J - Rare Plant Species

The Pennsylvania Natural Diversity Inventory (PNDI) keeps track of all species in the state determined to be of special concern. Endangered species (PE) are those in danger of becoming extinct in the state. Threatened species (PT) may become endangered if their habitats and populations are not maintained at current levels, while Rare species (PR) are uncommon or restricted in range or numbers. Undetermined species (PU) are believed to be in danger of population decline but currently not enough is known of their range or population dynamics to categorize them as endangered, threatened, or rare. Vulnerable (PV) species are being actively gathered by commercial collectors, while extirpated species (PX) are believed to be extinct in the state. Special population (SP) includes watchlist species for which more information is wanted, species that indicate special habitats, species that host uncommon insects, and species with a restricted distribution in PA.

One Endangered, seven Threatened, two Rare, and one Undetermined species of special concern were found during the survey as shown on the following chart, where “*” indicates that at least one population for that species was known before 2010. Only one of the species was seen at more than one site, and four of them were seen only at the airport. General locations of rare plant species are shown on Maps 3 and 4

Scientific NameCommon NameNo. of SitesState StatusHabitat

Cynanchum laeve

Smooth swallow-wort1PEFields

Alopecurus aequalis

Short-awned foxtail1PTMoist fields

Carex longii

Long’s sedge1PTMoist fields

Chionanthus virginicus

Fringe tree1PTWoods

Hypericum stragulums

St. Andrew’s-cross1*PTDry ground

Juncus biflorus

Grass-leaved rush1*PTWetland

Trillium cernuum

Nodding trillium1PTWoods

Woodwardia areolata

Netted chain-fern1*PTWetland

Andropogon gyrans

Elliott’s beard-grass3*PROpen

Bolboschoenus fluviatilis

River bulrush1PRMarshes
Desmodium nuttalliiNuttall’s tick-trefoil1*PUDry fields

In addition, ten Special Population species were observed in the Township; again, * indicates that at least one population for that species was known before 2010:

Scientific NameCommon NameNo. of SitesHabitat

Allium tricoccum

Wild leeks6*Woodland

Carex conjuncta

A sedge5Moist edge

Carex interior

A sedge1Wetland

Carex molesta

A sedge4Open

Carex nigromarginata

A sedge3*Woodland

Carex striatula

A sedge12Woodland

Cyperus echinatus

Umbrella sedge1*Open

Ipomoea lacunosa

Small white morning-glory3Open

Juglans cinerea

Butternut2Woodland
Nuttallanthus canadensisOld-field toadflax3*Open

Of all twenty-one species, six are found in woodlands, four are wetland species, and eleven are found in fields, meadows, or other open ground dominated by herbaceous plants. They are mostly wide-spread species that are not rare throughout their range, but are at the edge of their range or in a habitat that is disappearing in Pennsylvania. Following are brief descriptions of each species and their habitats:

Allium tricoccum (Wild leeks or ramps) – Special Population 
Wild leek is becoming more common in rich woods in southern Chester County, partly because it is not bothered by deer. Locally abundant in rich woodlands and wooded slopes, especially on gneiss, it is not of special concern in Chester County.

Alopecurus aequalis (Short-awned foxtail) – Threatened, NORTHERN
Short-awned foxtail is a wide-ranging grass that is usually found in disturbed habitats in southeastern Pennsylvania, making it more of a curiosity than an indicator of high-quality habitat. The New Garden site is an abandoned storage area. 


Andropogon gyrans (Elliott‘s beard-grass) – Rare, SOUTHERN
Elliott’s beard-grass grows on infrequently mown, dry upland meadows and banks, usually found with (but almost always less common) than its close relative broomsedge (Andropogon virginicus). Three small populations were observed in the Township. One of the populations, at the New Garden Airport, was quite large in 2006, but had been reduced to a few plants in 2010. In Pennsylvania it is only found in the southeast, and is vulnerable to natural succession and loss of habitat. 

Bolboschoenus fluviatilis (River bulrush) – Rare
A small patch of this rhizomotus sedge growing on the inbound delta mouth of Somerset Lake did not flower, so the identification was not confirmed. In this area it is more commonly found as a fresh-water tidal species. There are no associates that indicate that it was intentionally planted, so it may have been brought in by water fowl.

Carex conjuncta (A sedge) – Special population
This sedge usually grows in small populations on moist roadsides and disturbed ground including pastures, and is underreported rather than uncommon. It was seen five times in this survey.

Carex interior (A sedge) – Special population
A small population of Carex interior was found at the edge of the large pond at Broad Run Ridge. It has also been found in the London Tract marsh in White Clay Creek Preserve – also on Cockeysville Marble – so these two populations are probably related.

Carex longii (Long‘s sedge) – Threatened
Long’s sedge was found in a moist meadow near the railroad on Cockeysville marble. Although it is uncommon or under-reported, it thrives in disturbed areas further south.

Carex molesta (A sedge) – Special population
Four populations of Carex molesta, a sedge of fields, edges, and ditches, were seen in the Township.

Carex nigromarginata (A sedge) – Special population
Carex nigromarginata is a low-growing sedge of dry woods and edges that was seen three times in the Township.

Carex striatula (A sedge) – Special population
This sedge of rich woods and wooded slopes is frequent in Chester County, and really should not be of special concern.

Chionanthus virginicus (Fringe tree) – Threatened
Fringe tree is sometimes planted as an ornamental, but the population at the edge of White Clay Creek is in typical habitat and is almost certainly native. Another small population along Laurel Woods Lane further south also seems native.

Cynanchum laeve (Smooth swallow-wort) – Endangered, SOUTHERN
Smooth swallow-wort can occur as an agricultural weed, in which case it is not considered a rare plant. The population near the railroad is in a relatively diverse but mowed field, making its status questionable. 


Cyperus echinatus (Umbrella sedge) – Special population
Umbrella sedge is usually found in dry disturbed exposed habitats such as roadbanks or old upland fields that are frequently mown.

Desmodium nuttallii (Nuttall‘s tick-trefoil) – Undetermined
A vigorous population of Nuttall‘s tick-trefoil is growing on the steep bank above the airport entrance road. Many tick-trefoils are disappearing in PA because of loss of habitat, and Nuttall’s tick-trefoil will probably be listed as threatened or endangered in the very near future.

Hypericum stragulum (Saint Andrew‘s-cross) – Threatened
Saint Andrew’s-cross is a low growing wiry shrub of open dry soils. The small patch at the airport has persisted in the middle of a dry Andropogon-dominated hay field, and would probably die out if not mowed periodically. This colony is unusual in that it is the only known site for this plant between North Valley Hill, in central Chester County, and the state line, and was not known to occur here until discovered in 2007.

Ipomoea lacunosa (Small white morning-glory) – Special Population, SOUTHERN
This morning glory is not of concern unless it is growing in a native habitat. In southeastern Pennsylvania it occurs only as a weed at the edges of cornfields or highly disturbed bare ground. It was seen three times in the Township.

Juglans cinerea (Butternut) – Special Population
A tree of rich low or floodplain woods, rarely present in any sizable quantity but sometimes overlooked due to a superficial resemblance to its much more common relative black walnut. Several trees were seen near Bucktoe creek and along White Clay Creek. It is of concern because it is threatened throughout its range by a canker disease.

Juncus biflorus (Grass-leaved rush) – Threatened
A large population of grass-leaved rush is growing in a wet meadow at the airport. This species is more often found closer to the Delaware River, and this location is the farthest west found on a township survey.

Nuttallanthus canadensis (Old-field toadflax) – Special Population
A small perennial herb with spikes of small but showy bluish flowers, this plant prefers sandy dry sunny soil with little competition. It was growing several places along the railroad in cinders and dry open soil.

Trillium cernuum v. cernuum (Nodding trillium) – Threatened
This woodland herb favors moist rich woods, frequently growing on the upper edges of floodplains or in lower slopes of woodlands. Once considered frequent, it is a species of concern because of deer predation, and the only population observed in the Township was small with mostly non-flowering plants in a deer-infested woods. There are or were several populations just east of the Township boundary, and there are likely some more occurrences in New Garden Township.

Woodwardia areolata (Netted chain-fern) – Threatened
A small but healthy population of this acidic wetland specialist, first seen several years ago, grows at the edge of a rocky seep near a tributary of Bucktoe Creek.