Classificationof seeds based on embryo biology biologydiscussion
Answers
Explanation:
Meaning of Seeds:
Seed is the name of a ripened ovule which contains an embryo or miniature plant in suspended animation, adequate reserve food for future development of the embryo and a covering for protection against mechanical injury, loss of water, pathogens, etc. A seed may have one or two coverings called seed coats. The outer or the only seed coat (if one is present) is called testa while the inner one is named as tegmen.
The surface of the seed possesses a fine pore at one end. It is called micro Pyle. There is also a scar called hilum. It is the place where funiculus or stalk of the seed is borne.
Some seeds also show chalaza (place of origin of seed coats) and raphe (part of funiculus fused with seed wall). The embryo consists of an axis or tigellum to which are attached one (in monocotyledonous seeds) or two (in dicotyledonous seeds) seed leaves or cotyledons.
The place of attachment of cotyledons on the embryo axis is called cotyledonary node. Micro pyler end of tigellum bears radicle or embryonic root. The other end contains plumule or embryonic bud. The part of embryo axis or tigellum between the radicle and cotyledonary node is known as hypocotyl while the one between plumule and cotyledonary node is called epicotyl.
Food storing tissue of a seed is endosperm. In flowering plants it is produced as a result of double fertilization. In most monocots and some dicot seeds, the food reserve remains in the endosperm. They are called endospermic or albuminous seeds, e.g., cereals, caster Bean, Coconuts, Rubber.
However, the majority of dicot seeds (e.g., Pea, Gram, Bean, Mustard, and Groundnut) and a some monocot seeds (e.g., Orchids, Sagittaria), the endosperm is consumed during seed development and the food is stored in cotyledons and other regions.