Grusonia parishii

This is the first Grusonia flower in my greenhouse. Fully open flower is flat like a pancake, but soon after I has photographed it I noticed that the flower started to close, curling the petals back inside. This ephemeral shape seemed much more elegant to me, so I brought my camera back for it.

Matucana madisonorum

This is a more common Matucana, usually known as a naked ball with eventual spine or two. When grown on strong light, they actually develop long brown spines, somewhat twisted.

Mammillaria schiedeana 'plumosa'

The close-up of spines of Mammillaria schiedeana 'plumosa' shows that actually the spines are not 'feathery' like M. plumosa's. Each spine turns into fin hair-like stricture, giving the plant the overall 'puffy' look.

Rebutia fiebrisii

Many day-flowering cacti close buds for the night, protecting the precious pollen from the night moisture. Here is Rebutia at dusk, ready for the night.