Dicotyledonous seed:
Gram, pea, castor and beans are main dicotyledon seeds, contains two cotyledons as store food which requires during germination of seed. A typical dicotyledon seed has following structures in it
- Seed coat
- Embryo
- Endosperm
1. Seed coat: Seed coat of a seed has two sub layers. The outer one is though, hard which may be of different colours called as testa. Inner layer of seed coat is called as tegmen which is comparatively thin and white in colour. Every seed has a small pore opening in it which called as micropyle, near to micropyle a scar is also observed which is called as hilum. Hilum is the place where a seed remain attach with fruit.
2. Embryo: Every dicotyledon seed has a embryonal axis beneath seed coat. One end of embryonal axis is called as Plumule and other end is called Radicle. Plumule forms shoot while radicle forms root during germination of seed.
3. Endosprem: Endosperm is food storage site which forms after double fertilization of central cell of ovule.
When endosperm is consumed during development of zygote into the embryo then in seed endosperm is absent but when endosperm not consumed completely then it is present in seed also. In gram, pea and beans endospenn is present in initial stage of seed but later on it is consumed so mature seeds do not have endosperm in it. These seed are non endospermic seeds but in castor seed fleshy endosperm is present in mature seed so it is called as endospermic seed
