Today’s India is blanketed with plant species that seem so routine, so much a part of the landscape, it's tempting to think they've always grown here. Some hug the highways, others sprawl across forests, take over ponds, or blanket grasslands. Many are even celebrated for their flowers or shade. But a surprising number of the country’s most invasive alien plants only showed up a few generations ago, hitching rides through colonial trade, botanical experiments, and forestry projects.The story is messier than simply “plants from Britain.” Actually, a lot of these invaders are from the Americas, Africa, or other corners of the world, and then made their way to India through vast British colonial networks. By the late 1700s, the East India Company’s botanical garden in Calcutta had turned into a halfway house for plant species from everywhere.Some were brought in on purpose, say to decorate, supply timber, or provide fuel, while others just slipped in unnoticed. India’s National Biodiversity Authority has counted 168 invasive alien species, with 54 on land and another 56 in water.Here’s a close look at seven plants whose history tells you exactly how colonial-era plant swapping hijacked India’s environment: