One of the most recognizable of the many species in the genus Niloo sensu Janzen (Strobilanthes) is sadly missing from the handbook Flowers of Sahyadri. This is the species called Strobilanthes sessilis. They most easily recognizable as small bushes which look like an inverted basket (see photo below). This gives them the popular Marathi name of Topli Karvi (topli is the word for basket in Marathi). It is rather widespread, and recognizable also by the deeply grooved elliptical leaves, serrated at the edges and hairy. Even the stalks and buds are hairy, and the flower is the blue which gives Niloo its generic name. It is widespread enough and easy to recognize, and should be in handbooks.
I’d first seen it a few years ago on a trip to the Kaas inselberg. I was new to the flowers of the region, a tyro wildflower spotter, but it didn’t take me any time to learn to spot this plant. Over a couple of years I saw it flowering in late-September and October. This year I saw it in the region of Lonavala, flowering in mid-August. This agrees with the report of flowering times that I saw in eFloraIndia but disagrees entirely with the timings given in Indiabiodiversity and FlowersofIndia. The bushes are reported to be found in the northern end of the western ghats, a much more restricted range than given in the Kew plant list. The limited geographical range is not surprising, since other species of Niloo are reported also to be similarly rare.
One more thing that puzzled me are scattered reports of mass flowering at variously long intervals (called mast seeding). Not impossible at first sight, since about 50 species of the approximately 350 in the genus mass flower after many years. For example, eFloraIndia claims that there is mast seeding of S. sessilis every 9-13 years. There is a variant report in 2008 of its mast seeding in two successive years in Kaas. I saw it mast seeding in 2015 and 2016 in Chiklewadi and Kaas (the featured photo is from 2016). What I saw this year in Lonavala was not mast seeding. Puzzled, I looked at reports on the mast seeding of bamboo and Niloo.
It turns out that mast seeding may be an emergent property of populations and not determined genetically. An article by Janzen documented reports such historical reports for both bamboo and Niloo, and gave detailed observations which could support such a hypothesis. I found this article to be a wonderful read, as clearly written as the classic of natural history by Gilbert White. Another article reports genotyping of a different species of Niloo which mast seeds in one of three different locations. The close similarity of the three genomes led them to believe that the differences in flowering habit had to be sought at the population level instead of individual. Nevertheless, individuals from a mast seeding population continue to flower after many years even when propagated to a different location. What triggers mast seeding in individuals of one population but not in another? Unfortunately the answer is not yet known.