FÁSKRÚDSFJÖRDUR, Iceland — In the cool morning air, an assortment of Icelandic warriors headed for their battlefield — armed with long knives and weed whackers.
Their enemy? A field of purplish-blue plants, stretching high up the mountain above, an invader that increasingly dominates and defines coastal scenes in eastern Iceland.
To tourists and plenty of Icelanders the lupine fields are a breathtakingly beautiful sight in midsummer, the attractive blossoms carpeting gorges, sprawling over lava fields and climbing steep mountainsides. But for some natives, the plants are an alien blot on the landscape that need to be eliminated.
And the threat is growing. Encouraged by the warming atmosphere, lupine is spreading beyond Iceland’s relatively temperate coastal areas and into the interior, previously thought too dry and cold to support the plant. Within 30 years, under current climate change forecasts, it could colonize much of the highland interior, shaped by volcanic eruptions and covered in different shades of lava.
There is another downside to lupine. After bloom, the lovely light green foliage and the flowers die an ugly death, fading to dark brown punctuated by prominent, grayish-brown spikes bearing seed pods. In urban areas, where lupines grow on traffic islands and in public parks, admirers of the plants wait for the snow to cover up the mess.
Tensions rose when a community organizer, Anna Samuelsdottir, called for “outlawing” the alien plant from berry lands and natural reserves in eastern Iceland. “I never expected to receive this many letters,” she said, adding that the letters were by and large hostile to her idea.
The flower’s defenders like to point to conditions before lupine was introduced.
At that time, much of the island was ecologically exhausted from overgrazing and slash-and-burn agriculture after 1,100 years of settlement. Only 25 percent of the country’s original green cover remained, they say, and the typically strong winds were blowing what soil was left into the sea.
Besides shutting down the erosion, the Nootka lupine acted like a fertilizer factory at almost no cost. The plant hosts bacteria that gather nitrogen from the air, transferring the gas to its root nodules and providing nourishment for the plants that follow.
“Sand storms would shut the road many times a year before the lupine cover,” said Johannes Gissurarson, a local farmer. He grazes sheep on land enriched by the lupine.
Today, that tableau of desolation has been replaced by waves of purple-blue, a sight that has thrilled tourists for decades along the popular southern Route 1.
One day recently a young couple from Texas posed for an engagement photo amid a field of blossoms near the Skogar waterfall. Dressed elegantly, they posed on top of their SUV to properly stand out from the three-foot tall plants.
Further east on the national road, lupine seeds have — at some point — been tossed into the moss-grown Eldhraun lava field, formed in a historic 18th-century eruption that wiped out a fifth of Iceland’s population.
Iceland is particularly vulnerable to floral invasion, as alien species dominate existing flora and spread rapidly to those places currently without much vegetation.
“Exponential growth is the nature of invasive species,” said Pawel Wasowicz, a botanist and lupine expert at the Institute of Natural History. The growth curve, he estimates, will peak in the next two decades.
Eastern Icelanders have witnessed the lupine creep in real time. Over a 15-year period, the plant has spread up to 35-fold in areas of east Iceland.
“We are at the point of no return,” said Arni Bragason, director of the Soil Conservation Service of Iceland. “The best thing we can do is reach a consensus about where the plant should be. That has been hard, too.”
This past spring, his agency officially terminated its lupine project after 42 years of providing seeds to the entire country. Villagers in eastern Iceland recall being able to grab a free scoop of seeds at gas stations in the early years.
Eradication is difficult. Killing the plant is a three- to five-year process that involves cutting them back at the peak of the bloom, when the plant is putting its energies into the flowers and the roots are correspondingly weakest. Mowing down the plants has proved more effective than herbicides.
Most of the culling is carried out by volunteers. Municipalities have been hesitant to allocate money, given the controversy surrounding the practice.
In the alpine town of Faskrudsfjord in East Iceland, Stefan Elvarsson, 18, was preparing to join a lupine slaughtering party. “When I was young,” he said, as if describing a long-lost way of life in the bustling harbor village, “we did not wade lupine fields to get up our mountain.”