OAXACANUM Rose, 1911

Synonym : Sedum polyrhizum  Praeger (1921) *

Distribution : Mexico (Oaxaca), ± 3500 m

Description (according to IHSP, 2003) :

Tufted perennial herbs with roughened prostrate much-branched stems, rooting, to 15 cm long.

Leaves alternate, oblong to obovate, obtuse, slightly mamillate, broadly spurred, subterete, 3 - 6 mm.

Inflorescence : flowering branches erect, inflorescence few-flowered leafy corymbs

Flowers 5-merous, sessile or subsessile, sepals broadly sessile, equal, linear to narrowly triangular, subobtuse, 3 - 4 mm, suberect, petals almost free to the base, sub-oblong, obtuse, broad below the tip, narrowly mucronate, yellow, 7 - 8 mm, suberect.

Cytology: 2n = 68.

* The incompletely known S. polyrhizum may belong here or may as well belong to S. australe.

Ray Stephenson (Sedum, Cultivated Stonecrops, 1994, p 259)

Sedum oaxacanum is a fairly common species in succulent collections, often bearing the label S. australe, which is a similar species (not in cultivation) with terete leaves. Alternate leaves, which cluster into rosettes on tips of 8-cm (3-in) long stems, are pruinose, especially when new. Purple, trailing stems are rough-papillose with tips erect. The overall effect is quite charming. Yellow flowers are produced sparsely in early summer.

Habitat : Central Oaxaca on Cerro de San Felipe at 3500 m (11,500 ft) is the main home of this stonecrop, but it is also reported from southern Puebla.

Main points of distinction : Scurfy-white flattish, papillose, spurred leaves are quite distinct. Yellow kyphocarpic flowers have equal sepals, and petals with stamens inserted 2 mm (0.08 in) from the base, n = 34. This stonecrop resembles, and is often seen masquerading as, one of several South African Crassula species, especially C. dasyphylla, a plant with tiny flowers and a single whorl of stamens.

Variation : Most plants in cultivation have been propagated vegetatively over a couple of generations, but a new distribution from a lower altitude in San Miguel Aztatla, Sierra Mixteca, appears identical.

Horticulture : This is a delightful species for a small earthenware container where it can creep over the edge. Seing from such a high altitude, it is half-hardy and worth trying outdoors in warmer areas.

Cultivated in a rockery, in Basque Country, France

Photo Emmanuelle Aubé