Bad Flora (plants)
Bad Flora (Plants)
Today the world has about three trillion trees, spread across over 58,000 species. India is home of over 2,600 native species, out of these 650 are endemic.
India is also home to hundreds of species of exotic or alien trees, many of them brought over by traders, travelers and later colonial rulers. These include friendly foreigners that have integrated with the local landscape and don't threatened native species such as Tamarind (originally from Africa) the magnificent rain tree and the curious baobab.
Introduction
The proliferation of three rapidly growing tree species of vilayati kikar, sababul and eucalyptus in the capital needs a plan to contain and exterminate them.
Highly poisonous plants: plants to destroy or remove
- Castor oil plant (Ricinus communis) ...
- Coral tree (Erythrina genus) ...
- Common or pink oleander (Nerium oleander) and yellow oleander (Thevetia peruviana) ...
- Deadly nightshade (Atropa belladonna) ...
- Golden dewdrop (Duranta erecta) ...
- Rhus or wax tree (Toxicodendron succedaneum)
Native friendly alien or invasive , Ecological threat
Vilaiti Keekar. Prosopis juliflora also locally as Vilaiti Keekar. (severe drain on water table).
Australian Acacia. (severe drain on water table).
Eucalyptus (severe drain on water table).
Subabul An Acacia tree. (Aggressive invasive weed ) South America. (severe drain on water table).
Ornamental invasive
Lantana (an invasive plant) From America and Africa
Water Hyacinth. A weed. (choke the city's water bodies.)
Parthenium hysterophorus . Congress grass. 'Bangalureans Allergies' caused by Pollen of Parthenium .
Opuntia or Prickly Pear (fast proliferative invasive)
Krishna Siris : Albizia Amara is a middle sized, tree with a feathery canopy, easily mistaken for an Acacia except that it is unarmed. Its leaflets and powder-puff flowers are the smallest of any Delhi albizia.. Seasons : Leaves thinned out in February- March, renewed in early April with another flush of rains. Flowers last through most May. Fruits : ripen in October- November. Flowers : Faintly fragrant, closely placed into spherical heads 1.5-3cm in diameter. The long white stamens are the most prominent part of the flower. Fruit Pod : greyish brown with slightly wavy margin. You can clearly see the seeds as little bumps in the flat pods.
MESQUITE / Vilaiti Keekar
Prosopis juliflora
Mesquite flour is among the earliest known foods of prehistoric man in the Americas. Foliage and pod make good animal fodder. Valued for firewood and fodder for ecologically poor tract, thus a vital resource for poor desert dwelling people. Its wood makes a high quality charcoal and is prized as a barbeque fuel, imparting a subtle flavor to meats and fish.
Superbly adopted to drought heat and poor soils. Vilaiti Keekar is an aggressive colonizer. It obliterated Asia's biggest grassland in the Rann of Kutch planted on a Delhi Ridge early last century, it edged out most native trees. It does not tolerate high rainfall or waterlogging.
Prosopis juliflora is called Vilaiti Keekar, it is different from Babool. It is not even an Acacia. A bush or a medium sized thorny tree or straggling bush with crooked main branches and a spreading , feathery canopy. Young branchlets zigzag. Bark ruddy brown, with long vertical fissures and ridges. Spines in pairs, straight arising from leaf axil.
It is a most harmful an invasive Mexican species, introduced by British in 1930, which has taken over a Delhi ridge. Vilayati kikar forms nearly 70% of all trees in the ridge at present. Its roots grow over 50 meter deep, so it depletes the ground water table wherever it grows. The main problem with it is that it does not allow native species to grow around it.
First introduced from S America on to the Ridge around 1915. It is superbly adapted to Delhi's ecology and has become the city's most common tree by edging out many native species. It is now a serious pest.
Seasons
Leaves :Leaves shed early in January, renewed between late January and early March. New leaves pale green, darkening gradually. Another flush of new leaves in rains. Twice feathered, the main leaf stalk, branching only once or twice (rarely three times). If you look closely the main leafstalk is prolonged beyond the last pair of side stalks into a minute bristle. The leaflets are small (6-19mm) rounded at both end, up to 26 pairs crowded on each side stalk.
Flowers : From mid March to Late April. Another cycle of flowering just after rains. Flowers pale to greenish yellow, very small clustered in small spikes like 'pipe cleaners'4-10 cm arising from leaf axis. The spike may be solitary or in groups of 2-4. They are mildly fragrant and are visited by bees.
Fruit : ripen April- May also in Late October-November. Fruit pod- a flattish pod about 12-25 cm long, variable in shape, usually curved to some degree. Pale green when young, ripening straw yellow. Parakeets love them.
Vilaiti Keekar with its twisted trunks has become the predominant tree throughout the Delhi Ridge,
KOHI Delhi's hilly tracts correspond to 'the Ridge', which is slightly elevated., rocky land form lying in a longitudinal axis west of and more or less parallel to the Yamuna river. Because of its underlying rock and thin sandy soil, The Ridge is a harsh unforgiving habitat and tree growing there need to be specially adopted to survive drought. Characteristic ridge trees are stunted thorny and open canopied. They have long tap roots to search for moisture deep underground and often shallow spreading roots as well. to exploit due and light rain. Vilaiti Keekar has become a ubiquitous invasive tree throughout Delhi, aggressively colonizing any path of bare land
Delhi government plans to remove Vilaiti Keekar.
Delhi's Ridge is in 4 parts today
Delhi's "Ridge" is the tail end - or the beginning, if you like - of the ancient Aravalli hills 1500 million year old (compared to just 50 million for the Himalayas). The Aravallis stretch 800 km from Gujrat through Rajasthan and Haryana, pushing into Delhi from Gurugram to the south west.
- The old Delhi of northern Ridge denotes the hilly areas near Delhi university and is by far the smallest segment of the ridge. Nearly 170 hectares were declared a reserve forest in 1915. Less than 87 hectares remain today.
- The New Delhi of Central Ridge was made into reserved forest in 1914 and stretches from just South of Sadar Bazar to Dhaula kuan. It extend over864 hectares, but some bit have been nibbed away.
- The Mehrauli or South -Central Ridge is centered on Sanjay Vana, near JNU, and encompases633 hectares. Large chunks have been encroached and built upon.
- The Tughlakabad or Southern Ridge Sprawls across6200 hectares and includes the Asola and Bhatti wildlife centuries. This is the least urban of the 4 segments of the ridge, but a lot of it is village- or privately owned farm land.
Saptaparni /Alstonia Scholaris
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| Alstonia scholaris/Black board tree/ Milkwood/Devil tree or /सप्तपर्णी/ शैतान का पेड़ |
October brings with it the onset of Delhi’s winter and the festive season. In this season Saptaparni (Alstonia scholaris) tree is in bloom with a bunch of pale green flowers lying on the ground. It marks the debut of the winter. There’s a change in the air accompanied by a distinct strong smell, which for some of us, is synonymous with this season. It’s from the flowers of the Saptaparni ( Alstonia scholaris ) tree that are small greenish-white, growing in tight clusters that stay until December.
They are first been introduced in Delhi in 1940's and first planted in the then new Golf Links. The gigantic tree stands at the Indi International Center, currently cloaked in thousands of scented flowers. Saptaparni is known by many names, and is the tree from which our blackboards are pigmented.
October brings with it the onset of Delhi’s winter and the festive season. There’s a change in the air accompanied by a distinct strong smell, which for some of us, is synonymous with this season. It’s from the flowers of the Saptaparni (Alstonia scholaris) tree that are small greenish-white, growing in tight clusters that stay until December.
Saptaparni is a medium-sized evergreen tree from the very moist forests of the Himalayas. According to references, the tree was first planted in Delhi in the late 1940s when Golf Links colony was coming up (it’s still a good place to find the tree, along with Lodhi Gardens). It has slowly evolved as a prominent avenue tree, due to its hardy nature, high tolerance against pollution, and adaptability.
The name comes from two Sanskrit words, Sapta meaning seven, and Parni meaning leaves. As the name suggests, the leaves, most often, are found in bunches of seven around the stem. They are blunt, glossy, and create starry symmetries. The leaves remain throughout the year with new flushes standing out against older leaves in March and April and again during the rainy season. The tree’s fruit is bean-like and appears in pairs.
The tree’s natural range shows a broad belt in the sub-Himalayan tract east of the Yamuna and is also found in the moist forests of the Western and Eastern Ghats in peninsular India. In addition to this it also grows naturally from Sri Lanka to Myanmar and South China, and from Malay Peninsula to Australia. “In its natural habitat, it is best suited to deep, moist soil and its tolerance to drier conditions makes it very favorable for Delhi but the growth is often stunted,”
The bark is known as ditabark, used by Indians as traditional medicine to treat diarrhea, dysentery, asthma, and a few types of fevers. It has also been used as an aphrodisiac. When damaged, the bark lets out a sticky milky latex, which is also valued for its medicinal properties. This is used by vaids in formulations, and not to be consumed as is.
Known by many names like Shaitan ka Jhad or the Devil’s Tree, tribals are often reluctant to sit under this tree or even pass under it for the fear of the devil. However, its most important significance comes from its scientific name, Alstonia scholaris. The genus is named after professor C. Alston, a famous botanist of Edinburgh. Students’ blackboards, writing tables and slates are made from the bark of the tree. Hence, the other name for the tree is the Blackboard Tree and also includes the word scholaris in its scientific name.
The Saptaparni is of great cultural significance in the intellectual circle, as traditionally its leaves were awarded to scholars and teachers during convocation ceremonies by the Visva Bharati University. This tradition was started by Rabindranath Tagore in Gurudeb University. Due to environmental degradation, the practice has been reduced to handing over a single leaf to the Vice Chancellor of the University.
The large branches provide favorable breeding sites for wild bees to make their hives and the pollination of the tree is carried out by insects. When the tree flowers, a plethora of insects like butterflies, bees and beetles are seen all over it. The seeds of the tree have a tuft of silky hairs at each end, and are dispersed by the wind.
Why is Saptaparni tree harmful to humans ?
The pollens from 'Alstonia Scholaris' causes asthma, sinusitis, eye related issues and skin allergies also. It is also termed as one of the polluting trees of Delhi.
Sekaash (Saccharum spontaneous)
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Saccharum spontaneum (wild sugarcane, Kans grass) is a grass native to the Indian Subcontinent. It is a perennial grass, growing up to three meters in height with spreading rhizomatous roots . Elsewhere, its ability to quickly colonize disturbed soil has allowed it to become an invasive species that takes over croplands and pasturelands
Why is 'Sekaash (Saccharum spontaneous' harmful to humans ?
The pollens from ''Sekaash (Saccharum spontaneous" causes asthma, sinusitis, eye related issues and skin allergies also. It is also termed as one of the polluting grass.
These also include the aggressive invasive such as Lantana. Brought over by the British as an ornamental shrub 200 years ago. It spreads across forest floors and climb all the way up to canopies, crowding out other plant species.
Eucalyptus
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It is second most unwanted tree in Delhi. Eucalptus come from Australia, it is exotic is not invasive in nature, but uses a lot of water as it is a fast growing tree. Where ever it grows the ground water level will drop rapidly. It also shows allelopathic effects, meaning it releases compounds which makes it difficult for other native species to grow nearby.
Subabul (Leucaena leucocephala)
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The third tree flagged in the list also from Mexico and was introduced by the forest department for fuel and fodder, but it has grown too rapidly, expanding well beyond where it was initially planted. While subabul is not as harmful as vilaitikar, it still propagated quickly,. Like Vilayati kikar, it does not allow native species to grow around it.
, it has become spreading quickly across the city. The tree releases copious amount of seeds and can grow quickly, not allowing any other tree or sapling to grow around it.
Water Hyacinth
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| Water Hyacinth Eichhornia crassipes (A weed). Invade and choke the city's water bodies. |
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| Water Hyacinth |
Water Hyacinth
Lantana
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Which are similarly an invasive specie and multiply rapidly crowding out native species and their symbiotic flora and fauna. in ridge.
Parthenium histerophobius / Poisonous Congress Grass
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Bangalureans Allergies' caused by Pollen of Parthenium .
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