5. Where stem ends/root begins difficult to see in embryo plantlet, but tip that will develop into the (embryo root). C. Monocot Seed Development (Ex. Corn plant) 1. Cotyledons do not play significant role in tood storage. 2 = bulk food storage 3. Plumule and radicle enclosed in tubular, sheathing structures called the 4. and i. Function: to protect delicate tissues within as seed germinates. 1. Once coleoptile and coleorhiza are a few millimeters long, they stop developing and plumule and radicle burst through tips:.