Orostachys


Orostachys is a genus of the succulent family Crassulaceae that contains about 15 species. It is a biennial herb growing in China, Japan, Kazakhstan, Korea, Mongolia, Russia. Eight species occur in China.

Description

Orostachys are the most morphologically distinct member of subfamily Sempervivoideae, characterised by a semi-rosette habit, and spadix-like terminal, narrowly pyramidal to cylindrical inflorescence. leaves are linear to ovate, often with dull purple dots. The stem arrangement is alternate, forming a crowded cauline rosette. The roots are fibrous and it has no rhizome. The flowering stem is solitary, arising from the center of the rosette in the second year.

Taxonomy

Within family Crassulaceae, Orostachys is placed in tribe Telephieae of subfamily Sempervivoideae. The genus has. at times, included Meterostachys. Molecular phylogenetics shows that the genus is not monophyletic, but polyphyletic relative to paraphyletic Hylotelephium. Its circumscription, therefore, is unstable and subject to revision.

Subdivision

The genus Orostachys has been divided into series, including:
Other authors have created two different sections:
Some species were transferred from Sinocrassula into Orostachys, as section Schoenlandia, also treated as a subgenus or section,,, or a separate genus Kungia, e.g. O. schoenlandii. Orostachys section Orostachys, in turn has been treated as two subsections, differing by either flat or fleshy leaf shape, and the presence or absence of appendages on the leaves, which include spines or cartilaginous protrusions:
On the basis of molecular data, it has been proposed that Orostachys subsection Appendiculatae be considered a separate genus.

Species

The genus includes about 12–17 accepted species, including: