Cities and Canopies

by Harini Nagendra

  In the 1900s, amaltas trees were found in many parts of Bombay (now Mumbai). The south Mumbai neighbourhood of Byculla is said to have derived its name from bhaya-kala (the level ground of the bhaya/bawa, which is the amaltas). The British called it the Indian laburnum. Interestingly, Laburnum Road in south Mumbai also derives its name from the row of amaltas planted during the British times. These trees have now disappeared from the road—having been replaced by Peltophorum trees with yellow flowers, but these cannot match the singular glory of the amaltas. Similarly, there was said to have been a beautiful amaltas in the compound of Hotel Spencer in Chennai with a girth of seven feet.

  The tree is not just beautiful but also useful. It is known as the aragvadha (disease killer) in Ayurveda for its medicinal properties. The pulp that separates the seeds is sweetish and used as a purgative and laxative (a bizarre factoid that does not gel with the gentle beauty of this gorgeous tree). A paste of the root helps with skin diseases and the leaves can help heal ulcers. The colourful flowers can be used as a vegetable dye for fabrics like wool, while the dried and powdered flowers are a natural colour used in Holi. The wood is hard, used for firewood, agricultural tools and fence posts. The bark produces a red dye that is used in tanning. Because of this property, amaltas was much in demand in British India. In Bengaluru, a letter dated 23 June 1873 describes a request from one Badódm´ Sábi for ten cartloads of the bark of the amaltas, to be used for tanning, at a rate of Rs 2 per cartload.

  But not all people are enamoured by the tree. It is considered to be invasive in Queensland, Australia. Closer home, there is a belief among the Gonds that bringing a part of the tree into the house can cause family discord. The Gonds place the seeds of the amaltas in the thatched roof of their enemies’ houses. As the seeds in the dried pod rattle in the wind, the residents of the house are believed to become noisy and quarrelsome.

  The blossoms of the amaltas have caught the imagination of many poets and writers as well. Ida Colthurst wrote a book on the flowering trees of India in 1926, describing the blossoms of amaltas as ‘graceful, tossing plumes of glowing gold’. Sarojini Naidu, freedom fighter and poet, was also enamoured by the blossoms. Her poem ‘Golden Cassia’ says:

  O brilliant blossoms that strew my way,

  You are only woodland flowers they say.

  But, I sometimes think that perchance you are,

  Fragments of some new-fallen star;

  Or golden lamps for a fairy shrine.

  Or golden pitchers for fairy wine.

  No one can remain untouched by the beauty of these golden chandeliers. The spectacular blossoms of the amaltas ensure that the tree finds a special place in any book on flowering trees in India.

  Amaltas (Cassia fistula)

  Description: Medium-sized to small tree with low branches. Smooth yellowish bark that darkens with age and is covered with crusts.

  Flowers: Bright yellow, in drooping bunches; older flowers at base and younger ones towards tip.

  Fruits: Long cylindrical pipe-like pods, black when mature, very tough to open and enclose seeds in compartments separated by sticky pulp.

  Leaves: Leaves shaped like imli (tamarind)—but larger.

  Seasonality: Deciduous tree that sheds leaves starting in March and extending into May. The beautiful bright flowers appear in late April and flowering can extend into July or even later. Fruits usually ripen between December and April.

  Family: Fabaceae. Seeds in this family look like beans.

  Origin and distribution: Native to India and found across the dry and moist deciduous forests of the country.

  THIRTEEN

  NATIVE AND EXOTIC:

  IDENTITY CRISES

  OF TREES

  For as long as people have lived on this planet, there have been questions of belonging and identity. Reams of newsprint and hours of passionate debate have been devoted to questions of who is ‘originally’ from a place, and who is an outsider. Perhaps surprisingly, the same debates also rage about the identity of trees. A variety of terms are thrown around—native, exotic, naturalized, invasive. Alien invasive species are ranked alongside deforestation and climate change as one of the biggest threats to biodiversity that the world faces today. But in today’s globalized world, does the origin of a tree really matter?

  India is well known as a global melting pot of cultures and cuisines. It is also a confluence of biodiversity. Many of the trees that we see in Indian cities came from far-flung corners of the world, including Australia, Brazil, Madagascar, Malaya, Senegal, South America, West Indies and many other locations. Some species like the coconut may have floated in from the sea, passing from island to island and eventually arriving on the Indian coast. Others like the baobab were brought in by slaves and saints, while traders and travellers brought commercially valuable fruit, spice and timber trees. Some trees, such as the tamarind, were brought into India thousands of years ago, certainly before 1000 BC. Others like the rain tree and copper pod are newer imports, coming into India as recently as the nineteenth and twentieth centuries. Some trees were brought as gifts for kings, or commissioned by kings who were keen botanists and horticulturalists, such as Babur and Tipu.

  Colonial botanists built on this tradition, bringing in tree species from their colonies across the world. British, German and Indian horticultural experts planted trees in cities such as Bengaluru, inspired by Kalidasa’s famous treatise Ritusamhara. Trees were carefully selected so that they blossomed serially. The city looked beautiful at all times of the year, with flowers of different colours in bloom. To do this, they had to look across the world for species. Within one location and one type of habitat, trees evolve to fruit and flower at similar times of the year, adapting to their seasonal and ecological conditions as best as they can. But tree planners in cities can free themselves from such constraints.

  City tree-scapes in India are somewhat like paintings, carefully composed by planners and planters from a mixed palette of species from across the world. There is a rich history to these species. If we dig into their origins, we will hear fascinating tales of travellers and traders, merchants, mendicants and rulers who influenced the country. These species, which we refer to as exotics, were brought from distant lands and represent the global influences that have made cities in India what they are today. As with other kinds of global influences, there have also been heated debates about whether exotic trees are a boon or bane. Some writers wax eloquent about the gorgeous visual landscape of cities covered with exotic flowering species. Others complain that native species are slowly disappearing from our urban avenues.

  Part of the debate is cultural. Some tree species that we think of as quintessentially Indian in fact arrived as exotics. Over thousands of years, they have become naturalized to the extent that few remember their exotic origins. Classic examples include the tamarind and the coconut. The tamarind has been around in India for thousands of years. Charcoal remains of the tree have been found in pre-Harappan and early Harappan excavations in India, and it is mentioned in ancient Hindu texts too. Indian cooking is unthinkable without the tamarind, which is an integral part of so many recipes. But the fact remains that it is not a native species and, in fact, originated in central Africa.

  Fossil records of the coconut have been found in the Indus Valley civilization (3100–2800 BC). The fruit is an essential part of Hindu rituals and ceremonies, and is described in post-Vedic texts, such as the Mahabharata. But the coconut also seems to be exotic. The Indian subcontinent is a secondary centre of origin for the coconut, and while there is still some controversy about its source, most experts believe that it originally came from Malesia, a biogeographic region that includes the Malay Peninsula and the islands of the archipelago.

  An Indian landscape is unimaginable without the tamarind and coconut today. But other trees, equally prominent, were introduced by various rulers relatively recently. The Nilgiri Hills were a favourite spot for experimentation with exotic trees. Eucalyptus was brought to Ind
ia by Tipu Sultan in the mid-eighteenth century. The tree is now a firm favourite of foresters and plantation owners, and is found across India in forests, farmlands and cities. The cinchona tree was smuggled out of Peru by a British explorer and planted in the Nilgiris in 1860, with the aim of combating malaria and breaking the South American monopoly over quinine. The Australian black wattle was brought in more recently, in the 1940s during WWII. Its bark was used to tan leather. Another Australian import, mesquite, was introduced in the nineteenth century in Sindh and Andhra Pradesh to provide fodder and fuel to dry parts of the subcontinent.

  Cinchona trees have remained relatively confined to the plantations where they were placed, in part because they were attacked by Indian pests, such as the grub of the cockchafer beetle, and eaten by the Nilgiri sambar, which nibbled down mature trees to sticks in many cases. Eucalyptus, wattle and mesquite, however, thrived and spread beyond the confines of their plantations. These trees have been criticized for being water-hungry exotics. Mesquite and wattle are invasive and have spread into neighbouring forests and grasslands, destroying biodiversity and reducing the water table.

  But these trees are not all bad. They have their uses too. Local villages use all three species for firewood, while mesquite also feeds cattle. Many farmers choose to plant eucalyptus and wattle on their plots for a few years. These trees grow fast, provide an assured income and require little maintenance. At the same time, it is also true that they have spread into many adjacent forests and grasslands, completely changing their structure and function, and in many cases, devastating the local ecology and impacting wildlife. In many cases, invasive plants and trees also impact the livelihoods of local people who depend on forest species suppressed by the invasives.

  India is not unique in its challenges of dealing with invasive species and exotics. A 2002 study by the Food and Agriculture Organization (FAO) of the United Nations found that 1121 tree species were reported to have been taken from their native place of origin to different parts of the world. Many of these introduced species have become naturalized, integrating into their new environments and cultures. But 442 of these were reported as having become invasive, spreading into and impacting native forest ecosystems. These numbers only describe the species that have been studied and written about by scientists. The actual number of exotics and invasives are likely to be much higher. One of the world’s twenty biodiversity targets, laid out by the Convention on Biological Diversity, is to eradicate or control invasive alien species and prevent the introduction and establishment of invasives.

  All exotics are not invasive though. Why do some exotic species become naturalized, while others turn invasive? The answer lies in the connection between the tree and the ecosystem that they inhabit. Species such as the Australian acacia are not invasive in their homelands. They grow and thrive in the right soil and weather conditions, but are also checked from growing out of control by natural predators—herbivores that graze on them, insects that feast on the leaves and seeds, and fungal and bacterial infections that infect trees. When these trees are brought into other countries, either by choice or by accident, they usually travel alone, leaving their grazers, insect predators and microbial pests behind. When they reach their new homes, some species are eaten by local cattle and insects, and thus kept in check.

  Some exotic trees may never be pollinated or dispersed in their new environments, especially if they require specialized bee or bird species to pass on the pollen or disperse the seeds. These species will always be dependent on humans for survival in their new environments. Other trees may be relatively untouched by pests and predators in their new homes. One example is that of the eucalyptus from Australia in India, whose leaves produce strong-tasting chemicals that keep the cattle and insects away. If exotic trees are wind- or water-dispersed, they can spread easily in new environments too.

  These are just some of the factors that influence the spread or control of exotic species. Other traits or characteristics that influence the likelihood of a species to become invasive or naturalized include how deep its roots go in search of water, how fast its fallen leaves decompose, how fast it grows, whether it is taken from place to place by humans and animals, and a number of other factors that the initial introducer may never have thought of. Most countries, now recognizing the dangers of an exotic tree spreading out of control, have put in policies to prevent introductions of foreign plants, trees and animals. (Animals and insects can also be invasive, with equally devastating consequences for local ecology.)

  But the danger of exotics, though raised in earlier times as well, did not deter the European colonial empire, which was focused on finding the ‘best’ location to grow trees from across the world, bringing species from one colony to another. The British were particularly fascinated with South America and the Amazon—lush tropical regimes rich in species they had never seen before. They smuggled the seeds of the rubber plant out of South America, taking it across the world. Some British explorers wistfully said they wished the British had acquired the Amazon instead of India, for the botanical wealth that it possessed. Kew Gardens in London was an important halfway resting house for many of these introduced trees. Seeds and saplings were brought to the gardens, acclimatized and propagated, and then taken to other countries. Many trees and plants moved into India during the British times.

  This was a two-way process. Many Indian species were also moved to other locations. There were several reasons for this transfer. The inexhaustible scientific curiosity of the British led them to take plants they had not seen to London, for Linnaean classification and preservation. Plants were valued for their commercial importance, for their beautiful flowers and as sources of food in new colonies. Acclimatization societies were set up across Europe, beginning with France in 1854. Their goal was to encourage the introduction and naturalization of non-native species in different countries. The British also brought many trees from their homeland into the tropics. British oaks and firs were distributed across city cantonments in different parts of India, planted by homesick British officers and their families who sought to feel more at ease in this alien land.

  The British obsession for aesthetic landscapes led to the import of a number of exotic trees. We see avenues of gulmohar in many cities. This tree comes from the island of Madagascar. The jacaranda with its pale blue feathery blossoms is native to South America. The horticulturalists were enamoured with flowers, but the native peepul and shisham fell out of favour. Some experts raised warnings, asking for caution in selecting and planting the right exotics in the right place, and stating that native trees needed to be preferred as much as possible. But the preference for new imports continued.

  In more recent times, planners and citizens are increasingly beginning to prefer native trees in cities. When heavy rains and cyclones uproot trees, some say that native species survive better, tending to be more deeply rooted. Exotics such as the gulmohar, with their spreading buttress roots, are one of the first to fall in a storm, for instance. But storms may not always make such fine distinctions as we humans do. After Cyclone Vardah lashed Chennai in December 2016, native, exotic and naturalized trees were all uprooted. Gulmohars from Madagascar were felled in the cyclone, but so were the native mango, peepul and banyans, and the naturalized tamarind.

  Exotic trees are also criticized for being water guzzlers in cities and draining an already-low water table. Native trees are commonly believed to provide a more suitable habitat for local biodiversity. Some native species like the peepul also have a cultural and religious identity in Indian cities that help protect them from the axe. A rain tree in the same situation may not be as lucky.

  Flowering exotics are also preferred by some citizens and urban planners, as the flowers add to the beauty of the landscape. In Chandigarh, the eucalyptus has become a focus of recent controversy. While some want the tree to be cut down because it is water-hungry, others want to save it because it is an integral part of the city’s identity. More research need
s to be conducted to reach a conclusion on many of these aspects, as the evidence is largely anecdotal, often differing across locations.

  Our perceptions of exotics sometimes reflect in the tone we use while referring to them—as if we are speaking of an unwelcome, often villainous, arrival in the neighbourhood. In reality, it is difficult to draw clear lines separating the native from the exotic, especially with naturalized trees that have been around for centuries, even millenniums. Certainly, species like the rain tree and tamarind have integrated with the local ecologies, whether urban or rural. A number of birds, animals and insects feed on them and are maintained by their presence. We need to broaden our vocabulary to differentiate between exotic species and the more problematic subset of these that have become invasive, and to integrate naturalized species within our definitions of the native.

  More recently, some scholars have begun challenging conventional wisdom that has created these dichotomies of native and exotic. They say that the animosity towards exotics is a form of indoctrination not supported by strong scientific evidence. They acknowledge the harm that some exotic invasives can cause, but caution that we need to rethink our current bias against all exotics. Cities are novel ecosystems with highly modified landscapes that are in many ways different from the natural ecosystems on which they were built. In such ecologies, isn’t there a role for exotic species?