Cities and Canopies

by Harini Nagendra

  Birds are not the only creatures that make trees their home. Insects, both tiny and large, can also be found on city trees. Some are almost invisible to the naked eye. The rain tree is a common avenue tree in many cities such as Chennai and Bengaluru, with leaves that droop and face sideways (owing to the presence of a pulvinus, or a thickening of the base that enables the leaf to move like a hinge) during the night or on a cloudy day. This has given it the name thoongumoonji maram (sleepy-face tree) in Tamil. Sunlight causes the leaves to open up, creating a dense canopy that casts a cooling shade. Some say that the name ‘rain tree’ comes from the droplets of nectar dropped by sap-sucking insects on the tree in its native habitat.

  Flowering trees on avenues are like buffets laid out for a variety of creatures. The African tulip, a common avenue tree, is usually abuzz with activity. The deep red flowers of the African tulip store a small pool of nectar that attracts many insects. The walls of the flowers are sticky, preventing them from getting out. These pools of nectar can therefore prove to be deadly for ants, bees and butterflies who drown in them while trying to access the nectar. Their unfortunate corpses can sometimes be found floating in the nectar. Other insects such as the praying mantis, meanwhile, patiently wait in the African tulip’s foliage for prey.

  Butterflies of all kinds inhabit our cities. Butterfly walks are held in many cities such as Pune, Bengaluru and New Delhi, and attract crowds of enthusiasts. Many urban naturalist groups have developed small, innovative and colourful field guides to butterflies and birds to attract children and novices to nature in the city. Skinks move swiftly around tree patches, attracting us with a flash of colour as they chase unwary butterflies and other insects. Stick insects, leaf insects and chameleons confuse us with their ability to blend into the background, going unnoticed till they move. Tree frogs with their green or bark-like bodies cling to the bark of trees or green shoots, while snakes of all kinds slither swiftly up and around the bark of trees, sometimes dropping down on the heads of unwary passers-by. If you have had this experience, you will certainly never forget it all your life.

  Ants, tiny though they are, constitute nearly 25 per cent of the total animal weight in the tropics. They have also proved to be very versatile, adapting to living in a range of habitats in cities. The weaver ant is a common species of arboreal ant that nests on many types of trees. These ants prepare their nest by carefully weaving together the leaves, coaxing ant larvae to release silk. These nests can be seen on trees in parks if we keep an eye out for leaves that appear to be stuck together. If we are lucky, we can find these built at eye level, allowing us to examine the busy goings-on as ants enter and exit the nest. We may even get to see the nest being built, a fascinating example of cooperation and hard work. But remember to keep a safe distance, the bite from these ants is very painful.

  In 1997, researchers discovered a new arboreal ant in Bengaluru. The ant, a spineless two-node variety, was identified as a new species and named Dilobocondyla bangalorica in 2007, after the city where it was discovered. This is the first species of this genus to be found in India. This ant prefers to make its nests in the cavities of plumeria and acacia trees. Plumerias are native to the Meso-American and Caribbean region. The gouty-looking plumeria is planted in Hindu and Buddhist temples, as well as in Hindu and Muslim burial grounds. It is fascinating that a tree from such distant lands has not only become culturally important, but also provides a habitat for an ant species found only in India. Trees of different species also host terrestrial ants that clamber up trees to forage for food and use leaf litter on the base of trees in parks and gardens, and fallen branches as nesting sites. Our first instinct on seeing an ant may be to squish it to avoid being bitten. But if we are patient and tolerant, ant watching like birdwatching can reveal

  a whole new world to us. Like the new species of ant discovered in Bengaluru, perhaps there are more species waiting to be discovered in cities.

  The presence or absence of ants and other critters like tree spiders also tells us about the state of our urban greenery. Ants are extremely adaptable. In disturbed urban areas, the number of species and the number of ants are often higher than in protected sites. However, more common species are found in the disturbed sites while rare species persist in undisturbed areas. Ants act as ecological indicators, telling us about the health of an ecosystem. In urban sacred groves in towns in Kerala, the abundance of the yellow crazy ant, which nests in leaf litter at the base of trees, is indicative of the pressures of urbanization. This ant is an invasive species and its presence indicates a disturbed habitat.

  One of the most common mammals we see in cities are squirrels. These striped rodents clamber about branches, chasing each other and snacking on the fruit pods of the African tulip. Bonnet macaques seem to like the succulent buds of the African tulip too, as well as the flowers of the gulmohar. Fruit bats flit about, feasting on fruits of the cluster fig and the Indian mast tree, leaving behind scattered seeds as evidence of their night-time banquets. Some rare species can also be found in the tree canopies of cities. The slender loris is an endangered nocturnal primate that lives in the canopy of trees. At night, this shy primate forages for fruits and insects on treetops and rests in hollows or under leaf cover in the daytime. Though close cousins of the monkey, the slender loris cannot jump from one tree to another and must crawl along the branches. Consequently, it needs a continuous and connected canopy to move from one tree to another.

  Young lorises stay in clumps of vegetation created by creepers and vines on trees while the mother loris goes foraging. The slender loris is a species that hardly ever comes to the ground, depending entirely on tree cover to survive. It has been spotted in the heart of busy Bengaluru where there is still continuous tree cover in parks, educational and research institutions. But the cutting of trees and fragmentation of habitats is a major concern for this endangered species. Its survival will depend on how successful we all are in ensuring that the green cover of the city is protected.

  All trees in the city, whether on streets, in parks, homes, lakesides or commercial areas, harbour a variety of animal, bird and insect life. From tall coconut palms to spreading rain trees, from exotics such as the sausage tree to the native mango, from the fruiting jackfruit to the flowering African tulip—all trees are home to a variety of biodiversity. Plantation schemes in cities should avoid focusing on single species, whether native or exotic. Instead, a khichri of trees would perhaps support a healthier diversity of fauna.

  Above all, trees bring us close to our non-human neighbours. Biophilia, defined by the naturalist E.O. Wilson as ‘the innate tendency to focus on life and lifelike processes’, is a part of our human identity. It is a love of life that extends beyond caring for humans and embraces all life—animal, bird and insect. Spending more time carefully observing our trees is a good way of reviving the dormant biophilia in each one of us. For school- and college-going students with access to a wooded campus, there is no better way of starting to engage in this process than by looking up at the trees around and observing the animal, bird and insect life that the trees reveal. A love for nature encouraged from a young age can mean a lifetime of caring for our planet.

  FOUR

  THE SHAGGY-

  HEADED

  BANYAN TREE

  The banyan, the national tree of India, is unforgettable once you see it. With thick aerial roots that grow down from the branches and penetrate the ground, the tree looks like it has many trunks, all collectively holding up its branches with leaves. The banyan has a long and ancient history in India. Alexander the Great, the Greek king who invaded north-west India in the third century BC, is believed to have been struck by the sight of this impressive tree. He sent the news of the banyan tree to his teacher, the famed philosopher Aristotle.

  Aristotle’s successor and pupil, Theophrastus, also called the Father of Botany, was equally struck by the news of this massive tree. Theophrastus described the banyan in two of the oldest books on plants, On t
he Causes of Plants and the Enquiry into Plants, written between the third and second centuries BC. A few centuries later, Roman naturalist Pliny wrote about the tree as being so large that within its branches ‘whole troops of horsemen may be concealed’. The tree had captured the romantic imagination of the Europeans.

  Spreading like wildfire across Europe, the tale of the charismatic banyan eventually made its way into English poet John Milton’s famous poem Paradise Lost. In the poem, published in 1667, Adam and Eve made their way:

  Into the thickest Wood, there soon they chose

  The Figtree, not that kind for Fruit renown’d,

  But such as at this day to Indians known

  In Malabar or Decan spreds her Armes

  Braunching so broad and long, that in the ground

  The bended Twigs take root, and Daughters grow

  About the Mother Tree, a Pillard shade

  High overarch’t, and echoing Walks between;

  There oft the Indian Herdsman shunning heate

  Shelters in coole, and tends his pasturing Herds

  At Loopholes cut through thickest shade: Those Leaves

  They gatherd, broad as Amazonian Targe,

  And with what skill they had, together sowd,

  To gird thir waste, vain Covering if to hide

  Thir guilt and dreaded shame.

  The Europeans were struck by how large the leaves and branches of the banyan tree were and, in comparison, how small the fruit. But these tiny fruits contain a world of mystery within their folds. Sometimes called the world’s strangest fruits, the fruits of all ficus trees, commonly called figs, are actually inflorescences (the technical term for these is ‘syconia’—an obscure piece of botanical trivia that may come in handy for avid quizzers). Within the fruit are the flowers. If you stop to think, it is strange that the banyan—or indeed the peepul, or any other ficus tree—never seems to bear flowers. In fact, the fruit itself contains a large number of tiny flowers packed tightly inside. These are essential for the pollination of the tree, which is done entirely by wasps.

  Vegetarians who eat figs, beware. Many fig fruits are stuffed full of dead wasps. When the fruit is unripe and green, it looks unappetizing to humans but sends out enticing smells that attract a specific kind of wasp—agaonid wasps whose lives are tightly intertwined with that of the fig. Pregnant female wasps, their stomachs bulging with eggs, enter through a small hole at the tip of the fruit. Since the hole is very small, they have to squeeze their bodies through it. It is such a tight fit that their wings and antennae fall off. The unfortunate wasps ultimately die within the fig.

  As the fig ripens, the wasp eggs hatch inside the body of the mother, beginning a new cycle of life. The young male and female wasps mate inside the fig. The newly pregnant female wasps then make their way out of a ripe fig and look for an unripe fig to continue the cycle. As they enter another fig, they carry the pollen from the original host on their bodies, pollinating the new host and continuing the process of seed making.

  The cycle of the wasp and the fig, both dependent on each other, leads to an unusual outcome. Most trees fruit only at specific times of the year, but not the banyan and other ficus trees. Because the wasps feed only on the figs, and since the wasps are short-lived, the tree needs to continuously produce fruit—so that the wasps always have a source of food available. This prodigious capacity of the ficus trees to produce fruit throughout the year is exploited by many other animals, birds and insects. Giant hornbills, tiny ants, civets, bats, monkeys and slender lorises—all feast on the ficus. In Indian cities, it is common to see a raised platform with a giant banyan tree where people sit comfortably in the shade and enjoy a long chat, a game of cards or chess. The canopy is an equally bustling hive of activity, with chattering birds, monkeys and insects of all shapes and sizes gorging on the fruit. Small wonder that many Indians believe this to be the kalpavriksha or kalpataru, the wish-fulfilling tree considered sacred in Buddhism, Jainism and Hinduism.

  Long before the Vedic texts that describe the kalpavriksha, the Indus Valley civilization may have known the tree. One of their symbols, a stylized three-branched fig tree with lines on each side of the stem, is interpreted by some experts as representing the banyan, with the lines indicating the aerial roots. The proto-Dravidian word for the banyan is vata maram (roe tree), as it is still called in Tamil. In Sanskrit, the tree acquires a related name, vata vriksha. In Kannada it is the ala mara, in Marathi the vad, and in Hindi the bargad—all related names. Where then did the word ‘banyan’ come from? The name seems to have been the result of a confusion created by the Portuguese, who noticed banias (traders) often sitting below the tree. They conflated the name of the community with that of the tree. That name passed down from the Portuguese to the British colonials and entered the English language.

  It is not only the Indians who venerate the tree. The Indonesian flag has the banyan tree—its branching roots are believed to represent the many islands that make up the country. The banyan is revered as a symbol of unity, bringing together many different islands with their own cultures, languages and historical roots into a united whole, which is a beautiful concept.

  Growing to giant proportions, banyan trees are easy to identify because of their unique aerial roots. These roots arise from the branches of the tree and grow towards the earth. At the ends of the

  roots are feathery tendrils—making the end look rather like

  the tail of a cow or the tangled end of an uncombed plait. After the root touches the ground, it enters the earth, tethering the tree.

  The root then begins to thicken and widen into a thick woody trunk. Over time, a single tree can spread horizontally over a vast area covering several acres, looking like it is composed of multiple trunks and branches. In reality, the entire tree is one giant entity whose weight is supported by multiple aerial roots that act similar to the supporting beams or columns we use to build our houses. With old trees, it is sometimes impossible to tell which trunk is the parent and which are the clonal offspring that began their lives as roots. A tip passed on by one of our grandmothers is to add banyan roots to hair oil for better hair growth. If you do, she said, your hair will never stop growing, just like the roots of the banyan tree.

  Interestingly enough, the banyan is also a favourite of bonsai specialists who find its root system very amenable to pruning. As the aerial roots grow and thicken, they are bent into preferred shapes using wires and other supports. The Kaiyuan monastery in the coastal Taiwanese city of Tainan has a banyan bonsai that is over 250 years old.

  Sacred to Hindus and Buddhists, and revered and protected across Indian cities, the banyan is also a tree of paradox. A life-giving keystone species that supports diverse species, the tree also acts as a strangler fig, an epiphyte that grows on and surrounds its host tree, often killing it.

  Despite being one of the largest trees in the world, the banyan can also begin life as an epiphyte, in tiny spaces of refuge on other trees. Fruit-eating birds eat the banyan fruits or figs. When they excrete, the birds drop the seeds into a crevice of another tree, or a fork between two branches. The banyan sprouts in such seemingly unfavourable contexts, exploiting any rotting leaves or other material that may have fallen in this crack or crevice to support its early growth.

  The seed begins life as a commensal, tagging along on the main host tree. But as the seedling grows into a young tree, its aerial roots begin to surround the host, ‘strangling it’ as they dig their way greedily into the soil. The leaves form a thick canopy that grows over the host tree, thus robbing it of light from above and sustenance from below. Starved of food and squeezed from all sides, the host tree eventually dies, leaving the banyan—called a strangler fig for obvious reasons—thriving. Other ficus species such as the peepul can also become strangler figs, but the banyan is one of the most common species that does this. This is an evolutionary trick that enables fig trees to grow tall and grab the light from the host, as light is necessary for tree survival, b
ut very difficult to get in tropical forests where these trees evolved.

  It is not just other trees that the banyans have taken over. In humid coastal places like Goa, and in cities such as Mumbai and Kolkata, it is common to see banyan trees (and their close cousins, the peepul) sprouting in the crevices of old houses. Left unchecked, these trees eventually take over the house, flourishing exuberantly in decaying urban heritage homes and giving majestic old bungalows an exotic look of a bhoot bungalow (haunted house), most popular in Indian movies where ghosts play a central role. Add to this the poignant fact that many Indian freedom fighters were executed by public hanging under banyan trees and it is clear why this majestic tree, which has witnessed events both heroic and tragic, is India’s national tree.

  The banyan is a favourite of poets and prophets, storytellers and myth-makers worldwide. Some say the tree that Alexander saw is the same as Kabir’s banyan. According to local legends, this massive tree grew from the toothbrush of the fifteenth-century mystic poet Kabir, which he tossed aside after use. Kabir’s banyan on Kabirwad Island in Bharuch, in the middle of the Narmada river, is said to have once covered an area close to 17,000 square metres and was so large that it could shelter 10,000 horses. If it is indeed Alexander’s tree, as it seems likely from the location described by his companions, it is far older than Kabir. The truth of its origins is lost in the shifting sands of history. But we know more about the history of some other famous banyans.