why are most or should i say all anthers bilobed and dithecous ? what kind of importance this kind of structure offer ? is it to promote more number of pollen grains,better dehiscence technique or some other reasons ?
An anther is bilobed and dithecous means each anther has two lobes and each lobe again has two chambers. Each chamber bears a single microsporangium. So there are four microsporangia in each anther. If the anthers are not lobed, they can only accommodate one sporangium. To produce more number of pollens by each anther, it is bilobed and dithecous.
Well, nature hardly obeys such reasons. All we can do is to explain with our little knowledge what we want to understand. It may be to provide better nutrition to pollens. You can also visit a blog called neetpcb.blogspot.com and post your question there. Though its a new blog, the experts are really good and its a good initiative.