Select one of the following pairs of important features distinguishing Gnetum form Cycas and pinus and showing affinities with angiosperms
Select one of the following pairs of important features distinguishing Gnetum form Cycas and pinus and showing affinities with angiosperms
(a) absence of resin duct and leaf venation
(b) presence of vessel elements and absence of archegonia
(c) perianth and two integuments
(d) embryo development and apical meristem
1 Answers
Correct option (b) presence of vessel elements and absence of archegonia
Explanation:
The presence of vessels in the xylem is an angiosperm character found in Gnetum which distinguish it from Cycas and Pinus.
Gnetum resembles angiosperms in many other aspects also like
(i) The leaves in Gnetum have reticulate venation that is an angiospermic character.
(ii) In General female gametophyte is only partly cellular before fertilisation and becomes completely cellular only after fertilisation. Some of the free nuclei act as eggs as there are no archegonia.
The short apices in Gnetum and angiosperms show a distinct tunica and corpus configuration.
The cortex of stem of Hanus is traverse by Large resin ducts or canals. Each duct or canal is lined by a layer of thin walled parenchymatous glandular secretory cells constituting epithelium. The epithelial cells secrete resin into a canal. The resin is the chief source of turpentine.