I was recently thinking about how absolutely astounding, evolutionarily-speaking, vascular plants are. Like, OK, there's the meme/true statement/"fun fact" that occasionally goes around about how "sharks are older than trees," and the thing you're supposed to take home about it is that sharks are really, really fucking ancient, and therefore badass. And, yeah, that's true. But one should also pause and stop and be amazed at how incredibly advanced and recent and weird and sophisticated trees - and, in fact, all vascular plants - are.
Allow me to digress. Complex ecosystems on earth are fundamentally oceanic. Regardless of where life originated, it first became really sophisticated, as far as we can tell, in the oceans. There were hundreds of millions of years when the oceans where full of complex food webs and large, multicellular organisms, and the land was at least as barren as the north coast of Ellesmere Island is today. And in the ocean, the food chain is indeed a chain, in the sense that an 18th century scholar thoroughly wedded to the idea of the "great chain of being" would understand. Primary producers are simple in organization, and as you move "up" the food chain, things become progressively more complex. There are exceptions, but in general the food chain moves from structurally simple phytoplankton up and up and up, through zooplankton and cnidarians and sponges and tunicates and etc., before finally ending up in such gigantic, sophisticated, highly mobile, intelligent and agentic animals as architeuthids and cetaceans.
Now imagine if some sapient, scientifically sophisticated species on some waterworld - dwelling beneath the ice on Europa, for instance - were to imagine life outside of the ocean. Let's call them "Euroctopodes." Obviously, there would need to be primary producers, and after much debate our Euroctopodes would reject the idea of these "sky algae" floating around indefinitely in so thin a fluid as air. Instead, I believe that they might imagine something much like, well, the south coast of Ellesmere Island. A world where something like lichen is the primary producer - some low growth, huddling near the earth, a unicellular symbiont corralled by some only marginally more elaborate* structure-producing multicellular organism. And upon this simple base, a vast superstructure is erected, ending in vast herds of something recognizably equivalent to reindeer and muskoxen, preyed upon by something recognizably equivalent to wolves and bears.
This is the view from first principals, from a world without vascular plants. But, instead, what do we see? Under the water, there are coral reefs and kelp forests, sure, but they are scattered, dependent on unusual conditions. Above the waves? Forests. Grasslands. Savannahs. Jungles. Maquises and chapparals. Swamps, fens, and marshes. Everywhere you go, the primary producers - vascular plants - are giant and omnipresent and visibly dominant. They are structurally complex, they are elaborate, they dominate vast, seemingly unbounded volumes of space, they are elaborate in sexual display, they are gigantic, they are everywhere. The land is so much smaller than the sea, and yet describe the rolling Nebraskan prairie or the dense Brazilian rainforest or the Russian taiga to a Euroctopus, used only to scattered reefs and pseudowhale-falls and hydrothermal vents. Imagine describing the "green tunnel" of the Appalachian trail - 2,000 miles where the three dimensional view of a megafaunal species like a human is dominated in all directions by primary producers that tower over him. There never was a kelp "forest" so vast!
I guess what I'm saying is: the physical and physiological constraints that led to the evolution of vascular plants are well and rigorously documented in the scientific literature of botany and of evolutionary biology. We know well what challenges plants faced when they first began to spread on to land, and we know how logical and sound were the methods by which evolution winnowed them into their current forms. But I feel we need to appreciate what an incredible, unexpected triumph these final forms are; what an unbelievable 400 million years it's been for the lineage that has brought forth the daisy, the mahogany, the ginkgo, the cactus, and the wheat.
To bring this back to my ostensible theme of "pure americanism," we may count the vascular plants as the first Americans, since they were the first to Turn the World Upside-Down.
* man, zero offense to lichens or lichenologists or mycologists here. lichens are some of my favorite little guys, i love them so much, but if you can pause and appreciate that the difference between a jellyfish and a sperm whale is not purely subjective, i think you can also pause and admit the same about the difference between a Cladonia and a royal palm. and if you can find a way to word this more precisely, i'm open to it.
