morphology of plants

ROOTS- Roots arise from parts of plant other than radicle are called adventitious roots. E.g. grass, banyan tree.- Regions of root        - root at the apex is covered by a thimble like structure called as root cap, and the root cap protects the tender apex as it makes its way through the soil.        -region of meristematic activity: the region is very small, thin walled with dense protoplasm. They divide repeatedly.        -region of elongation: this area undergoes rapid elongation and enlargement and are responsible for the growth of the root in length.        -region of maturation: cells of the elongation zone differentiate and mature and form dis zone.-MODIFICATION OF ROOT           -food storage: E.g. sweet potato, radish, carrot        -support:   -prop roots: arise from branches E.g. banyan tree                          -stilt roots : arise from lower nodes of the stem E.g. maize, sugar cane         -respiration: in plants living in swampy areas root grow vertically upwards and help to get O2 E.g. pneumatophores - rhizophoraLEAF- In some leguminous plants the leaf base may be swollen and is called pulvinus .- The arrangement of veins and veinlet's in the lamina of leaf is known as venation.        -when the veinlet's form a network the venation is termed as reticulate         - when the veins run parallel to the lamina the venation is termed as parallel.        - dicot plants reticulate venation and monocot plants parallel venation.-simple leaves: a leaf having a single or undivided lamina  compound leaves : when the divisions of the leaf touch the midrib                      pinnate: feather like outline bear leaves on the common rachis and leaflets occur in two lateral rows                      palmate: palm like outline the leaflet joining point represents tip of the petiole and all leaflets are clustered together.-                                                        

New Page