The purple blue flowers of topli karvi (Strobilanthes sessilis) blanketed the plateaus of Kaas and Chilkewadi in September and October of 2015 and 2016. A photo I had taken in the windmill-infested plateau of Chilkewadi last year shows the flowering bushes. Last year the weekend I spent in these high plateaus near Satara was rained out; we did not see the sun at all. This year the threatening skies remained dry, but the topli karvi was not in bloom. It blooms every eight years. The next blooming is expected in 2023. Botanists give the name “mast seeding” to synchronous flowering of many plants of the same species after intervals of several years. The Western Ghats have several species of Strobilanthes which do mast seeding.
You can see one of the round bushes of topli karvi in the foreground of the photo above. I looked closely at it. It was healthy, free of parasites and seemed to be vigorous. As far as I know, these bushes do not die after a flowering, unlike bamboo, which dies out after a mass flowering. Botanists would call the bamboo monocarpic, and the topli karvi polycarpic. Around these bushes you can see other flowers. This patch was full of flowering shoots of the common balsam (Impatiens balsamica). I’ve seen other flowering shoots poking out of the karvi bushes. But it is easy to pick them out. The topli karvi is a low round bush with dark green hairy leaves with serrated edges (see the featured photo for a closer look at the leaves).
I’ve never seen the fruit of the topli karvi, although I was told that it remains on the bush for most of a year. I’m not sure whether this information is correct. This behaviour is attributed to a different species of mast seeding Strobilanthes in a Wikipedia article: the hill karvi or the Strobilanthes callosus. I’d also seen the hill karvi flowering last year, and did not see it this year.
Two years ago The Family had taken the photo of flowers of topli karvi which you can see above. I saw a few scattered bushes in flower this year. The featured photo shows a flower bud developing. If you really want to see karvi flowers, it seems quite possible that you should be able to do this every year. It is mast flowering that you must wait for.
Why did Strobilanthes take to mast seeding, whereas other plants in the same plateaus flower each and every year? Some people say it is because of variable rainfall and heat; some years are just not conducive to flowering. Maybe so, but then other nearby plants flower every year. Some say that these plants could be responding to the weather quickly by flowering, but then the eight-year cycle would not hold, because the monsoon does not have such a predictable cycle. A third set of people say that the karvi has this long cycle because it is synchronized to the long cycle of a pollinator. I haven’t seen a study of the pollinators of the karvi, and in any case this just shifts the problem on to another species. Why would the pollinating species have a long cycle? Since I have not seen the fruit of karvi, I do not know whether this has such large seeds that it is inefficient for the plant to seed every year. Could it be, as some believe, that synchronized seeding serves to produce such a large amount of fruit or seed that animals which eat these cannot possibly eat all the fruits or seeds produced in a mast seeding year? I guess someone has to study the animals which feed on karvi to find out.
Although the topli karvi grows widely, it is a mysterious plant. This is a mystery which I will not be able to solve. The solution will come from a younger person who can see it go through several cycles of bloom and fruit.