This is the flower of Napoleonaea vogelii. Bart Wursten describes the flowers of this intriguing species as “alien-looking”, resembling “something taken out of the ocean that was stuck on to the tree”. I really couldn’t have characterized it better myself.
Napoleonaea vogelii is a small evergreen cauliflorous tree that reaches heights spanning 4 to 20m (13-65 ft.). Like all members of its genus, it is native to the lowland humid rainforests of equatorial western Africa; Napoleonaea vogelii is the most widespread among this group of ten or so species. These trees follow a rhythmic growth pattern. This means that plants cycle between allocating resources to either elongation (growing taller or longer) or organogenesis (development and growth of leaves or fruit). While one is occurring, the other is paused. This can be contrasted with the the continuous growth patterns of most other plants, which are akin to multi-tasking; growth and development can simultaneously occur across all of the organs.
Composed of multiple whorls, the flowers are 3-4cm (~to 1.5 in.) wide and blossom exclusively from trunks and proximal branches, or cauliflory. Cauliflory is an adaption that describes woody plants with whom flowers and inflorescences grow directly from the trunk. The term cauliflory is derived from the Latin words caulis (stem) and floris (flower). However, caulis can also mean “cabbage”, which is how cauliflowers inherited almost the same English name from the same Latin origins (cabbage-flower). The authors of Napoleonaea vogelii (Lecythidaceae) Flowers in Relation to the Natural History of Insect Visitors speculate that these flowers may be among the most complex flowers of all extant flowering plants (they define complexity from the perspective of morphology rather than from an evolutionary lens). The linked paper is the source of most of my information about this species, as it is otherwise poorly-documented online.
The naming of the genus Napoleonaea in 1804 was inspired by Napoléon Bonaparte becoming the “Emperor of the French” in the same year.