It just turns orange as it ripens, which also shows when the pumpkin is ready to be picked. There isn't really a reason why vegetables/fruits turn colors. It is just the natural color they turn when they ripen.
It is the color that they really are in the absence of chlorophyll (food) for the pumpkin to grow. Chloraphyll is green so when the plant stops producing food for the pumpkin to grow, the pumpkin turns orange.
Pumpkin color is nothing but a 'greyed' or toned down orange. Try mixing a little blue into the orange.
brown
A pumpkin spider, or an orange orb-weaver spider.
a pumpkin is orange and a pumpkin while a shrub is not....
Because the pumpkin is huge
pumpkin
Pumpkin!
pretty much the same only smaller and green
Since pumpkin is like orange, and orange and blue are complementary colors, the likely result is brown.
The orange color of a pumpkin is caused by the same chemical that makes carrots orange, which is called carotene. This is a nutritious substance which human beings use to make vitamin A.
light orange (yellowy)
Pumpkin is a shade of orange that is commonly associated with pumpkins, it is also the name of an Anything Muppet pattern (the tall kind with the oval head)
Pumpkins are definitely orange. When you see one, you will know its a pumpkin!