Opuntia aciculata — *Opuntia* *aciculata*

Griffiths, Proceedings of the Biological Society of Washington 29(3): 10, 1916

Lectotype; Isolectotype; Herbarium; Herbarium; Herbarium; Color Plate (Britton and Rose, v1 1919, plate XXVIII)

Original Citation

What is Opuntia acicualta?

Opuntia aciculata is a medium-to-robust prickly-pear distinguished by the chenille-like rings of long, bristly glochids at each areole. True spines are absent or few and short, often angled slightly downward. It has been confused with O. engelmannii, O. lindheimeri, and O. strigil, but the dense glochid wreaths and typically sparse spines—along with frequent yellow flowers—separate it well in the field.

O. aciculata is tetraploid.

Details

Shrubs: low, hemispherical clumps to about 1 m tall and up to ~2 m across; primary branches ascending or partly prostrate, with secondary branches upright. Cladodes: obovate to ovate, to roughly 15 × 20 cm; joints may blush pink in hard freezes. Areoles: small and usually spineless; where spines occur, expect 1(–2) short, slightly downward-pointing spines. Glochids: numerous and conspicuous in chenille-like rings (about 0.5–1(–2) cm), readily irritating on contact. Flowers: most often yellow, sometimes shading toward orange or red; about 9 cm across. Fruits: obovate to short-pyriform with a glaucous bloom, maturing light purplish-red.

Cytology

Published counts indicate polyploidy in this complex; O. alta is most often reported as tetraploid, though local cytotypes may vary.

Range and Habitat

In the United States it is known along the lower Rio Grande in south Texas (Webb County, Laredo area), likely as a waif or from cultivation. In northeastern Mexico it occurs in thornscrub on rocky or limestone substrates, including parts of Nuevo León and Tamaulipas. It is widely grown and can persist near old plantings.