Tag: kingdom plantae

Azolla is extensively grown in rice paddies to increase rice production by more than to 50%. Nitrogen is the single most limiting factor in rice cultivation, strongly affecting the crop yield. Azolla substantially increases the amount of nitrogen fertiliser available to growing rice and it is has been used for thousands of years as a green nitrogen fertiliser to increase rice production.

The correct answer is 'lycopsida'

Rhizophores is a  structure of controversial morphological nature.They are leafless and  positively geotropic organs that have localised origin and develop from angle meristems. Goebel and Bower considered them as Organs sui generis (i.e.,neither roots or shoots). According to J.C.Shoute,Organ sui generis is one that is a novelty and has not arisen as result of  metamorphosis of any organ.

Heteromorphic alternation of generation means a sporophytic phase and gametophytic phase alternate each other. Eg: Dryopteris

In Dryopteris sori, a group of sporangia covered with indusium are present along the margin of pinnae or leaflets. In it 2-8 sori are borne on the abaxial surface of the mature fronds (sporophylls). They are situated in two rows at the tips of the veinlets in between the midrib and the margins. The sori appear reniform due to the kidney shaped protective thin and membranous covering, called as indusium.

In Pteridophyte Dryopteris the gametophytes give rise to sporophyte by gametic union and sporophyte gives rise to gametophyte by forming haploid spores after meiosis. 

The multiflagellated antherozoids of Dryopteris, point out that they originated from aquatic ancestors. In auatic environment the multiflagellated antherozoids swim in the water and fertilize the egg. Water is necessary for the fertilisation process. It proves their aquatic ancestry.

The polycyclic condition is the most complex of stelar organization found among pteridophytes. It is a dictyostele consisting of two or more concentric rings of meristeles. It occurs in Pteridium sp. 

Young sporophyte of Pteris draws nourishment from the foot. Foot is formed first, which absorbs water, minerals from prothallus. Prothallium, or prothallus is usually the gametophyte stage in the life of a fern or other pteridophyte. The prothallium develops from a germinating spore. It is a short-lived and inconspicuous heart-shaped structure typically 2-5 millimeters wide, with a number of rhizoids (root-like hairs) growing underneath, and the sex organs: archegonium (female) and antheridium (male). Appearance varies quite a lot between species. Some are green and conduct photosynthesis, while others are colorless and nourish themselves underground as saprotrophs.