Ariocarpus trigonus, a
typical plant in the October flowering period.
rising slightly above ground level, globose, rounded on top, 5-25cm
high, 4-30cm in diam.; tubercles divergent, erect, not crowded or
basally compressed, acute at the apices, flattened and smooth
adaxially, not fissured, incurved strongly, 3-8cm long, 1-2.5cm
broad, usually twice as long as wide; spine-bearing portions of the
areoles absent at the tips of the tubercles; flowers 3-5cm in
diam., 2.5-4cm long; outer perianth parts pale yellow or
cream-colored occasionally with reddish mid-ribs, 1.5-3cm long,
3-4mm broad, mucronate but occasionally rounded
apically; inner perianth parts yellow or cream colored, 1.4-3cm long, 4- 8mm
broad; pistil occasionally exserted above the stamens;
style 1-2cm long; stigmas 6-10, 3-5.5mm long; fruit whitish or
greenish, 7-20mm long, 5-10mm in diam.