Plant of the Week: Foxglove beardtongue

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

Penstemon digitalis or foxglove beardtongue is a native perennial found in the eastern half of the United States. It reaches bloom early in the growing season, from about mid-May through June, on tall stems rising up from a rosette of elongated green leaves at its base. Although we are far removed from summer, Penstemon digitalis still adds ornamental interest to the wintery landscape. It grows best in full sun, open fields or woodland edge conditions with well-drained soil. It also tolerates disturbed soils quite well and tends to hold up really well in the colder northern USDA zones.

This straight species has clusters of white tubular flowers at the upper part of its stem. The bell-shaped flower has a tuft of tiny hairs on its fifth lower stamen, earning its name "beardtongue." Penstemon digitalis' unique shape attracts long-tongued pollinators like honeybees, bumblebees, butterflies and even hummingbirds. Though it is not a fragrant flower, Penstemon digitalis' long bloom period, height and attractive inflorescence, make it a great option for a wildflower garden.

Post its peak in early summer, Penstemon digitalis' foliage tends to turn shades of maroon, giving the perennial some fall interest. The flowers leave behind clusters of small seed capsules containing hundreds of seeds which persist into the winter months. Here on the High Line, the absence of fall cut back allows for such winter displays. After our recent winter storm Jonas, where snow accumulated in some areas over 24 inches, Penstemon digitalis was still able to stand tall and add character to the snow covered planting beds. The dark brown seed heads are attractive enough to keep around the garden until spring, when new growth starts to flush out.

Aside from ornamental and environmental benefits, the roots and foliage of Penstemon digitalis, including the rest of the Penstemon genus, all share a medicinal application. The few recorded uses have been said to treat toothaches through chewing of the root as well as an astringent and used for tooth fillings (Runkle and Roosa, 1989). The foliage of Penstemon grandiflorus, a relative of digitalis, has been applied as a wet compress to rattlesnake bites as an absolute antidote (USDA Natural Resource Conservation Service).

Plant Penstemon digitalis in full sun condition but it can tolerate some dappled shade. Avoid planting in clay since it prefers well drained soil. It can also tolerate dry conditions once established but chlorosis will affect the foliage. Tends to be hardy and has little trouble with disease. Tolerates somewhat acidic soil pH and can thrive in nutrient deficient soils.

Eastern Rail Yards

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