Zea mays belongs to the monocotyledon order of seed bearing plants (Angiosperms). Whereas dicotyledons have two cotyledons enclosed in the seed to provide initial nutrition to the embryo and often emerge to also produce more nutrition via photosynthesis, the single cotyledon of grasses such as corn, remain in the soil with the submerged seed. This cotyledon is called the scutellum. It is a thin, shield-like structure between the rest of the corn embryo and the endosperm. Its primary function is to absorb nutrients from the endosperm and transmit them to the growing embryo. Scutellum genetics are inherited with one set of chromosomes from each of the two parent plants. Mitochondria in the scutellum are inherited from the female parent.
Scutellum tissue is a storage tissue for the embryo, accumulating up to 90% of the kernel oil, 20% of protein and 10% of minerals. These become essential supplies for the germinating root and shoot.
Scutellum tissue is about 90% of the mass of a corn embryo, nearly surrounding the root and shoot growing points of a dormant corn seed. It is attached between these two growing points. A layer of scutellum cells adjacent to the endosperm, during germination, produce and secrete enzymes into endosperm, digesting the starch and proteins. Resulting sugars and amino acids are translocated to the embryo axis from which they are utilized for new cell development in the growing shoot and root tissue. Movement of these substances from the outer edge of the scutellum occurs through xylem and phloem that forms quickly when stimulated by moisture and heat for germination.
The dual functions of storing essential nutrients and digesting stored nutrients in the endosperm contribute the significant growth of roots and shoots as the newly germinating seedling pushes to the surface of the soil.
About Corn Journal
The purpose of this blog is to share perspectives of the biology of corn, its seed and diseases in a mix of technical and not so technical terms with all who are interested in this major crop. With more technical references to any of the topics easily available on the web with a search of key words, the blog will rarely cite references but will attempt to be accurate. Comments are welcome but will be screened before publishing. Comments and questions directed to the author by emails are encouraged.