Do all plants react the same when over-crowded?

Question

Corn is ALWAYS grow together and they never die. Grass too, is always grown together and never dies. So, it there another plant that won't die when overcrowded? Do you guys know any plants that will die if there is even, 2 plants in the same pot?

Answer 1

Overcrowded plants will not grow and produce properly when they lack adequate space. They will compete for space and light, thus stretching and not concentrating their energy on flowering and fruiting. Plants stressed in this way are usually more susceptible to plant diseases and insect damage because crowded foliage provides an environment that protects them in their early development.
http://www.planetnatural.com/site/xdpy/kb/greenhouse-success.html

Corn is not expected to grow for more than one season. Even then, they need to be spaced properly or suffer from a nutrient competition problem... since corn is a heavy consumer of nitrogen.
http://forums.gardenweb.com/forums/load/sqfoot/msg0119311810939.html

Clover planted with grass actually helps provide nutrients to the grass, so they can grow close enough together that they look overcrowded. "Clover snatches nitrogen out of the air, bringing this most essential fertilizer "down-to-earth" by means of nitrogen-fixing bacteria living in nodes along the roots."Grass will reseed itself if some of it dies.
http://landscaping.about.com/cs/lawns/a/clover_lawns_4.htm

If a pot is too small for more than one plant, two plants will be overcrowded & this can lead to one or both plants dying.

Answer 2

I like my gardens crowded and never have a problem. BUT if you have a shrub that is taller then the flower plants, the shrub will shade the flowers and keep them from getting sunshine. Here are two pictures of crowding:

http://www.kriyayoga.com/philippines/baguio_city_philippines/flower_gardens/tropical_garden_flowers.jpg

http://www.flower-garden-bulbs.com/images/spring-flower-bulbs.jpg