What purpose does caffeine serve for the plant that produces it?

Why do coffee and tea and other plants produce caffeine? What benefit does it give the plant, or what chemical life-function does it perform?

If scientists were to knock out the gene that produces caffeine, would the plant survive?

The plant might survive, but I sure wouldn’t. You do not want to see me in the morning before my two cups of coffee. Not a pretty sight.

{{{Why do coffee and tea and other plants produce caffeine?}}}—Revtim

To make men happy! Oops! Sorry, that’s the answer to the boobs question.

Possibly, it’s a protection mechanism?

(The Original EnigmaOne)

The jungles of Columbia are very boring. The plant is simply trying to keep itself awake.

Most chemicals like caffeine, nicotine, and the like (termed alkaloids) are hypothesized to serve a defensive function for the plant. The plant is able to make a substantial dose of these nasties, and if you’re a relatively small herbivore, consuming a large quantity of the seeds, leaves, stems, etc… that contain these chemicals would probably make you sick, or worse kill you. If you, as a small herbivore, simply got sick from eating the offending plant part then you might learn that whatever you ate made you sick, and not do it again; thus enabling the plant to live and reproduce. This is not to mention that most alkaloids are pretty bitter to begin with, and this may serve as an initial feeding deterent. Whew!

If you are not part of the solution,
your part of the precipitate.

You guys sick of me citing EB yet? Good. I get the service for free. Might as well exploit it:

Morphine, strychnine, quinine, and ephedrine are also alkaloids.

Caffeine, nicotine and other related drugs serve the purpose of killing hungry insects. Insects’ tolerance for these types of chemicals is very low. Small amounts make many insects throw up right away, and those that manage to stomach larger amounts die soon afterwards.

  • Think of it this way; if you walk through a forest or any other natural outdoor setting where plants are present, all of the plants present produce chemicals to keep insects and animals from eating them. The chemicals can be merely noxious, or may be lethal. That’s why you can’t eat Maple tree leaves, and also why you don’t often see garden vegetables growing wild - the toxins have been bred down to make them more palatable, but the problem is that insects and animals like them more also. If you took a potted tomato plant and set it in the middle of the woods, insects and animals would make quick work of it while ignoring the regular plants all around it.
  • If you could remove the plant’s ability to produce caffiene, it most likely wouldn’t survive in the wild anymore. Many plants produce detectable amounts of caffeine, nicotine and other stimulants but for tea and tobacco, that’s the main defense. It’s just pure chance that it’s useful to us peoples. - MC
  • Dammit! When I looked at this thread, there were two lousy posts! - MC

Funny how many plant defense mechanisms we subvert for our pleasure. Caffeine, nicotine, capsaicin (the hot stuff in peppers).

It’s so the plant can get up in the morning glory. Just like poppies have opium, so they can sleep in the night blooming jasmine.

Signitorily yours, Mr John
" Pardon me while I have a strange interlude."-Marx

Yes, funny :). Nicoteine BTW is a very toxic poison (well for insects at least). Theres recipes for insecticide by making a “tea” from cigarettes. Most gardeners warn against using it though (and it does have that ugly yellow brown color too). Capsaicin has an effect on mammals, but with birds it doesnt even phase them.

side question, and i’m sure this has been discussed before. Caffeine, Ephedrine, speed, and nicotine are all stimulants… so why is it that caffeine and ephedrine (and i suppose speed, although i’ve never had it) make you all hyper and energetic, while nicotine relaxes you and can even give you a buzz, sorta like alcohol - a depressant?


I routinely get a “buzz” from caffeine. Of course, it takes a fairly large amount of the stuff to have that effect, and I consume a lot more it than your average person does.

Don’t forget - some alkaloids serve the purpose of attracting beneficial critters (typically serving pollination), or repelling all but the beneficial ones which developed a tolerance. This of course leads to a chicken-or-the-egg-first debate.

Unless you include viruses (tobacco mosaic), don’t recall that these examples fall in this category though.

“Proverbs for Paranoids, 1: You may never get to touch the Master, but you can tickle his creatures.”

  • T.Pynchon, Gravity’s Rainbow.

Kalt: Nicotine doesn’t actually cause you to relax. Any feelings of relaxation are caused by a relief of withdrawal symptoms that you were feeling. (or something like that. Source: HS health teacher long, long ago. Reliability: ???)

I always figured the relaxation came from taking about five minutes, sitting down away from whatever was stress-inducing, and breathing deeply. The smoke has nothing to do with it. :wink:


I’ve seen pictures of spider webs produced by spiders doped up on various compounds. The “caffeine” web wasn’t as wild as some of the others, but it was clearly different from (and pretty obviously inferior to) the “normal” control web.