Why do so many rich tropical spices come from a few basal branches of the plant evolutionary tree? Katherine looks to their ancestral roots and finds a cake recipe for the mesozoic diet.
I think it was the Basal Angiosperm Cake that established our friendship a decade ago. Jeanne was the only student in my plant taxonomy class to appreciate the phylogeny-based cake I had made to mark the birthday of my co-teacher and colleague, Will Cornwell. Although I am genuinely fond of Will, I confess to using his birthday as an excuse to play around with ingredients derived from the lowermost branches of the flowering plant evolutionary tree. The recipe wasn’t even pure, since I abandoned the phylogenetically apt avocado for a crowd-pleasing evolutionary new-comer, chocolate. It also included flour and sugar, both monocots. As flawed as it was, the cake episode showed that Jeanne and I share some unusual intellectual character states – synapomorphies of the brain – and it launched our botanical collaborations.
Branches at the base of the angiosperm tree
The basal angiosperms (broadly construed) are the groups that diverged from the rest of the flowering plants (angiosperms) relatively early in their evolution. They give us the highly aromatic spices that inspired my cake – star anise, black pepper, bay leaf, cinnamon, and nutmeg. They also include water lilies and some familiar tree species – magnolias, tulip tree (Liriodendron), bay laurels, avocado, pawpaw (Asimina), and sassafras.
It would be a mistake to call these basal groups “primitive,” since they have been evolving ever since their divergence. When a lineage branches off of the trunk of the main tree, it’s not like it is getting off a train and standing still while everyone else keeps moving through evolutionary space. “Basal” or “early-diverging” are much more accurate terms. Still, members of these groups have some features that we think were present in the first flowering plants, and we could call those features primitive – or more accurately, ancestral or plesiomorphic: most are woody, with simple leaves and simple unfused floral parts that are often neither sepal nor petal (so are called tepals). Think bay leaves and magnolia flowers. Some basal species make special cells packed with flavorful ethereal oils. These were not present in the very first flowering plants but apparently evolved fairly early, maybe 150 million years ago. Again, think bay leaves, sassafras, and star anise.
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