Xerophyte

Habit

It is a large solitary, ribbed barrel cactus, becoming cylindric in age and attaining exceptionally a height of 3 metres.

Central Spines

7-13 in two series, reddish with yellow tips, greyish or brown, banded, somewhat curved, twisted and tangled, annulate, the main 4 forming a cross, upper and lower flattened, lateral two subulate, lower longest, less than 7 cm long, 6-10 mm wide, rather convolute and curved or booked at tip

Flowers

Funnelform, about 4 long and 3,5 cm in diameter, reddish with darker red midveins. Ovary with widely placed scales intergrading into obtuse, red, outer perianth segments. Inner inner perianth segments linear-lanceolate, 25 mm long, 5-7 mm. wide, midstripe lavender-red, margins yellow, serrulate. Filaments numerous, fine, appressed against style. Style 22 mm. long, yellow and red above, stigma lobes 9.

Blooming Season

The plants usually bloom during late spring or early summer, occasionally in late summer. Solitary bees are probably the most important pollinators. Ants visit extrafloral nectaries on the plant apex and may protect the cactus from insect herbivores.

Spines

Clearly differentiated into stout coloured centrals and fine, white radials.

Ribs

16 to 24, prominent, acute, slightly tuberculate and expanded under areoles, 2 cm. high.

Stem

Unbranched, deep green, at first globular and later cylindrical, erect, up to 1,5(or more) meters high (but usually about 70 cm), up to 30 wide.

Radial Spines

8-12 whitish, spreading, to 6 cm long, variable, slender, straight, flattened-setaceous,sometimes twisted, lower three stouter acicular to subulate.

Fruits

Oblong cylindrical, yellowish, 2,5 cm long, bearing broad rounded scales, not dehiscing by basal pores.Seeds. Rounded, somewhat angled, irregular, and slightly larger than those of gracilis, black and shiny.

Areoles

Young areoles light-grey felted, oval to elliptic, 15-20 mm long, 6 mm wide constricted between the flower and the spine-bearing section, 4 cm apart or even less in old plants.