Estudios en Cactaceae de Argentina: Maihueniopsis, Tephrocactus y géneros afines (Opuntioideae).

KIESLING, R.

Darwiniana

Instituto de Botánica Darwinion

Lugar: San isidro; Año: 1984 vol. 25 p. 171 - 215

0011-6793

In this work the author study the rehabilitation of the genus Maihueniopsis, analysing the generic differences among this genus, Puna, and Tephrocactus, the former two segregated from the later. Its also includes a chapter on the organography of Tephrocactus compared with segregated genera. The following are the principal characters on which the segregation is based: Tephrocactus species are lax shrubs, with crypt-shaped areoles, red glochids; spines of scaled epidermical cells orientated towards the apex (contrary to what is normal in Opuntioideae), dry and dehiscent fruits, seeds with auriculated soft aerenchymatic aril. These plants grows in Argentine low deserts.   Maihueniopsis species are compact cushions with more or less cylindrical normally developed areols, usually yellowish glochids, smooth spines, fleshy indehiscent fruits, soft to very hard non aerenchymatic arils, these without auricles. These plants grows in very high mountains and in the Patagonian plateau, from Ecuador and Chile to Argentina. In the case of the two species of Puna, the visible parts of these plants consist of only a few segments which grow at ground-level; their cylindrical areoles have no glochid except in the lowest ones in P. subterranean. In the only two species of these genus the epidermical cells of the spines are grouped into longitudinal lines and through, separated among themselves, they are lengthwise joined to the central body of the spine. Their flowers have reduced areoles. Fruits are dry, indehiscent; the seeds arils cover is soft, hairy-like. These plants grows in highlands between 2000 and 4000 m a.s.l. The taxonomical treatment included: key to the Opuntioideae genera which grow in Argentina and for the species of Tephrocactus and the Argentine ones of Maihueniopsis, descriptions, data of geographical distribution and ecology, illustration and exiccata. The following new combinations are given Mahihueniopsis darwinii var hickenii (Br. et Rose) Kiesling, M. minuta (Backbrg.) Kiesling, M. boliviana (S.-D.) Kiesling, M. nigrispina (K. Schumann) Kiesling, y M. pentlandii (S.-D.) Kiesling. Several neotypes are designated.