Xerophyte

Habit

Usually solitary or very slow to offset, develops a squat and highly ribbed stem with a flattened top.

Central Spines

Most often 1-2 (rarely more) slightly curved, sometimes scaly with age, usually very short or occasionally up to 6 cm long.

Description

Thelocactus rinconensisSN|10887]]SN|10887]] subs. phymatothelos, better known as Thelocactus phymatothelos, can be distinguished from other forms of the Thelocactus rinconensis complex because the stem is always strongly depressed and glaucous, the spines are few, shorter and slightly curved, and the flowers are more or less clear pink.

Flowers

3-5 cm long, 2,7-3 cm in diameter, white to pinkish with a pink midstripe. Tube short, pericarpels coveredwith scales. The plants usually fail to flower until they are 5-9 years old.

Spines

Usually short but variable in length, depending on the clone, dark, usually black-brown , pale at apex, but also grey, brown or yellow, with a distinctive silvery appearance, and sometimes shredding. Spines in old age shiny grey-white.

Ribs

Mostly obscured by tubercles that are very prominent angled but more rounded and compressed than those of the main species Thelocactus rinconensisSN|10887]]SN|10887]]. Tubercles up to 1,5 cm hight.

Stem

Spherical with a compressed top, 9-15(-20) cm across, ap to 10 cm tall, chalky-grey, silvery-grey, glaucous sometimes tinged with purple.

Radial Spines

up to 5 (usually only1-2) similar to the centrals, erect to radiating, slightly curved shorter than the centrals.

Fruits

Spherical ta oblong with scales, 7-9 mm in diameter, greenish or yellowish, slightly fleshy when ripe, opening by basal pore.

Areoles

Round to elongate, mostly more than 2 cm apart and without nectaries.