Asparagus is the edible shoot of a cultivated plant that rises from underground rhizomes (a type of stem) in early spring. It is closely related to the lily with more than 300 species.
Green and white asparagus are the same species that are grown differently but can be used interchangeably in recipes.
Ranging from pencil-thin to very thick, most American asparagus is of the green variety.
Preferred in Europe, white asparagus is a little milder and more tender than its green cousin. It is sometimes difficult to find fresh white asparagus in the States but it is widely available canned usually in jars.
So What's the Difference?
Dirt is kept mounded around the emerging stalk, or it is well covered, depriving it of light. Without light, the plant cannot produce chlorophyll, the naturally occurring chemical that turns the vegetable green, so there is no green color to the stalks.
Green asparagus, on the other hand, is left to grow uncovered so they can soak up all the sunlight they want, encouraging the chlorophyll to produce that vibrant green color they are associated with.