Xerophyte

Description

Pterocactus araucanusSN|30778]]SN|30778]] is a geophyte cactus with a massive underground tap-root, and several deciduous stems with spines not covering them. This plant grows in sandy soil, with almost the entire plant underground. P. araucanus is one of the best-loved species in cultivation because it is not supposed to have glochids.

Roots

This species forms thick rootstocks constricted at the collar that help to survive the dry periods.

Glochids

Usually absent, but in some forms a few glochids may appear after the juvenile stage.

Blooming Season

Summer.

Crested Growth

The crested (Pterocactus araucanusSN|30778]]SN|30778]] f. cristata) is a very rare, slow-growing and highly priced crested cactus forming odd sculptural shapes. In crested plants the growth point of the stem has switched from a geometric point, to a line, which folds and undulates as the crest expands. Though these crested Pterocacti are somewhat rare, cresting occurs naturally throughout the range of the of the species,and can be encountered in cultivation too.

Spines

About 8, pectinate, yellowish with darker tips, to 3 mm long. Sometime a long and powerful central spine is produced in the centre of developed segments.Flowers Diurnal reddish brown, opaque, 3-4 cm in diameter. The flowers are terminal produced from the apex of new growth. Stamens and style are yellow.

Stem

Its stems fan out, some will form stable crests while others (the more common) make both crested and normal stems. Epidermis grey-brown. The whole plant up to 10 (or more) cm wide.

Fruits

Borne apically, dry at maturity, globose, 2 cm in diameter, transversely dehiscent at apex.

Areoles

Elliptical, 2 mm long and 1 mm wide.