Griffiths, Annual Report of the Missouri Botanical Garden 22: 25, 1911

Holotype; Isotype; Isotype; Isotype; Isotype; Isotype; Herbarium; Drawing (seed)

O. bentonii is different from O. anahuacensis, but they are both beach prickly pears.
O. bentonii is different from O. stricta, but they are both beach prickly pears.

Original Description

What is Opuntia bentonii?

A beach-dune prickly pear of the upper Texas Gulf Coast (with reports from adjacent southwestern Louisiana), distinct from superficially similar coastal taxa.

Details

Shrubs: open, erect plants generally <50 cm tall, occasionally to ~80 cm. Cladodes: chiefly obovate, also oval/elliptical/subcircular; ~16 cm wide × ~27 cm long; relatively thin; veins often visible between areoles so areoles can appear slightly raised. Areoles: upper areoles with 1–3 (to 5) spines; spines yellow, somewhat translucent, erect to sometimes recurved, often short and in some plants confined to pad margins. Glochids: present; concentrated apically or more diffuse. Flowers: large (to ~9–10 cm across); style greenish-white; stigma lobes yellowish-green to yellow (not green). Fruits: egg-shaped to short-pyriform; umbilicus raised early, flattening with maturity. Leaves: small, recurved, to ~5 mm long. Seeds: comparatively large—about 40% greater diameter than those of O. lindheimeri (useful diagnostically).

Cytology

Ploidy unknown.

Similar or Sympatric Species

• O. lindheimeri — larger plants overall; stigmas distinctly green (contrast with yellow to yellow-green here).
  https://www.opuntiads.com/opuntia-lindheimeri/

• O. anahuacensis — coastal and thicket-forming, often prostrate/reclining with possible pad “necks”; O. bentonii more erect and shrubby.
  https://www.opuntiads.com/opuntia-anahuacensis/

• O. stricta — another beach-dune species; differs in habit and other characters.
  https://www.opuntiads.com/opuntia-stricta/

Other Notes

Observed on the upper Texas Gulf Coast (e.g., Bolivar Peninsula, Sea Rim State Park near Port Arthur) with reports from southwestern Louisiana; not documented inland. Plants stay low and open in cultivation. Bright yellow flowers with yellow to yellow-green stigmas help separate O. bentonii from O. lindheimeri (green stigmas). Seed size is notably larger than in O. lindheimeri. Slightly raised inter-areolar veins may persist for one to two years on pads.

For more information, see:

Shaw, J. & Ferguson, D. J. (2025). Opuntia bentonii: A Texas Gulf Coast beach cactus (Cactaceae: Opuntioideae). J. Bot. Res. Inst. Texas, 19:17–26.
https://www.opuntiads.com/records/opuntia-bentonii-published-JBRIT.pdf