Knowledge about plants that can cure or kill has been prized, and feared, for centuries.
Flip through an enchanted botanical book and learn the history and mythology of many poisonous plant species.
What is this sorcery? That book is some straight Harry Potter business. You should really go flip through it, though. Well done.
I wonder … what does it take for a plant to be poisonous? As Paracelsus said:
All things are poison, and nothing is without poison; only the dose permits something not to be poisonous.
That a plant is medicinal, poisonous, or just plain delicious/nutritious is up to the mouth that mascerates it, so to speak.
I think we discussed this a while back, but it seems like nature has a general rule about bitter things being a universal sign of “No, no, you don’t want this." I haven’t studied it deeply enough to make a blanket statement, but consider the following:
Whether it’s the bitter compounds of coffee beans (which also contain the potent insect neurotoxin/human stimulant we call “caffeine”), or any number of bitter leafy greens (whose compounds are meant to discourage feeding bugs), where we find plants producing bitter we find plants begging “Please … please no, please go do something else, I’m gross and bad for you.”
Botany fans, what interesting cases do you know of where we consume a plant for food or medicine, while other creatures would treat it like a box of rat poison?
I’m Pollen For You
It’s a lot prettier when it’s on paper rather than launching your sinuses into full revolt and unleashing a Niagara Falls-level torrent of snotty discomfort, eh?
Pollen is strange stuff. Although many pollen grains are only a few millionths of a meter across, plants sculpt remarkably intricate and diverse suits of armor for these mobile gametes, having evolved a remarkable variation of symmetries.
To deliver a plant’s male genetic material to female plant parts, it’s got to be both sticky and tough. Within the pollen grain, a dormant cell lies poised for division, ready to burrow a pollen tube toward the seed ovum when it finds the right female parts. Surrounding that hibernating genetic material are two layers of protection: cellulose-rich intine and sporopollenin-sculpted exine.
So tough are those outer layers, so effectively do they protect the cells within, that pollen grains can be used to study everything from crime scenes to ancient climates. The spores below have survived more than 400 million years, dating from a time when plants had just invaded land and begun to reach up toward the sun:
Illustrations up top are from Ueber de Pollen, by Carl Julius Fritzsche (1837). If you speak German, there’s more small wonder for you here.
(via Public Domain Review)
The first person to slice open a plant stem and view it under a microscope must have been rightly confused.
These days every kindergartner can grasp the basic architecture of a plant. Probably thanks to celery sticks, come to think of it, dipped in colored water, transporting the dyes up their stalk. We’ve all been there, right? It’s thanks to xylem and phloem, that intricate biological plumbing cool enough to make Roman aqueduct engineers jealous. But in the mid-17th century, when men were just beginning to point their telescopes down from the sky toward the micro-universe, the inside of a plant must have been quite a wondrous shock.
Nehemiah Grew was one of those 17th century explorers, unlocking new tiny worlds (joining men like Hooke and van Leeuwenhoek). He had great hair, to go with great curiosity, which he applied to fields ranging from philosophy to science (the curiosity, not the hair). There were fewer boundaries around the subjects people studied back then. I think we should get back to that. Anyway …
Grew approached plant anatomy with the belief that all living things were built and organized from similar ingredients, and from a similar toolbox. Our organs, our fluids, all had a mirror in the plant world, and vice versa. He wasn’t totally right about that, but he wasn’t totally off either (although it would take the dawn of genetics before we really appreciated the details).
Nehemiah Grew’s 1682 work The Anatomy of Plants secured his place as the father of plant anatomy. Public Domain Review has a superb look at his philosophy and science, and the early plant illustrations that helped our knowledge grow. Or Grew.
In this interesting close-up by Dietmut Teijgeman-Hansen, we see what remains of a leaf that was likely consumed by an insect and is now slowly decomposing. According to reddit’s resident biologist Unidan:
“The reason this skeletal like pattern remains in the leaves is due to higher concentrations of lignin (a strong carbon structural molecule that is what makes wood woody) in the tracheid xylem cells. The more easily decomposed cells will rot away (or be eaten away, as it is more nutritious and more easily digested by insects), leaving the tougher skeletal lignin frame”
Plants and people, we all leaf bones behind. They become us in life, we become them in death.
Seasons Come and Seasons Glow
We’ve all eaten more than our fill, especially during this time of year. Did you know plants can get full, too?
The elaborate process of converting sunlight into usable energy (the so-called “light reactions” or “magic”) is essentially a big chain where one protein hands off electrons to the next in order to break apart water and build up a bunch of hydrogen ions that can be used to power the ATP factory:
It’s a bit like someone carrying buckets of water upriver in order to power the water wheel at the old mill. The thing is, any a given chloroplast can only hold and process so much sun energy at one time. In order to prevent damage to the leaf factory, the plant gets rid of the excess, either via heat or by giving off light.
That’s right, plants can glow! Or more accurately, chlorophyll can fluoresce. And they do it just about any time they are undergoing photosynthesis, it’s just that we can’t see it. But NASA can. Their Earth-observing satellites can detect this excess plant energy and use it to check how active and healthy our planet’s vegetation is.
The above visualization from NASA shows four years worth of plant fluorescence, averaged into one complete seasonal cycle. Winter turns to spring, spring to summer, and autumn leaves fall, played out in waves of glowing pink.
Previously: The world viewed through Kodak’s Aerochrome film … pink plants everywhere!
Green, yellow,and red, oh my! What causes the beautiful autumn colors and why do leaves need to fall off anyways?
A little pigment called chlorophyll and a little bug called an aphid have a lot to do with it.
I’ve heard this happens in other parts of the country. I’ll take Julia’s word for it. Good to know the science, anyhow, just in case I stumble upon it and am confused by orange-hued trees.
Scientists study the effects of light on plant life cycles in Beltsville, Maryland, August 1953.Photograph by Jack Fletcher, National Geographic
Let’s play a little thought exercise: Which color(s) of light do you think would be better/worse for plant growth? What makes you think that?
Please show your work, and everyone gets an A+ just for trying.
NASA Sees Photosynthesis From Space
Plants are often unable to absorb all the light that hits their leaves and chloroplasts. A small portion is re-emitted as fluorescence, it’s just that we can’t see the faint signal in broad daylight.
But satellites can. NASA shows you what plant fluorescence looks like from orbit. This kind of data is key to understanding the health of global vegetation.