ok, ok — so maybe they’re not really people, but they are pretty d*rn cool! no really!
bet ya didn’t know (or maybe you do) that they can tell if you’re wearing a red or a blue shirt. or that they know when the fruit of neighboring plants is ripe. or that they have short-term memory.
yes, short-term memory:
“As we saw back in chapter three, the Venus flytrap needs to know when an ideal meal is crawling across its leaves. Closing its trap requires a huge expense of energy, and reopening the trap can take several hours, so Dionaea only wants to spring closed when it’s sure that the dawdling insect visiting its surface is large enough to be worth its time. The large black hairs on their lobes allow the Venus flytraps to literally feel their prey, and they act as triggers that spring the trap closed when the proper prey makes its way across the trap. If the insect touches just one hair, the trap will not spring shut; but a large enough bug will likely touch two hairs within about twenty seconds, and that signal springs the Venus flytrap into action.
“We can look at this system as analogous to short-term memory. First, the flytrap encodes the information (forms the memory) that something (it doesn’t know what) has touched one of its hairs. Then it stores this information for a number of seconds (retains the memory) and finally retrieves this information (recalls the memory) once a second hair is touched. If a small ant takes a while to get from one hair to the next, the trap will have forgotten the first touch by the time the ant brushes up against the next hair. In other words, it loses the storage of the information, doesn’t close, and the ant happily meanders on. How does the plant encode and store the information from the unassuming bug’s encounter with the first hair? How does it remember the first touch in order to react upon the second…?
“In their [Dieter Hodick and Andreas Sievers] studies, they discovered that touching a trigger hair on the Venus flytrap causes an electric action potential that induces calcium channels to open in the trap (this coupling of action potentials and the opening of calcium channels is similar to the processes that occur during communication between human neurons), thus causing a rapid increase in the concentration of calcium ions.
“They proposed that the trap requires a relatively high concentration of calcium in order to close and that a single action potential from just one trigger hair being touched does not reach this level. Therefore, a second hair needs to be stimulated to push the calcium concentration over this threshold and spring the trap. The encoding of the information is in the initial rise in calcium levels. The retention of the information requires maintaining a high enough level of calcium so that a second increase (triggered by touching the second hair) pushes the total concentration of calcium over the threshold. As the calcium ion concentrations dissipate over time, if the second touch and potential don’t happen quickly, the final concentration after the second trigger won’t be high enough to close the trap, and the memory is lost….
“Here, then, lies the proposed mechanism of the short-term memory in the Venus flytrap. The first touch of a hair activates an electric potential that radiates from cell to cell. This electric charge is stored as an increase in ion concentrations for a short time until it dissipates within about twenty seconds. But if a second action potential reaches the midrib within this time, the cumulative charge and ion concentrations pass the threshold and the trap closes. If too much time elapses between action potentials, then the plant forgets the first one, and the trap stays open.
“This electric signal in the Venus flytrap (and the electric signals in other plants for that matter) are similar to the electric signals in neurons in humans and indeed all animals. The signal in both neurons and Dionaea leaves can be inhibited by drugs that block the ion channels which open in the membranes as the electric signal passes through the cell. When Volkov pretreated his plants with a chemical that inhibits potassium channels in human neurons, for example, the traps didn’t close when they were touched or when they received the electric charges.”
that’s from What a Plant Knows? A Field Guide to the Senses. if you’re looking for an easy but info-packed read to bring with you on your summer vacation, you could do a lot worse. i’m reading it right now (well, not right now) and it’s terrific! the book is by the author of The Daily Plant (heh) blog.
(note: comments do not require an email. my favorite plant!)