The calyx consists of eight to ten, free, concave, and spirally arranged sepals which gradually increase in size from outer to inner, overlap in the bud, and do not fall after flowering.

These sepals are approximately oval in shape, leathery in consistency and are covered in simple one-celled straight or slightly curved hairs of 0.2-0.6 mm.

The five (or sometimes six) free petals are oval, much larger than the sepals, also overlap in the bud, but fall off after flowering, with a range in form that includes inverted egg-shaped.

The petals are thick, cream to yellow in color, sometimes with a purple blush, and with an irregular pattern of brown or red veins.

André Guillaumin realized both species were the same and should not be assigned to Montrouziera, so following the principle of priority according to the International Code of Nomenclature for algae, fungi, and plants he made the correct combination S. robusta in 1942.

Dickison, who made a thorough redescription of the species, agrees with most earlier authors that Strasburgeria would probably be an early branch of the Theales, with many characters in common with the Ochnaceae, but also noted important differences such as a much more primitive anatomy of the wood and much further developed morphology of the pollen.

[4] Recent genetic analysis revealed that Ixerba, an endemic of New Zealand, is closely related to Strasburgeria and it was assigned to the Strasburgeriaceae by the APG III in 2009.

The fact that it was found in western and southern Australia and in New Zealand suggests that the most recent common ancestor of Strasburgeria and Ixerba had developed by the time of the break-up of East-Gondwana.