therefore allowing them to not be treated with pesticide.
The Botanical Garden houses a rich collection of succulent plants (“succulents”) organized into several distinct sections based on the type of management and location; in addition to the rocky ridge, other succulents are housed in the Greenhouse of Patriarchs, in the Greenhouse Astolfi and in the Desert.
