Orostachys spinosa

by Kristl Walek

Orostachys is a member of the Crassulaceae family, which includes other well-known succulents such as Sedum, Sempervivum and Rhodiola. It is a small genus of plants classified into thirteen species native to Russia, Mongolia, Korea, Japan, Kazakhstan and China. Most are rubbery-foliaged plants with an outward growth habit. Some have been, or still are classified as Sedums.

Orostachys spinosa is native to Siberia, Mongolia and across Asia growing on dry, rocky slopes in the wild. In recent studies of plants growing on the Russian desert-steppe, it was determined "to be amongst the most cold-adapted plants known." It is hardy to at least –40°C.

In a genus of largely fleshy, spreading plants, O. spinosa is the odd man out. It is often mistaken for a Sempervivum, although it is decidedly more elegant; forming a low, spiny, grey, globose rosette which can be 10cm across at maturity. This normally takes a minimum of 5 years and at its peak, the plant is a wonder to behold and a perfect study in symmetry. The rosettes are evergreen and emerge from winter shrunken and tight, shimmering like grey-green metal. The rosette expands and opens as the season progresses and changes to soft grey-green.

Like Sempervivum, O. spinosa is monocarpic, and the individual rosette dies once it flowers. However, new rosettes form in a circle at the base of the mature plant, which are normally removed and grown individually. It is always sad when the flowering year arrives, coinciding as it does with the plant's peak of perfection and size. One knows when the time has come; the centre of the rosette bulges upward and rises, turning into a wide-based raceme of insignificant small yellowish flowers. The phallic flower spike is described in more polite circles as having the shape of "an inverted ice-cream cone." Succulents are too rarely included in the rock garden, notwithstanding the fascinating textual addition they can provide. Orostachys spinosa in particular would look at home growing with most alpines or planted in a trough.

Orostachys is fast from seed; moisture and a bit of warmth quickly produce an ocean of plants. The seedlings are a bit of a challenge to raise as they remain tiny for a long period and, like many cacti infants, need more moisture than expected.