The call of the Hornbill

Yesterday I heard the call of the hornbill again. In the last few years a pair has nested in one of the tall trees in the garden. The nesting season is before March, and the birds are gone by April. The featured photo was taken in early March this year. Mid-October seemed a little too early for these birds to nest.

I was discussing this with The Family when she floored me with a bit of nature lore. Apparently hornbills prey on small birds, and have been spotted raiding the chicks of rose-ringed parakeets. Our garden is full of flocks of these raucous bright green pests. The parakeets nest from September to December. So this is a time when the first chicks have hatched. Maybe these Hornbills were here early to hunt. If so, we should thank them for keeping the population of the parakeet pests in check.

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Butterflies before breakfast

I was trying to trace a persistent error message in my camera and eventually found that it was due to a lost set of photos taken two years ago. I’d taken them during an early morning walk to look for birds inside Nameri national park, on the border between Assam and Arunachal Pradesh. On the way back we saw a large number of butterflies in a space of about 15 minutes. I managed to photograph a few of them. This is what biodiversity means!

Flowers of the Sahyadris

Kaas plateau is a seven hour drive from Mumbai. The herbs flower in the closing weeks of the monsoon: between September and early October. Many of the flowers you see here are also found in the nearby Mahabaleshwar plateau and in Lonavala, closer to Mumbai. Expect lots of small herbs, few bushes and trees only rarely. Be prepared for long walks in rain and mud, with no food and water except what you carry with you.

Flowers and herbs of the Western Ghats, especially of the Sahyadris, are now well documented. There are many guides for amateur naturalists like me. I was introduced to the pleasures of flowers by Adesh Shivkar and Mandar Khadilkar; google them if you wish. There is nothing available yet for an amateur explorer of the fascinating tiny world of mosses and lichens (see the featured photo).

Purple bladderwort

The bladderwort (called Utricularia by botanists) is the biggest family of carnivorous plants. In the Kaas plateau we saw large fields of purple bladderwort. The plant is aquatic: it floats on the thin film of water trapped above the stone of the plateau. The long stalks of the plants grow leaves at intervals. The bladders, which give the family its name, grow along the leaves and usually stay below the surface of water. Bladderworts are widely known to be carnivorous plants. Their bladders trap tiny invertebrates. I later found that this two hundred year old picture of carnivory may be wrong.

Plants turn to carnivory when the soil is poor in nutrients. However, they do not give up photosynthesis; their leaves are still green with chlorophyll. Carnivory gives the plant nutrients like phosphorus and nitrogen which are in short supply in the soil. The first blow to the idea of purple bladderwort being carnivorous came from careful measurements of the animals found in the bladders. These showed that at most 1% of the nitrogen and phosphorus that the plants need can come from the animals.

Purple bladderwort

Yet more amazing is that each of the bladders seemed to contain a whole live ecosystem of the small invertebrates which were trapped. New bladders did not have them, and older bladders had more animals. So it seems that the purple bladderwort is not a carnivore. It must gain something else by sustaining this ecosystem inside itself. Unfortunately no one knows yet what the plant gains from this. But it seems that the purple bladderwort (named for the purple flowers you see in these photos) may not be a carnivore.

The Karvi does not bloom any more

The purple blue flowers of topli karvi (Strobilanthes sessilis) blanketed the plateaus of Kaas and Chilkewadi in September and October of 2015 and 2016.Windmills in the middle of fields 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.

Topli karvi bushes in Chilkewadi

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.

Topli karvi flowering in 2015

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.

Sundews

The carnivorous sundew which you see in the featured photo is properly called the Drosera burmanii or Burman’s sundew. It is mistakenly called Burmese sundew sometimes. The story behind the name took me back to the origins of modern biology. It was described in detail in a book by the Dutch physician Johannes Burman, who spent a few years in Sri Lanka. His assistant in the production of this book, called Thesaurus Zeylanicus, was Carl Linnaeus. This was 1735, and Linnaeus had just published his own book, the Systema Naturae, which was to change the world by inventing a new way of naming all living creatures. Linnaeus’ naming system is the one all biologists and amateur naturalists follow. Darwin, in his book Insectivoruous Plants, remarked on the common trapping mechanism through the sticky “dew” which you can see in the photo, and classified all sundews into one family, which is still called the Droceraceae.

Darwin was a wonderful naturalist and asked most of the questions which keep drocerologists busy till today. Are the sundews selective about their prey? In the nearly three centuries that have passed since the first descriptions of sundews, all evidence indicates that they are generalized carnivores. They feed on whatever gets stuck in their dewy glue. How large can their prey be? Darwin believed that they feed on fairly small animals. Strangely, there have been no measurements of their prey since 1925; and that was the first one since Darwin himself.Drosera burmanii So, if you happen to take photos of any sundew with its prey, you will add substantially to the sum total of human knowledge. I scanned about 20 plants quickly, and if they had captured prey, then they were too small for me to see with my unaided eye (the photo here shows a small insect stuck to the plant). Are all carnivorous plants related? Fossils and genetic data seem to say that carnivorous plants evolved six times independently from completely different origins; so the bladderworts and sundews that I saw were not related.

A question that Darwin never asked is why a plant would turn from photosynthesis to carnivory. The general observation that these plants grow in nutrient-poor soil was taken as enough of an answer. However, there are other entirely photosynthetic plants which grow all around the sundew, so this is not a complete answer. Studies show that carnivorous plants grow and spread better once they get enough prey. Notice the bits of green on the leaves of the D. burmanii? These contain the usual chlorophyll that allow plants to use sunlight to make sugar. The density of spiny hairs is much smaller on this portion than in the red part of the leaves. So they also do photosynthesis, but they are less efficient at it. The complete story of carnivory versus photosynthesis is not yet known.

Drosera indica flowering

In the same patch of ground where I took the other photos, I also saw several flowering specimens of Drosera indica (one example in the photo above). This was first named by Linnaeus in 1753 based on a drawing of a plant collected in Sri Lanka. A field study in 2013 by Allen Lawrie found that there are actually 11 different species which were conflated into the single species D. indica. Are there several unrecognized species hiding behind this one label in India? I do not know the answer.

While we talk about names, you will notice that I have called these plants carnivorous instead of following Darwin and calling them insectivorous. This is because detailed counts of prey species indicate that sundews feed on anything the right size, without specializing in insects. I’ll not say much more about D. indica because I’ve already written about it in another post.

Are D. burmanii and D. indica in competition when they grow in the same patch of ground? Studies of prey captured by other carnivorous plants which grow together show that they capture the same species, and so may be considered as competing. I know of no studies of prey species among the sundews of the Sahyadris, but there is no reason to believe that they are exceptions. In that case the spreading stalks of the indica with their larger numbers of leaves possibly give it a photosynthetic edge. Maybe that is why they are more common. I wish I knew a professional ecologist who could answer these questions.

Dipcadi

“What’s that flower?” The Family asked me as I was stalking a Ceropegia. I looked around at the pentagonal white shapes on a stalk that was about 20 centimeters high. “I don’t know”, I said, as I took a photo for later reference. She soon found that it was not a flower. A flower has sexual organs, and this did not have any. Mandar explained that it was the opened fruit of the Dipcadi montanum. I’d posted about this plant from the Hyacinth family last year after a single sighting.

Dipcadi montanum fruit and flower

This year I’d seen it several times. In fact just a few minutes before I’d seen another stalk which had started fruiting. You can see the fruit towards of the bottom of the stalk in the photo here: a dark green knob. The chance sighting I had last year was of the D. montanum plant standing in a field of bladderwort (Utricularia). Each sighting this year showed the same thing. In fact, the purple spots which you see in the featured photo are purple bladderwort. The linkage between the two just got stronger in my mind because of this statistical improvement. Typically the bladderwort grows in poor soil, and gets nourishment from digesting small insects. There is evidence of a rich ecosystem which grows inside the bladder. Does this ecosystem produce benefits to the thin soil around it which are reaped by the bulbs of the Dipcadi? I don’t see anything written about it.

Dipcadi montanum

I got a sharp photo (above) of a flowering Dipcadi on the nearby lateritic plateau of Chilkewadi. The spots of white that you see in the photo are of globular pipewort (Eriocaulon sedgewickii). These are known to grow in association with bladderwort. In fact the field had some, although they do not appear in the photo. The triple association of Dipcadi, bladderwort and pipewort is very strong, and cries out for an explanation.

The rarest flower

The genus of plants called Ceropegia are pollinated in a very strange way, The Family explained to me. After her first trip to Kaas plateau two years ago, she showed me photos of this strange flower and explained how they trap flies to pollinate themselves. The upright flower opens up and flies come in to look for nectar. As soon as they land, the petals close into the cage shape you see in the featured photo. The frantic fly buzzes about and pollinates the flower. After this the flower droops down and opens up to let the insect out. In the bunch of Ceropegia vincaefolia that you see in the featured photo, two of the flowers are ready, and the droopy one has been pollinated already. These tall bushes were fairly common around the Kaas lake. Apart from the mode of pollination, I found the green colour of the petals rather unusual.

Ceropegia jainii

But the most marvelous sight of the trip was this tiny plant on the plateau: Ceropegia jainii. I was lucky to be with two naturalists who knew roughly where to look. This species is a little rarer than tigers. In the photo you see the green egg-shaped base called the crown kettle, and the purple crown tube formed by the five petals. If you look closely, you will see the downward pointing hairs inside the tube which trap the fly. If this flower is similar to that of the C. vincaefolia, then at the narrow bottom of the crown kettle is the hard-to-reach corolla. I was not going to dissect such a rare flower to look inside it. The whole flower is a little less than two centimeters long. You can see that it grows on an unbranched stalk with thick leaves. In the photo above you can see other buds forming on the stalk.

I was so thrilled with the sight that I noticed the caterpillar only after looking at the photo. It will eventually grow into the spectacularly coloured butterfly called the plain tiger (Danaus chrysippus). I don’t know whether there is an association between this and C. jainii. Since host plants of the plain tiger include other known milkweeds (family Asclepiadoideae) it is not impossible. On the other hand, I did not see the typical circular holes that the caterpillar makes in the leaves of its host plant. In any case, this is something to watch for in future.

The commonest flower

Sonkadi (Pentanema indicum) is a short spreading herb which you see almost everywhere in India when it is not too dry. In the monsoon it grows all over the Sahyadris. Clusters of these yellow flowers can be found in roadside ditches, wastelands, as weeds in untended gardens. It is often used in folk-medicine, to cure everything from colds and fevers to stomach pains. In fact so many useful chemicals have been extracted from it that there are studies on how to grow the flowers in the lab without having to grow the whole plant.

Pentanema indicum, sonkadi

Why is it so hardy and widespread? Where did it come from? After a lot of search I found that these simple questions are too complicated to answer now. It turns out that this species is a member of the largest family of flowering plants known. This is the sunflower family, called Asteraceae. Within this family is a tribe called the Inuleae whose core members have yellow hermaphroditic flowers. This is where the Sonkadi belongs. This is a partial answer to the questions that arise in my mind whenever I see these hardy plants poking out of inhospitable spots.

Plateau of flowers

I’ve written about the world heritage Kaas plateau before. I went back there over the weekend. The volcanic rock barely holds any soil, and what little is there has little nutrient. The plants that one can see here have evolved in this hard environment. As a result, this 10 square kilometer area at an altitude of about 1.2 kilometers is an island mountain: the flora here is isolated from flora in other plateaus in the region. There’s a brief but glorious flowering at the end of the monsoon. By all accounts the flowers change almost every week.

Kaas plateau: landscape

The most famous plant here is the Topli Karvi (Strobilanthes sessilis) which blooms in mass once every seven years. Last year this was in bloom. This year the general view (see photo above) did not show any of the bright blue flowers of this bush. One had to search hard for the few isolated and idiosyncratic bushes of S. sessilis which flowered this year. Instead the landscape was full of patches of white globular pipewort (Eriocaulon sedgewickii) mixed in with the vivid colours of the carnivorous purple bladderwort (Utricularia purpurascens). In other places we patches of the yellow sonkadi (Pentanema indicum) mixed in with the violet rosemary balsam (Impatients oppositifolia). You can see all four species in the featured photo.

This week the balsam outnumbered everything. Most green patches had highlights of violet. Maybe by next week the sonkadi will dominate.