Spring is here: a splash of colours amid Delhi’s concrete jungle

Pradip Krishen, environmentalist and author of Trees of Delhi, sheds light on Delhi’s floral delight

With the onset of spring, which major flowering trees can one find in Delhi and how many are there at present?

It’s important to understand that all trees flower, even the conifers. So one answer is that, all 252 species of trees that I described in my book plus a few more that have been introduced since then, are all flowering trees.

At this particular time, late in March, the most eye-catching flowering trees are the dhak, kachnar, the Caribbean trumpet tree, the Indian coral tree, mango, kanak champa, the weeping bottlebrush, the chestnutleaf trumpet-bush and the Jerusalem thorn. There will be another wave of flowering in April-May.

When it comes to ‘eye-catchyness’, I personally think that some of the trees that are flushing with new red leaves right now are hard to beat. The pilkhan at this time is looking magnificent and is changing colours every day. So is the kosam.

2. Are all of them indigenous species or are there foreign varieties too?

Delhi has a ragbag mix of indigenous and exotic trees. Some of the exotics, but by no means all of them, are invasive, none more so than the vilaiti kikar, which has carved out its own kingdom on the Ridge by edging everything else out. My guess would be there are not much more than 35 or 40 indigenous species, most of them growing forgotten in some neglected patch of semi-wild forest in Delhi.

3. Which are the most common invasive species that have gained dominance over the indigenous ones?

Apart from vilaiti kikar, we’re threatened big time by su-babool, which is even more aggressive and no one, least of all any of our horticulture or forest authorities, have woken up to the way it is out-competing other trees and creating dense woodlands of its own. We’ve already given up the war against vilaiti kikar. It’s important to take up cudgels against su-babool but no one is paying attention.

4. Has rapid urbanisation or sheer neglect led to a decline in trees?

It’s not at all clear about declining numbers. Forest surveys report a slight increase in tree cover, but this is satellite data with no attention paid to the quality of tree cover. The data might be all about increasing vilaiti kikar and su-babool.

At the same time, it’s absolutely true that there is negligence by the civic authorities. I’m not proud of the horticulture establishments we have in this city. They seem to be enamoured by the way landscapes are planted up in Sharjah and Dubai with palms and drip-irrigation. How sad that a country so rich in native trees tries to emulate a desert kingdom.

5. Any other interesting anecdote or trivia on Delhi’s floral delight that sustains itself in this concrete jungle?

Have you ever wondered why trees flower at this particular time of the year? The answer is more complicated than ‘because its spring’. In a nutshell, in Delhi’s climate (with only a single pulse of rain in the monsoons), the only feasible time for a tree to ripen its fruit is to be in sync with the rains. So a tree needs to count backwards from the onset of the rains. If it needs two months for its fruit to ripen, and another month before that for its flowers to develop and be fertilised, then the best time for flowering is three months before the rains come in the middle of July. That makes it middle of April.

All trees need to do this arithmetic. The reason there is some variation is because it takes different amounts of time for fruit to develop. But it's lovely to understand that nature works with great precision and logic, don’t you think?