Xerophyte

Leaves

4 mm long, reddish, scale-like, conical, acute, produced beneath the areoles, on young segments only, soon shedding as segments mature.

Description

Opuntia robustaSN|32724]]SN|32724]], popularly known as the 'wheel cactus' in reference the circular shape of the segments, is a much branched, often erect, succulent shrub or small tree, sometimes 4-6 meters high, but commonly 1 to 2 m, with more or less distinct trunks. The branch segments (also known as joints, pads, articles or cladodes), are commonly thought of as leaves but are really flattened stems and are.armed with tufts of numerous barbed bristles (glochids) and commonly spineless of with 1 to 5 sharp spines to 4 cm long arising from each areole. Both plants with male flowers, plants with female blossoms and plants with hermaphrodite flowers can be found in Opuntia robustaSN|32724]]SN|32724]]. The fruits, which may be red, orange, yellow or green, are produced in profusion, possess thick peel (with sharp glochids) and juicy pulp containing numerous seeds; they are edible but best for animal feeding.

Note

the epithet 'robusta' is from the Latin for 'solid', 'strong' or 'robust' and apparently refers to the general appearance of the plant.

Flowers

5-7 cm long, to 5-8 cm broad at anthesis, bright yellow. Outer perianth segments rhomboid, or mucronate, reddish yellow with green tint in the center and apex. Inner perianth segments obovate, emarginate to mucronate, bright yellow. Pericarpel with few thick tubercles and tuft of glochids up to 3 mm long. Stigma-lobes green.

Spines

2 to 12, stout, subulate, flattened at the base, diverging, very diverse, brown or yellowish at base, white above, up to 5 cm long, but often wanting .

Stem

Trunk well-defined, branches to 1.5 (or more) m long from the base. Segments fleshy, flat, glabrous, orbicular to oblong, 15-40 (or even more) cm long by 10 to 28 cm broad, very thick, up to 2.5 cm thick, each weighing up to 2 kg, bluish green, glaucous, without red purple spots under the areoles.

Fruits

Globular to ellipsoid, at first more or less tuberculate, 7 to 9 cm long, deep red, but also orange, yellow or green, with light brown felt and yellow glochids c. 3 mm long. Pulp red.

Areoles

Somewhat elevated to slightly sunken, ovate, in 7 to 8 series, variable in size, 4-5.5 cm apart. With short black felt in the margin and yellowish white or brown felt in the centre. The glochids are numerous, yellowish to brownish, silky, thin, 1 to 18 mm long, glochids in the edges areoles of the pad are longer and more abundant up to 25 mm long.