Poplars locally called cottonwood tree are fast-growing, weak-wooded trees that lack ornamental flowers and fruits. Many species are native to the U.S. and prefer moist soils.
Some poplars grow more than 70 feet tall and the deciduous leaves are alternate, simple and usually have coarse toothed margins. The trees have a yellow fall color.
Wind-pollinated flowers usually appear in the spring before leaves unfold during March to May. Trees have either male (staminate) or female (pistillate) flowers that are located in drooping catkins.
When fruits mature, the capsules split open and release small seeds attached to silky hairs that assure wind dispersal. The cotton-ball appearance of the groups of seeds is responsible for the name cottonwood, which is applied to some species. Pollen is considered moderately allergenic.
In Minnesota and the southwest U.S., poplars are reported to be important causes of allergies. A common misconception is that the trees are pollinating when they release their “cotton fluff” into the air.
This release comes after the trees have actually pollinated. Cottonwood, Poplar (Populus) is a genus of the salicaceae family.
This genus includes the following allergenic species: Balsam Poplar (Populusbalsamifera), Big-Tooth Aspen (Populusgrandidentata), Black Poplar (Populusnigra), Eastern Cottonwood (Populusdeltoides), Fremont’s Cottonwood (Populusfremontii), Narrow-Leaf Cottonwood (Populusangustifolia), Quaking Aspen (Populustremuloides), Swamp Cottonwood (Populusheterophylla) and White Poplar (Populusalba).
Proteomic analysis was used to generate a map of Populusdeltoides and identified 178 distinct proteins from 218 protein spots expressed in mature pollen. Moreover, out of these, 28 proteins were identified as putative allergens in poplar tree.
During summers, populous deltoids—female poplar—sheds a cotton-like material carrying seeds that cause allergy and aggravate respiratory disorders. This cotton has become an irritant in the recent past for the locals as well as tourists.
The name “Russian poplar” is a misnomer and has nothing to do with Russia. The variety of poplar trees was introduced in Kashmir in 1982from the US.
Locally called as RussiFrass, the species takes less time (10-15 years) to grow, as compared to the Kashmir poplar that takes 30-40 years. However, experts say that the Kashmiri Poplar is harmless.
Due to their high yield, poplars are intensively used inthe timber and construction industry. However, due to cotton-like seeds that the species produces, it has become a pressing problem for the Valley.
“It certainly aggravates respiratory diseases, the cotton-like substance is an irritant that causes allergies,” says ParvaizSajjad Shah, a doctor who treats lung patients in north Kashmir.
“The irritation caused by the pollen results in running nose, red and watery eyes,” he adds.
The cottonwood is a pollinating tree causing allergies that appear seasonally during early spring, with pronounced reactions occurring on warm, breezy days when pollen and mold counts peak due to airborne transport, resulting in inhalation of pollen particles through the eyes, nose and mouth.
Sensitized individuals that inhale cottonwood pollen may become symptomatic with allergic sinusitis, identified by stuffed up nasal passages and sinuses, ear infections, facial tenderness, localized headache pressure above the eyes that may lead to a migraine, fatigue, mood changes, decreased appetite and insomnia.
Allergies to cottonwood produce symptoms of hay fever, causing itchy sensations in the eyes, nose, throat and mouth, accompanied by post-nasal drip symptoms of runny nose, watery eyes and sneezing.
Cottonwood allergies may cause allergic conjunctivitis of the eyes, leading to intensely itchy, watery eyes and eyelids that are visibly red, swollen, bloodshot and tender to the touch.
Allergies to cottonwood may cause symptoms of allergic rhinitis that combine with allergic asthma, resulting in nasal congestion, chronic sneezing and coughing, wheezing, throat soreness, chest tightness and asthma attacks.
The Jammu Kashmir High Court has recently issued another order asking for removal of Russian poplars across the Kashmir valley. Responding to the order, the state government, on June 7, 2015, said that “the order will take time to be implemented”. The pollen seeds of these trees are said to cause respiratory problems.
People with allergies to cottonwood typically display allergies to other pollinating trees and should avoid outdoor exposure on high pollen count days. Decongestants, oral antihistamines, inhalers and allergy injections are effective in reducing cottonwood allergy symptoms.
Underscoring their potential threat to human health, the Jammu Kashmir high court had, on May 5, 2015, said that tehsildars would be responsible for ensuring compliance with the orders passed by deputy commissioners for felling of the trees.
In April, the court had issued another order that was not implemented, following which the court directed the government to implement the order at the earliest possible and wherever necessary.
Knowledge of these identified allergens has the potential to improve specific diagnosis and allergen immunotherapy treatment for patients with poplar pollen allergy.
Author is Research Scholar FOF, SKUAST-Kashmir