Kalanchoe sexangularis open flowers

The open Kalanchoe sexangularis flowers in the photo each has four yellow petals forming the longish, erect corolla tube. The petals end in four spreading lobes in opposing pairs, bulging and more angular than rounded. There is a tiny channel visible towards the tips of some lobes in picture, as well as tiny protruding tip mucros. Yellow anther tips are present in the flower mouths, not exserted.

Flowering is staggered in the inflorescence, there being closed buds, even small ones, among open and withered flowers in the thyrse of several dichasia, the formal description of the arrangement of these flowers (Smith, et al, 2017; Leistner, (Ed.), 2000; iNaturalist).