While we tend to think of trees and plants as being mostly the same, their inner machinery can be quite different from one another. This is because each tree has evolved a different strategy for sucking water out of the ground and into the canopy.
Oak trees have large xylem vessels, or water pipes, which allow them to slurp a lot of water at once. But if the oaks start drawing up water too early in the season, these big tubes put them at risk of freezing during a frost. If an oak tree’s vessel gets blocked by ice, it loses the ability to drink, said Haskell, who is the author of “The Songs of Trees” and “The Forest Unseen.”
Maple trees, on the other hand, have lots of tiny pipes, which don’t typically freeze. This means they can start moving water and doing other tree things, such as growing leaves, several weeks earlier in the spring than oaks.
Maple sap, which we turn into maple syrup, also acts a bit like an antifreeze, making sure the tree can survive even after a cold-weather snap — a common occurrence in early spring. But the oaks have a few tricks up their sleeves, or limbs, too.
Sunlight powers the tree’s plumbing, because it causes water to evaporate from the leaves, which in turn draws still more water out of the ground through the tree’s roots. And because oaks have relatively big water pipes, when that apparatus gets moving, Haskell says, it allows the tree to “feast on sunlight” during the energy-producing process of photosynthesis (pronounced fo-to-SIN-thuh-sis).“Oaks are champions of photosynthesis,” he says.
It’s a lot like Aesop’s fable of the tortoise and the hare, he said. Some plants are equipped to move quickly and start photosynthesizing early in the season, while others have to take a slower approach. And it’s the same trade-off for early-sprouting plants and flowers.
“What those wildflowers are doing is they have underground storage organs,” said Haskell. “And they can draw on those reserves to shoot up their flowers.”
This is how species such as spring beauties and snowdrops can pop up even when it’s still frigid outside — they’re using last year’s energy. And doing so allows them to take advantage of the sunlight that will disappear once all the trees sprout leaves and block the sun.
“In July, it’s actually darker on the forest floor than it is in January,” Haskell said.
So take a look around your neighborhood and see which plants are bare, flowering or full of leaves. Which plants are the tortoises, and which plants are the hares?
Bittel is a freelance journalist who often writes about animals. His new children’s book is “How to Talk to a Tiger . . . and Other Animals.”