Small, Flora of the Southeastern United States 817, 1933

Herbarium; Herbarium; Herbarium; Herbarium; Herbarium; Herbarium; Herbarium; Herbarium; Drawing (Britton and Rose v1, 1919)

Original Description

What is Opuntia austrina?

Opuntia austrina is a small, bushy prickly-pear of peninsular Florida, recognizable by compact shrubs with comparatively small cladodes and bright yellow flowers. It is treated here as distinct from other Florida taxa based on overall size and expression.

Details

Shrubs: low, bushy to short-ascending, forming compact clumps rather than a single trunked crown. Cladodes: relatively small for the complex (commonly a few centimeters long), narrowly obovate to elliptic; many joints taper at the attachment (“necked”). Areoles: variably armed, often with a single prominent spine on the upper half and sometimes a smaller, secondary spine; new spines pale, weathering whitish. Glochids: present in the areoles. Flowers: bright yellow. Fruits: reddish at maturity, typically small (about a few centimeters long).

Cytology

Reported as diploid. For molecular reference, see GenBank locus NC_083932.

Range & Habitat

Peninsular Florida.

Similar or Sympatric Species

O. ammophila — Typically more clearly trunked and gray-green, with a taller, tree-like look; austrina is lower and bushier with smaller cladodes.
O. stricta — Coastal beach-dune shrub, usually prostrate-ascending and more robust in coastal settings; differs in habit and typical fruit form.
O. dillenii — Coastal and morphologically distinct; pad/areole expression and coastal setting separate it from austrina.
O. humifusa — Widespread and commonly prostrate; austrina is more compact and bushy with consistently smaller pads in this treatment.

Other Notes

Earlier authors reported occurrence in southern Florida including the Keys. The name has been proposed as conspecific with O. ammophila (and O. polycarpa), but it is treated here as a stand-alone species. Attractive in gardens for its bright yellow flowers; not cold-hardy.

For more information, see:

For more information, see: Majure L.C., Judd W.S., Soltis P.S., and Soltis, D.E. (2017) Taxonomic revision of the Opuntia humifusa complex (Opuntieae: Cactaceae) of the eastern United States, Phytotaxa 290.