Short answers, pulled from the story.
Theaceae includes eight currently accepted genera: Apterosperma, Camellia, Franklinia, Gordonia, Polyspora, Pyrenaria, Schima, and Stewartia. The family contains flowering shrubs and trees, most famously the tea plant Camellia sinensis and ornamental camellias. Most species are native to China and East Asia.
Caffeine, theobromine, and theophylline are found only in Camellia section Thea, which includes C. sinensis, C. taliensis, and C. irrawadiensis. These compounds are absent from other species of Camellia and from all other Theaceae. The high caffeine content in the tea bush, which makes up 2.5-4% of leaf dry weight, is the result of artificial selection by humans.
Franklinia is endemic to the southeastern United States and is found nowhere else on earth. It is one of three Theaceae genera, alongside Gordonia and Stewartia, that have species native to that region.
Pseudopollen is a substance produced from connective cells in the stamens of Theaceae flowers, distinct from true pollen which comes from anthers. It has either rib-like or circular surface thickenings and is considered a distinctive characteristic of the family.
Eight genera are currently accepted within Theaceae. However, depending on the source and the method of classification used, the family has been described as having anywhere from seven to forty genera. The APG III system of 2009 placed Ternstroemiaceae in the separate family Pentaphylacaceae rather than within Theaceae.
The fossil Pentapetalum trifasciculandricus, dated to approximately ninety-one million years ago, may belong to either Theaceae or the closely related Pentaphylacaceae. Its classification remains uncertain, reflecting the deep shared ancestry of the two families.