Betalains get their name from red beets (the genus Beta in the Chenopodiaceae), which are red in color due to the presence of the betalain. Certain betalains are responsible for the reddish flowers in another favorite holiday plant, the Christmas Cactus (Schlumbergera bridgesii). The discovery of betalains in cacti helped taxonomists understand the phylogenetic position of the Cactus family or Cactaceae. The Cactaceae were once classified in their own order near the carrot family (Apiaceae), but now the family is placed in a very different order, the Caryophyllales, along with the only other betalain-producing angiosperm families such as: Achatocarpaceae, Aizoaceae (with ice plants), Amaranthaceae, Basellaceae, Chenopodiaceae (with red beets and saltbushes), Didieriaceae, Nyctaginaceae (with Bougainvillea), Phytolaccaceae (with Pokeweed), and Portulacaceae.
Betalains are synthesised by a long chemical process from a common amino acid called tyrosine, the first step being the manufacture of L-Dopa (found in the animal brain - responsible for movement and mood) as above in alkaloids.
Betalains are a chemotaxonomically important group of water-soluble chromoalkaloids (red-violet betacyanins and yellow betaxanthins), which occur only in certain members of the plant order Caryophyllales (e. g. red beet) and some higher fungi (e. g. fly agaric).
The basic structure of betacyanins
Betalains are synthesized from the amino acid tyrosine through L-DOPA into the two subclasses, betacyanins (reds and purples) and betaxanthins (yellows).