Most plant cells areÂ green due to the presence of chlorophyll, the pigment that traps sunlight, which the plant then uses as part of photosynthesis. Â But you can't always count on this to be true. Flower cells may contain red, orange and yellow pigments, and root cells may contain no colorful pigments at all. In this case, you can recognize a plant cell by its rigid cell wall and by the fact that it contains a fluid-filled space known as a vacuole.
Unlike animals, plants aren't able to excrete excess water, which means that sometimes the fluid pressure inside their cells gets pretty high. This is where the cell wall comes in--it prevents the cell from bursting.
See For Yourself
Another way the plant cell is adapted to the fact that it can't excrete waste is in the function of its vacuole, which it uses to store and recycle metabolic products into substances used for plant growth. The vacuole also contains other organic materials, such as some of the pigments that give flowers their color, and poisons to fend off predators.
If you're enjoying reading about plant cells, you might consider investing in a microscope toÂ get closeup view.
"Journey Into the Cell" at (About.com)
"Animal & Plant Cells" (Purchon.net)
"Plastids" at (McGraw Hill)