What is the function of the cotyledon in monocot seeds?
I assume that monocots have hypogeal germination. Why are cotyledons present at all in seeds which undergo hypogeal germination? The cotyledon in monocots is represented by a structure called the “scutellum” and is an outgrowth of the embryo. The scutellum is connected to the embryo by vascular tissue. The scutellum is right up against the endosperm. When germination is initiated, the embryo starts to secrete gibberellic acid (GA). After 24 hours the scutellum also starts to synthesise GA. The GA triggers synthesis of various enzymes by the aleurone layer (just under the pericarp/testa). These enzymes (including alpha-amylase) enable mobilisation of the endosperm and the products are absorbed by the scutellum and passed to the developing embryo. In the light of the above, I believe all monocots will have hypogeal germination. In non-endospermic seeds the cotyledons are the food store. The function of the cotyledon/scutellum in monocots is to a) synthesise GA and b) absorb the digested
