Differences between Gymnosperms and Pteridophytes .

Differences between Gymnosperms and Pteridophytes . 

The plant bodies of pteridophytes are provided with well developed true roots , stems and leaves . They possess vascular or conducting tissues such as xylem and phloem and so they are known as vascular cryptogams. They never produced seeds at all. The plant bodies of gymnosperms are provided with true roots , stems , leaves and vascular bundles. Their seeds are exposed and remain in naked condition simply on the surface of the megasporophylls . The main points of differences between Gymnosperms and Pteridophytes are given below :

( 1 ) The majority of pteridophytes are homosporous whereas all gymnosperms are heterosporous .

( 2 ) The roots are adventitious in pteridophytes whereas in most of the gymnosperms , the roots are tap roots .

( 3 ) The stems are mostly underground rhizomes in most of the ferns , wheras in gymnosperms , the stems are aerial . 

( 4 ) The gymnospermous stems have a eustelic organisation whereas in the pteriodophytes , eustele is absent .

(5) The secondary growth is present in gymnosperms whereas it is absent in majority of pteridophytes .

(6) The gymnosperms produce seeds whereas pteridophytes do not produce seeds at all .

( 7 ) In all the living gymnosperms , the development of a pollen tube takes place from the pollen grains after their germination . Such a structure is absent in the heterosporous pteridophytes .

( 8 ) The female gametophyte is permanently retained within the megaspore , which is permanently retained within the nucellus of megasporangium .

( 9 ) In gymnosperms , the megasporangium is protected by an integument which is absent among the pteridophytes . This protected megasporangium is known as ovule and has a small opening or the micropyle at one end .

( 10 ) The archegonia among gymnosperms lack neck canal and neck canal cells whereas pteridophytes possess them . The archegonia are absent in Gnetum . 

( 11 ) Presence of a free nuclear division in the earlier stage of embryo development .