What explains Delhi’s love affair with palm trees?

Subject :Environment

Context-

Underneath the Lajpat Nagar flyover in South Delhi is a group of newly planted palm trees that are far away from what would have been their natural home – California in the United States.
The species, Washingtoniafilifera, with fan-shaped leaves and a stout trunk, commonly called the ‘California fan palm’, is the newest addition to the city’s greenscape.
The palm trees under the flyover will soon be joined by the Chinese fan palm or Livistona chinensis, a small tree that is native to subtropical parts of China and Japan.
On Lodhi Road, the Chinese fan palm and foxtail palm (native to Australia) are among the species that are being planted.

California fan palm

Scientifically known as Washingtoniafilifera, the desert fan palm, California fan palm, or California palm, is a flowering plant in the palm family Arecaceae, native to the far southwestern United States and Baja California, Mexico.
Growing 15–20 m (49–66 ft) tall by 3–6 m (10–20 ft) broad, it is an evergreen monocot with a tree-like growth habit.
It has a sturdy, columnar trunk and waxy, fan-shaped (palmate) leaves.

Frond of the problem

Palm trees serve a purely ornamental purpose and are only for beautification.
These are usually planted along with other trees that have more of a role to play — like those that give shade.
These palms (California and date) survive in Delhi, but they need proper maintenance.
Experts say the palms don’t serve much of an ecological purpose in Delhi.
The purpose of urban plantations is that they should have an ecological function and serve as a filter for air pollutants.
The Washingtonia palm neither adds to the beauty of the landscape nor does it provide an effective filter for air pollutants.
Delhi already has an existing issue with the vilayatikikar or the Prosopis juliflora, a non-native,invasive species planted in Delhi by the British.
Thevilayatikikar, a tree native to Mexico, has taken over much of Delhi’s Ridge, suppressing the growth of other, native plants.
juliflora has been included in the Global Invasive SpeciesDatabase (GISD 2010). It has been listed as a noxious weed in all Australian states and in Hawaii.

Description of Vilayatikikar or Prosopis juliflora-

Prosopis julifloratree is native to Mexico.
It is a thorny shrub 3-5 m or tree growing up to 15 m in height.
It has a thick rough grey-green bark that becomes scaly with age.
The plants are often multi-stemmed and furnished with abundant large and very sharp thorns measuring up to 5 cm.
The tree is deeply rooted.
The stems are shaped in a “mild zigzag” way with one or two stout thorns at each turn of the stem.
Leaves are (bipinnatetwice-compound ) with mostly two, sometimes more pairs of pinnae, 6-8 cm long, 12-25 pairs of oblong leaflets per pinna, 6-16 mm long, 1.5-3.2 mm wide.
The flowers are fragrant golden-yellow,dense spikes about 5-10 cm long.
The fruit of P. juliflora is a cylindrical or slightly irregularly curved green pod which turns yellow upon ripening.
It is 10-20 cm long, sweet to taste and contains 10-20 hard oval or elliptic seeds (2.5-7 mm long) that are difficult to extract.
Its roots are able to grow to a great depth in search of water: in 1960, they were discovered at a depth of 53 meters (175 feet) at an open-pit mine near Tucson, Arizona putting them among the deepest known roots.
This plant reproduces through seed.

Uses-

Various Prosopis species have beneficial qualities which include erosion control, shade, fuelwood, building materials, and pods for animal and human consumption in arid and semi-arid regions.

Environmental concern-

The fact that there are clear economic uses for this species but severe negative consequences of P. juliflora invasion makes this a conflict of interest species.
Concern over the tree is it does not let any other tree or shrubs survive around it.
These trees can dry up underground aquifers through their deep-root system, going as far as 20 metres or more in search of water, significantly higher than around 5 metres that native shrubs and trees go.
The tree’s canopy is such that it does not let sunlight reach the ground, which also hinders growth of other species.

Some of Delhi’s palm trees-