Plant of the Week: Swamp Rose Mallow

EnlargeThe seed heads of the swamp rose mallow add texture to the High Line's winter garden. Photo by Juan Valentin

The High Line’s planting design is inspired by the self-seeded landscape that grew up between rail tracks after the trains stopped running in the 1980s. Today, the High Line includes more than 300 species of perennials, grasses, shrubs, and trees – each chosen for their hardiness, adaptability, diversity, and seasonal variation in color and texture. Some of the species that originally grew on the High Line’s rail bed are reflected in the park landscape today.

EnlargeSwamp rose mallow in summer. Photo by Eddie Crimmins

This week we share one of our gardeners’ current favorites with you.

Hibiscus moscheutos ssp. palustris, the swamp rose mallow, is a year-round star of the wetland plantings on the Diller – von Furstenberg Sundeck. It is hard to miss in the summertime, thanks to its huge (up to six inches) saucer-shaped pink flowers. Although each flower only opens for one day, the plant continues to produce blooms throughout the season. It has stand-out leaves, which spread to the size of a large hand and have a smooth, velvety texture. These large leaves and flowers give the swamp rose mallow a tropical feel, but it is a great New York native, with many cousins native to warmer climates. This fast growing herbaceous perennial can reach more than six feet tall, and grow almost as wide, producing a shrub-like habit. Where it has space it can spread easily and colonize large areas.

Once pollinated, these spectacular blooms transform into beaked seed capsules that turn brown, and darken throughout the winter. Each pod contains a ring of seeds that burst open as they mature in the fall – the open capsules will persist throughout the winter. The strong stems of this plant are capable of remaining intact and upright even through heavy snows; their long dark forms stick out of the snow with a beautiful crown of seed capsules, creating a stark contrast with the white surface below.

This spectacular plant is native to most of eastern North America and can be found as far west as Utah. It is no surprise that it has been in cultivation since 1700, its incredible flowers catching the eye of early colonial gardeners such as Thomas Jefferson. It is an important source of nectar to many native pollinators, including the bumblebee and the rose mallow bee. This bee is a specialist pollinator, meaning it depends solely on the swamp rose mallow for sustenance, and it is the only bee that consumes the pollen as well as the nectar. The swamp rose mallow also supports many native butterfly species, including painted ladies and skippers.

WHERE TO SEE THIS PLANT
The swamp rose mallow can be found on the Diller – von Furstenberg Sundeck on the High Line at 15th Street.

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