SIGNIFICANCE OF LIGHT WINDOWS IN FLORAL BIOLOGY OF SOME ANGIOSPERMS

Konrad sprengel (1793) realized the importance of various types of spots on the floral parts of angiosperms. He assigned the term "nectar guide" to these spots and correlated them with the phenomenon of pollination. In addition, to the nectar guides, certain angiosperms like Aristolochiads, Asclepiads, Orchids, Sterculiads and Zingibers also exhibit translucent areas, of various size and shapes, near the hidden reproductive organs and nectar source i.e. the nectary. Among sapromyophilous blossoms of Abroma, Aristolochia and Ceropegia, the light coming out of the translucent areas leads the insect visitors towards their reproductive organs. However, among meliferous blossoms of Orchids and Zingibers, the light coming out of the translucent areas leads insect visitors towards the nectar source or nectary. These translucent areas have been termed as "Light windows" by Mc Cann (1943) in certain members of family Asclepiadaceae and Araceae. However, Chaturvedi (1993) has further reported the presence of translucent areas on outer corona lobes of some Indian species of genus Ceropegia and assigned them for attracting the pollinaria loaded insects for successful pollination. The present paper deals with the morphological studies of light windows among certain Asclepiads, Orchids, Sterculiads and Zingibers and correlates their role in the process of pollination by insect visitors.