Tag Archives: angiosperm

Origin stories: spices from the lowest branches of the tree

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. Continue reading

Pomegranates and the art of herbivore attraction

Jeanne walks you through the botany you need to know to understand pomegranate fruit structure.  Jeanne’s definition of “need to know” is arguably a bit broad and includes a brief tour of the many different structures plants modify in order to entice herbivores, and at least one goddess, to disperse seeds. 

pomegranate fruit (persistent calyx and stamens visible)

pomegranate fruit (persistent calyx and stamens visible)

Pomegranates (Punica granatum, family Lythraceae, rosid order Myrtales) were one of the earliest domesticated plant species.  According to ancient Greek mythology, they even predate the seasons.  The story goes that Hades, god of the underworld, kidnapped his beloved Persephone, daughter of Demeter, goddess of the harvest.  Demeter’s grief over Persephone’s disappearance caused the crops to wither and wreaked havoc with humanity.  The plight of the starving masses coerced Zeus to convince Hades to return Persephone to her mother.  Before she left the underworld, however, Hades tricked her into eating a pomegranate seed, which bound her to evermore spend part of the year with her happy mother, during which time plants flourished, and part of the year in the underworld, during which time plants go fallow. Thus, seasons arose.

Pomegranate seeds

Pomegranate seeds

We can hardly blame poor Persephone for finding pomegranate seeds irresistible.  They look like faceted jewels and have a refreshing, tangy sweetness and a satisfying crunch. We have an additional reason to be drawn to pomegranates: even if they can’t help us understand the seasons, deciphering the structures of the beautiful pomegranate fruit helps us understand the diversity of mechanisms plants use to entice animals, including humans, to disperse seeds.  The delicious, nutritious or fibrous attractive structure is payment for the animal’s labor. As you will see in this post, there is no single anatomical recipe for creating the colorful, fleshy and/or juicy reward for a seed-dispersing herbivore, mortal or otherwise.  Many of the myriad flower, fruit and seed structures are variously promoted to the role of what is colloquially thought of as “fruit.” Continue reading

Welcome to 2013, the International Year of Quinoa

Can we call quinoa a grain? Why do people care?  Where did all these geese feet come from, and what does Ban Ki-moon have to do with it?  On long winter runs, Katherine’s mind wanders over such questions.

Quinoa seeds (Chenopodium quinoa)

Quinoa seeds (Chenopodium quinoa)

In the final two months of 2012, questions about quinoa and its status as a “grain” came up three separate times within my earshot.  This was odd in itself, but it launched a cascade of coincidences.  On a run near the baylands, my mind was idling back over those conversations, when I noticed for the first time a little weed along the trail, looking much like one of quinoa’s relatives, a saltbush.  (The crushed specimen I carried home in my shoe laces keyed out as Atriplex semibaccata, Australian saltbush.)  There is also a gorgeous and much larger saltbush species along the trail, and yet another relative, an edible Salicornia species (“sea beans”) that fills the marshy areas next to the bay.  Along with quinoa, spinach, beets, and chard, all of these species belong to the (former) goosefoot family – the Chenopodiaceae – which is now considered a branch nested within the Amaranth family.  Quinoa is a central member of this old family, belonging in the namesake genus Chenopodium. Continue reading

The extraordinary diversity of Brassica oleracea

Before the caterpillars attacked: Red Russian kale seedlings

Jeanne turns her frustration with caterpillars in her garden into an exploration of the botany behind an extraordinary species:  Brassica oleracea.

White cabbage butterflies (Lepidoptera: Pieris rapae) decimated the fall kale crop in our garden.  To be fair, the abundant green caterpillars did not consume the entire blade of every leaf.  The remaining nibbled leaves, however, in my husband’s view, no longer resembled food so much as a caterpillar farm that would be tedious to turn into food.  He ripped out the caterpillar farm, threw it on the compost bin, and replaced it with lettuce.  Unlike kale, which is in the mustard family (Brassicaceae), lettuce is in the sunflower family (Asteraceae) and is therefore not even remotely attractive to white cabbage butterflies.

Caterpillar damage on young green curly kale in the garden at Monticello

I was tempted to save the hole-riddled leaves from their compost fate, in part because I know that the munching of the caterpillars actually increased the foliar concentration of some of the compounds that contribute to kale’s nutritious reputation, and also because plummeting autumn temperatures impart an extraordinary sweetness to kale and the other cruciferous vegetables that are all actually varieties of the same species, Brassica oleracea: cauliflower, cabbage, kohlrabi, Brussels sprouts, Chinese broccoli, and collard greens.  The details of the chemical consequences of caterpillar consumption will soon get a post all their own.  This post is dedicated to the botany and evolutionary biology behind the amazing diversity of B. oleracea. Continue reading

Varieties of the pepper experience

Chili, black pepper, white pepper, and Sichuan pepper

Black pepper, pink peppercorns, chili pepper, Sichuan pepper – except for being “hot,” these spices have as little in common as Sergeant Pepper and Pepper Potts.  Their homelands are scattered across the world, and they were spread through distinct trade routes.  They are not closely related; they belong to families about as far apart as possible on the phylogenetic tree below.  They even aim their heat at different sensory receptors in your mouth. Continue reading