Sedum - Stonecrops Linnaeus (1757)

Sedum is a large genus of over 400 species distributed through the Northern hemisphere. Most species are succulent, varying from mat-forming stonecrops to small shrubs.

In Great Britain, S. acre and S. album may be found growing in short grassland and among rocks. S. acre ( Biting Stonecrop ) contains piperidine alkaloids, making it toxic or at least irritating to herbivores. On the other hand, S. reflexum (Stone Orpine) is considered edible as a salad ingredient. Another British native plant, formerly S. rosea ( Roseroot ) has been moved to the Genus Rhodiola.

Many Sedums are frost-hardy and suitable for a sunny garden. The water-retaining properties of Sedum leaves allows them to be used as drought resistant plants. Creeping stonecrops can be planted in cracks in paving and tolerate being walked on occasionally. Any bits that break off will likely find a crack to root in. S. spectabile and S. telephium provide useful flower colour in the garden in late summer and early autumn. Numerous cultivars are available.
In some countries, Sedums have been used as green roof coverings, a trend that seems likely to continue. Ready-grown mats of mixed Sedums are grown commercially for this purpose.


Sedum harvardii Chisos Mountains, Texas	Sedum rupestre c.v. angelina	Sedum telephium	Sedum wrightii Chisos Mountains, Texas

Sedum sp. San Bernardino Mountains, Ca.

Orostachys Fischer (1809)

Orostachys is a genus of 13 small rosetted succulents from Russia, Pakistan, Kazakhstan, Mongolia, China, Korea and Japan, variously included under Sedum and Cotyledon. Some species have more succulent leaves than others. Each leaf carries a terminal spine. Plants are monocarpic but may persist by propagating themselves via stolons. Hundreds of pink or white bell-shaped flowers are carried on dense pyrimidal spikes.

Orostachys spinosa is a cold-tolerant alpine from Siberia and Mongolia, with fleshy leaves arranged according to the Fibonacci sequence. The mature rosette may be 4 inches in diameter after several years. It must be kept dry during winter dormancy and otherwise watered sparingly, avoiding getting water on the rosette. Bright light or diffuse sunlight helps to keep the rosette compact.
As with other Crassulaceae Orostachys spinosa employs Crassulacean Acid Metabolism (CAM) and is thought to be the most cold-tolerant CAM plant known. The relatively high sugar content of the leaves, compared with starch, may help it to survive extreme freezing temperatures to -40°C and even carry out photosynthesis under snow cover in its habitat.

Orostachys spinosa