Now because I have a huge man-crush on Dawkins, and I would carry his half-ape half retarded fish babies, I have to mention Dawkin's views of kin selection. In writings on Kin Selection there are often references to Richard Dawkins’s article ‘12 Misunderstandings of Kin Selection’, in Zeitschrift für Tierpsychologie, 51 (1979), 184-200. Basically Dawkins doesn't think that kin selection is a special type of natural selection. He opposes the view that natural selection can be exerted on a group, since only the individual survives and reproduces and not a group. There is more to his arguments, but It's worth actually reading it.
So how does this relate to plants. Well kin selection is a complex process usually associated to social animals. Plants on the other hand, can't see, smell or move, or at least are limited in their ways to sense kinship. And if you can't recognize a kin, how can you have altruistic behavior? Now it's well known that when plants are in close proximity, they will exhibit more aggressive competitive behaviors, in order to secure resources. Rather than using its energy to grow or flower, it will allocate more to roots to cover larger areas. Now this group asked a simple question, will the plant be as competitive with its root system if the other plant in the pot is from the same species. Surprisingly it wasn't as agressive, suggesting it knows about the plants in its environment, but how? Anyways, I like this experiment because it would make for an awesome science-fair type experiment, or a good way to teach kids about evolution, kin selection
and natural selection.