Xerophyte

Central Spines

4 to 7 spreading, thick, 12-16 mm long.

Seeds

Broadly oval.

Roots

Fibrous.

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.

Spines

Variable in colour, horn-coloured, brow to shiny black, turning grey as they age.

Ribs

19 to 25 low and obtuse.

Stem

Grey-green, 5 to 40 cm tall (or more long), 5 to 20 cm in diameter.

Radial Spines

12 to 22, shorter, radiating, (1-)6-10 mm long.

Fruits

Islaya longicarpaSN|1716]]SN|16607]] distinguish for its comparatively very long fruits, up to 10 cm long, club shaped, pinkish, openings at maturity by basal pores. Pericarp initially fleshy but the interior always dry when mature.

Areoles

Approximate, large, very woolly, with grey-brown felt.