If a plant needs more sunlight, it grows towards the sun. If it needs water, it's roots grow towards the water. Climbing vines even search for objects to climb! Much of this behavior is documented by the videos found at the Plants-In-Motion website, maintained by Roger Hangarter at Indiana University. I cannot embed these videos here (though I have found some that are on YouTube), so you'll have to go to his site to see the following behavior/growth patterns.
Let's start with the basics:
- Corn (maize) germination: Notice that the seeds can tell "up" from "down" (called gravitropism).
- Sunflower dark and light: The seedlings know when they've reached the sunlight (called photomorhogenesis).
- Corn seedlings bending towards a lone lightbulb (phototropism).
Even after they've gotten big, plants continue to grow and respond to the above environmental cues (for instance, if the get knocked over). However, they also have more sophisticated behaviors. Some of these happen more quickly and do not involve growth.
- Sunflower leaves tracking the sun (heliotropism), and even preparing for sunrise (circadian rhythm).
- Morning glory vine seeking a pole to grow on (twining).
- Arabidopsis seedlings waving back and forth (nutation).
- Finally, there's the classic "sensitive plant", which will curl up at your touch.
Another good collection comes from ChloroFilms, which hosts contests for the production of plant videos. The current crop of videos (round 2) has a lot of carnivorous plants, which are sure to catch your attention. Here's a video of the venus-fly trap in action:
Other videos range from ecology to some of the more technical aspects of plant research, including how to prepare tissue cultures, depiction of mutants, and how to hand pollinate flowers. Prize-winning videos from the first competition include a sex-ed video for plants, and some fluorescent microscopy of vesicle movement in root hairs. See here:
ChloroFilms is is collecting submissions for additional films, so if you can get something together in two weeks (April 15), give it a shot! If it will take you a little longer to make a video, maybe they'll hold another competition (though I don't know what they get from it).
While we're talking about competitions, check out my submission to the Scientific Blogging science writing competition: "What would cast doubt on evolution? Spontaneous generation" Please cast a vote if you like it.