What is a cleistogamous flower?

Cleistogamy means the formation of flowers that do not open. The production of seeds in cleistogamous flowers is a result of autogamy. Cleistogamous flowers do not open at all. Because anthers and stigma are not exposed. Cross pollination cannot take place in such cases. Examples are Viola mirabilis and Oxalis acetosella .

What is fertilization? Explain the double fertilization in the angiospermic plant with labelled diagram.

Fertilization is the important step in sexual reproduction in which the male gamete or sperm and female gamete or egg are fused together to form a zygote. This process is also called syngamy. The zygote is the first diploid cell of an organism. After fertilization, the zygote develops to form an embryo. In angiosperms, two acts of fertilization occur in the same embryo sac. In the fertilization processes, each pollen grain or male gametophyte releases two male gametes into the embryo sac of the ovule. Out of the two male gametes, one fuses with the egg (female gamete) to form a diploid zygote. It is called syngamy or generative fertilization. Another male gamete fuses with polar nuclei or secondary nucleus (formed by the fusion of polar nuclei) to form a triploid primary endosperm nucleus. This process is called triple fusion or vegetative fertilization. Since two kinds of fusion that is syngamy and triple fusion take place in the flowering plants, the process is known as double fertilization. In double fertilization, two male gametes, one egg cell, and two polar nuclei or one secondary nucleus are involved. Among these male gametes and female gamete (egg) are haploid cells. Two polar nuclei are also haploid structure but these are often fused to form a diploid secondary nucleus. The products of double fertilization are a diploid zygote and a triploid primary endosperm nucleus.

What is the difference between phellem and phelloderm.

Feature Phellem Phelloderm Location It is a tissue formed on the outer side of phellogen, also called cork cambium. It is a tissue formed on the inner side of the cork cambium. Feature Phellem Phelloderm Function It is made of dead cells and has protective functions. It is made of living cells and is involved in the storage of food.