David N. Snyder wrote:According to the Buddhist cosmology rebirth can be to humans, animals, devas and other celestial beings, but not plants.
There is no violation to eating or 'killing' a plant in Buddhism. There is a Vinaya rule that prohibits monks and nuns from harming plants, but this probably has more to do with not harming the environment in general or looking unseemly to lay people.
Also don't forget preta (or ghosts/spirits)!
With the Vinaya rule on harming plants, I understand that the Buddha once said any plants at least 3 feet tall (or some other measurement units) can house a spirit. If you cut down such a plant, you would be effectively destroying the spirit's home. Hence, for compassion reason, Bhikṣu and Bhikṣuṇī are to not harm trees.
Ven. Chin Kung told a story that once in Australia their Buddhist group had to arrange for a tree to be cut down to build a temple. They, following the Buddha's teaching, read sutra to the tree spirit and asked it to move in three days, after which they will cut down the tree. Therefore there are ways for devoted Buddhist to deal with those situations.
Now if you are interested in the rest of Ven. Chin Kung's story, here is what happened... That night one of the monks had a dream where the tree spirit complained that three days was too short, and they should have given seven days of notice! Ven. Chin Kung's theory is that Australian people had an easier pace to doing things, so the same goes for spirits in Australia
Video at http://www.youtube.com/watch?v=KI_cf4LCjKU
but it is in Chinese only.