Scientific Name:

Succulent perennial herbs or shrubs;  stems columnar, cylindric or flattened, often jointed and spiny.  Lvs usually 0 or very reduced and caducous.  Branches often furnished with areoles (± circular, cushion- like patches).  Fls solitary, ☿, usually actinomorphic. Calyx often petaloid and grading into petals.  Petals numerous, in several series, the innermost largest, sometimes coherent at base.  Stamens numerous, free or adnate to base of petals.  Ovary inferior, 1-locular, with 3 or more parietal placentas.  Ovules numerous;  style 1;  stigmas 2-many.  Fr. a berry, often spiny or bristly.  Seeds usually numerous, immersed in pulp.

[From:  Webb et al. (1988) Flora of New Zealand. Volume 4.]

Number of species in New Zealand within Cactaceae
Exotic: Fully Naturalised2
Exotic: Casual4
Cronquist, A. 1988: The evolution and classification of flowering plants. The New York Botanic Gardens, New York.
Mabberley, D.J. 2008: Mabberley's plant book, a portable dictionary of plants, their classification and uses. Edition 3. Cambridge University Press.