Species of Conservation Concern

A white bog orchid with multiple blooms on one stem.
A white fringed orchid found on a plant expedition in Luzerne County, PA, in 2020.

Preserving rare and endangered plants, also known as species of conservation concern, encompasses both the need to prevent the extinction of species, and to make sure that there is enough genetic diversity within a species so it can be resilient to future threats from pests, pathogens, or environmental changes.

We are committed to finding and saving these plants by working with partners around the globe to find, grow, and propagate threatened plants so they can thrive, ensuring continued plant biodiversity and healthy ecosystems.

 
A orchid with purple blooms growing in a forest.

Platanthera peramoena (purple fringeless orchid) is among the native plants we will be working to preserve in ex situ conservation. We chose this species because it is known to enter “prolonged dormancy,” a condition well-documented in orchids. This means it doesn’t appear or flower every year. We hope that our efforts to collect seeds of this species will provide an additional means of conserving this species and provide more information about its behavior. Photo by Peter Zale.

As we assess new species, we are identifying their conservation value. Some examples from our collection include:

  • Appalachian Jacob’s-ladder (Polemonium vanbruntiae)
  • box huckleberry (Gaylussacia brachycera)
  • Canby’s mountain-clover (Paxistima canbyi) 
  • Kate’s Mountain clover (Trifolium virginicum)
  • greater lady’s slipper (Cypripedium parviflorum var. pubescens)
  • Kentucky lady’s slipper (Cypripedium kentuckiense)
  • Leonard's witch-hazel (Hamamelis ovalis) 
  • mountain-parsley (Taenidia montana) 
  • purple fringeless orchid (Platanthera peramoena) 
  • showy lady’s slipper (Cypripedium reginae)
  • spreading rockcress (Arabis patens) 
  • tuberous grasspink (Calopogon tuberosus)
  • white fringed orchid (Platanthera blephariglottis)
  • yellow fringed orchid (Platanthera ciliaris) 

Conservation Spotlight: Leonard’s witch-hazel

A small white-green leaf on top of a big green leaf of the big leaf witch hazel plant.
Leaves of Leonard’s witch-hazel are two to three times larger than the common eastern witch hazel. New leaves appear white.

While you may only think of rare and endangered plants in the Amazon rainforests or other remote parts of the world, endangered plants are everywhere.

One example is our work with Leonard's witch-hazel (Hamamelis ovalis), through a project led by members of the US National Arboretum. We traveled to Southeastern parts of the US to collect samples of this rare plant from the wild to be propagated. 

In 2023, we visited Texas to study a population that had notable diversity in flower color and plant form. However, upon returning in 2024, it was discovered the site had been clear-cut for logging. The trip quickly became a rescue mission. The team salvaged 10 plants from the clear-cut area and those plants now reside at the US National Arboretum. It is through collaborations like these that we can continue to explore, collect, and conserve plants.

Pennsylvania’s First Seed Bank

Longwood has expanded its seed bank to create Pennsylvania’s first conservation seed bank, specifically designed for the long-term storage of seeds from rare and globally endangered native plants. This seed bank will act as a genetic time capsule, preserving the biodiversity of these species.

Learn more

Reintroducing Rare Pennsylvania Plants

To ensure the survival of rare Pennsylvanian plants and protect against factors that threaten wild populations, we work with collaborators to propagate and reintroduce plants back into the wild. Longwood also serves as an ex-situ conservation site to bank the seeds of these rare and endangered plants.

This process includes field work, seed collection, and seed germination research and is an example of how gardens can use their plant collections to reintroduce plants back into their native habitats.

Conservation Spotlight: Appalachian Jacob’s-ladder 

Tall green grass with a single purple flower in the center of the image.
Appalachian Jacob’s Ladder (Pennsylvania S1/G3) is considered of highest conservation concern in PA and is ranked among third tier plants globally.

Another example closer to home is our work with the Appalachian Jacob’s-ladder (Polemonium vanbruntiae). Known from just seven extant populations—mostly found in two counties in NE Pennsylvania—most of the populations are extremely small, with one population consisting of a single plant. Like any other rare species in PA, it suffers from excessive white-tailed deer browse. 

Working with our partners at the PA Plant Conservation Network, we have been systematically collecting seeds from all populations to research seed germination requirements and learn what is needed to grow this species for ex situ collections and population augmentation. We implemented a small seed germination study in which seeds were given 30, 60, and 90 days of cold, damp conditions. These experiments yielded in excess of 500 seedlings, which proved to be easy to grow and vigorous under long days in our greenhouse.

Within a few months, plants had grown to a size to which they could be planted outside. We worked with the PA Plant Conservation Network to return plants to two of the seed source populations, furthering our work to increase the survival of this species.