As promised, here is the second part of my garden expedition at my sister’s place, in which I explored the leaf surfaces of dicot plants. I selected four plants to observe stomata: tomato (Solanum lycopersicum), coatbuttons (Tridax procumbens), spinach (Spinacia oleracea) and chilli peppers (Capsicum annuum).
Here is a comparative figure for the upper and lower epidermis of the four dicot plants, which I observed through the foldscope.
In dicots, it is known that stomata are distributed irregularly in the lower epidermis and the guard cells are bean shaped. I too found that the guard cells were bean shaped, but I found the stomata of tomato and chilli leaves distributed all over the upper and lower epidermis. Further, I saw trichomes on both upper and lower epidermis of tomato and chilli leaves. It puzzled me, whether again these were exceptional cases or not!
At this point, I stopped my observations and started checking my findings by searching on the internet. I learnt that dicot plants do have stomata on the upper epidermis and, in order to control transpiration, trichomes are produced (on both upper and lower epidermis) to cover up the stomatal openings. This is very clear in tomato and chilli which both belong to the same family.
In Tridax too trichomes are produced. Looking at the lower epidermis image for Tridax, you see a few cases of one small cell in the middle and what looks like two big cells surrounding it. Initially, I considered these to be stomata. However, after some literature search, I concluded that these cells actually form the base of a trichome.
I enjoyed this vacation research with my foldscope. I welcome your suggestions and comments!
In the 3rd and final post for this short project, I will provide a comparative view of the monocots and dicots together.
(with Debashree and Jayashree)