Hollow Crown (Guernsey, Student, Ideal)  The principal variety it has roots 9 to 11 inches long and 2 1/4 to 3 inches in diameter at shoulder and 1 3/4 inches at the throat.  The Parsnip is creamy, crisp, brittle fleshed, hollow crown, occasional ridges with a few scattered side roots.  The dark green tops can reach 18 to 24 inches tall. Other varieties include Improved Half Long, Long Smooth, Short Thick, Smooth White, All American and White Model