Autor: Britton & Rose

Genus honouring Francis Lynde Stetson (1846-1920), of New York, who was a lawyer fascinated by botany. He was also an administrator of the New York Botanical Garden.
A monotypic genus of massive treelike plants reaching up to 8 m high, strongly branched (up to 100 or more), with a thick, well defined trunk, 40 cm in diameter and with branches erect or arching. Stems bluish green, club-shaped, not segmented, ribs 8-9, thick, more or less crenate. Areoles woolly; about 7-9 radial spines 3 cm long; 1 central spine which can reach 7 cm or more, straight and sharp.
Flowers nocturnal, self-sterile, but remaining open until the next day, funnel-shaped and widely spread, with pericarpel and long floral tube scaly, white, fragrant, pollinated by Sphingideae. Fruits globose to egg-shaped, fragrant, green tinged with red, edible, covered with scales, the remains of the dried perianth deciduous. Seeds rather small, roughly egg-shaped to cochleariform (spoon-shaped), brown to black, shiny, rough and warty. Seed dispersal assured by among others and in some specific regions – the tapir (Tapirus terrestris).
The monotypic genus Stetsonia grows in large but scattered colonies, at low or medium altitude, generally from 100- 900 m and more, rarely up to 2200 m in altitude, in dry areas, on hills, mountain slopes or shrubby pampas in Bolivia, in the deciduous dry forests of Paraguay, or arid plains of north-western Argentina, in Chaco, together with Cereus forbesii and Opuntia quimilo.
Argentina (Catamarca, Cordoba, Chaco, Corrientes, Formosa, Jujuy, Rioja, Salta, Santiago del Estero, Santa Fe), Bolivia (Santa Cruz, Tarija), Brazil (Rio Grande do Sul), Paraguay (Alto Paraguay, Boqueron, Concepcion, Presidente Hayes).

Currently only one recognised species:
– Stetsonia coryne* (Salm-Dyck) Britton & Rose 1920

References: "TAXONOMY of the CACTACEAE" -  ISBN 978-84-617-3692-8 (Vol. 2)