islayensis is a small
cylindrical cactus with very woolly areoles end dark spreading
spines, it is indeed very
variable and has received many names, but it is clear from fieldworks
that the different wild populations constitute a single but multiform
Stems: Grey-green, 5 to 40 cm
tall (or more long), 5 to 20 cm in diameter.
Ribs: 19 to 25 low and obtuse.
Areoles: Approximate, very
woolly, with grey-brown felt
Spines: Variable in colour, horn-coloured, brow to shiny black,
turning grey as they age.
Central spines: 4 to 7 spreading, thick, 12-16 mm long.
Radial spines: 12 to 22, shorter, radiating, (1-)6-10 mm long.
Flowers: Diurnal, 1,5 - 4 cm long and in diameter, born on
younger areoles from a yellowish
woolly crown in summer, wide
funnelform, yellow, outer perianth segments often reddish, floral tube
short with tufts of dense wool and long reddish bristles.
Fruits: Characteristic, up to 5 cm long, club shaped,
balloon-like, pinkish to red, openings at maturity by basal pores.
Pericarp initially fleshy but the interior always dry when mature.
Seeds: Broadly oval.
It is a
summer grower species that, like many
cacti of the Peruvian deserts, present some problems in cultivation.
It is in fact somewhat
rot prone if kept in a non
ventilated place. Require a very fast draining drying soil,
water regularly in summer, but do not overwater.
full sun exposure (or
light shade) Good heat tolerance.
Hardy to at least -5°C ( but probably can tolerate - 10° C for brief
Mature plants imported from the native habitats usually
did not take roots.
Usually propagated from Seeds.
(seldom produces offsets) or by grafting
onto a strong grafting stock like Selenicereus sp. Such grafted
seedlings can be been successfully cultivated for years.