Tag: angiosperms

Dalbergia sissoo, known commonly as Indian rosewood, is an evergreen rosewood tree, also known as sisu, sheesham, tahli, Tali and also Irugudujava. It is native to the Indian Subcontinent and Southern Iran. In Persian, it is called as Jag. Shisham is best known internationally as a premier timber species of the rosewood genus, but is also used as fuel wood and for shade and shelter. With its multiple products and tolerance of light frosts and long dry seasons, this species deserves greater consideration for tree farming, reforestation and agro forestry applications. After teak, it is the most important cultivated timber tree of Bihar, which is the largest producer of shisham timber in India.
Acacia arabica (thorn tree), Mangifera indica (mango) and Prosopis (SW) dc are not timber yielding trees. 
Therefore, the correct answer is option B.

Archegonia are multicellular organs found during the gametophytic phase of the plants and contains ovum. With a  long neck canal or venter and a swollen base these are either found on the surface of the plant or are embedded. However, in case of Angiosperms, there is no archegonia and the megagametophyte is reduced to just a few cells, one of which differentiates into the egg cell are contained in the ovule and enclosed in the megasporophyll or carpel.

Double fertilization refers to the complex fertilization mechanism of flowering plants. Being a charasterisitcs of all Angiosperms, each pollen grain produces two sperms, where one fuses with an egg to form the zygote, and the other fuses with polar nuclei in the female gametophyte (megagametophyte, or the embryo sac) to form an endosperm. The process in which both nuclei from the pollen tube fuse is referred to as double fertilization.

Angiosperms are most diverse and widespread of all plant groups. Their dominance is due to the power of adaptability in diverse habitat. They are well adapted to terrestrial life and occur in diverse habitats like cold tundra to hot tropical and even desert areas. They also thrive well in the aquatic habitat. Therefore, they being the most successful to have dominated the land flora. Hence option B is correct.