The five-lobed calyx of a Silene crassifolia subsp. crassifolia flower is from 10 mm to 13 mm long and hairy. The sepals are joined in a long tube without bracts at its base.

In the absence of open flowers, these green calyces are conspicuous, purple-ribbed longitudinally. Square at the base and bulging before the tip, there is a constriction near the base of old flowers that have lost their corollas; not so much on the thinner new flowers or buds.

The flowers grow at the tips of short branches in a kind of panicle of up to seven flowers (Bond and Goldblatt, 1984; iSpot).