Xerophyte

Description

Echinocactus horizonthaloniusSN|1711]]SN|1711]] is a relatively small barrel cactus that normally grows unbranched.

Note

The Sonoran Desert populations of E. horizonthalonius have been segregated as var. nicholii, but are relatively similar to plants in New Mexico and the westernmost part of Texas.

Flowers

Pinkish-red , 5 to 7 (9) cm in diameter; stigma lobes pinkish to olive.

Blooming Season

From the end of March to late May (occasionally on September).

Spines

5 to 10 (more frequently 8) per areole, loosely projecting or strongly decurved, pink, grey, tan, or brown, strongly annulate-ridged, subulate, ± flattened, glabrous, generally not hiding stem surface.

Ribs

5 to 13 ribs (mostly 8), vertical to helically curving around stem, rib crests broadly rounded, uninterrupted or slightly constricted between areoles.

Stem

Pale, grey-green to bright glaucous grey-blue, flat-topped or hemispheric, and deep-seated in substrate, spherical with age or stoutly short cylindrical, stem slowly growing up to 30 cm tall, 15-20 cm in diameter or more. The apical meristem is protected by whitish-yellow wool, which shades developing flower buds and fruits.

Fruits

Red or pink, oblong, fleshy or semi dry and ephemeral, containing black seeds, indehiscent or weakly dehiscent through basal abscission pore. Once fruits are open, the rough black seeds (2 mm in diameter) lie on the wool atop plants, with seeds rolling off between the ribs.

Areoles

Round, full of white wool when young.