Northeastern Bulrush

Scirpus ancistrochaetus

Northeastern bulrush (Scirpus ancistrochaetus) is known from MD, MA, NH, PA, VT, VA, WV and Ontario. It is a tall, leafy bulrush (Photo 1) within the sedge family (Cyperaceae), growing from 8 to 12 dm in height with flowering stems (culms) originating from rhizomes. The flowerheads (Photo 2) are umbellate in shape and have downward arching rays when mature. Flowering occurs from mid-June to July, with fruiting through September. Fruits consist of tiny achenes ranging from 1.1 to 1.7 mm long (Rhoads and Block 2007). A diagnostic trait of the species is the achene’s 6 barbed bristles with bristle tips that are shorter, and more pointed that Scirpus atrovirens, a closely related species.

Photo 1 – Scirpus ancistrochaetus, Tioga County, PA (Sept. 3, 2007)


Photo 2 – Northeastern bulrush inflorescence, Tioga County, PA (August 22, 2004)

Scirpus ancistrochaetus grows in seasonal (vernal) pools, small ponds, beaver dams and other depression-related wet areas. The species seems to prefer areas that are inundated with shallow water, or at least saturated, throughout much of the growing season. Aqua-Terra Environmental Ltd. has observed Scirpus ancistrochaetus within 6 or more different wetlands in Tioga County, PA (Drasher, unpublished data). These wetlands can best be characterized as seasonal pools with approximately 33-66% of the depressed basin vegetated with emergent species (Photos 3 and 4). According to Fike (1999), these wetlands are vegetated vernal ponds. Heavily vegetated portions of these Tioga County wetlands resemble an inundated marsh surrounded by deciduous forest. Our observations indicate that the species tolerates dormant season inundation to an approximate depth of 5 dm. Openings within the tree canopy seem to be preferred to allow for adequate sunlight. We have not observed northeastern bulrush growing in the ‘classic vernal pool’ (i.e. leaf-covered basin, 3-10 dm deep, seasonally perched water table, dry by early to mid summer).

Scirpus ancistrochaetus was federally listed by the U.S. Fish & Wildlife Service (USFWS) as endangered in 1991. At the time of federal listing, only 33 populations were known in 7 eastern states (Copeyon 1993). Twenty-two of these populations were in Pennsylvania. The USFWS is considering federal reclassification since enough new populations of the species have been identified since 1991. The northeastern bulrush is currently listed as a state endangered species by the Pennsylvania Department of Conservation and Natural Resources (DCNR) and is proposed for a downgraded listing to threatened. The following native plant status codes and definitions for northeastern bulrushare found within the PA Natural Heritage website.

Global Rank: (G3) Secure
Common, typically widespread and abundant.  Typically with considerably more than 100 occurrences and more than 10,000 individuals.

State Rank: (S3) Vulnerable
Vulnerable in the state either because rare and uncommon, or found only in a restricted range (even if abundant at some locations), or because of other factors making it vulnerable to extirpation.  Typically 21 to 100 occurrences.

Pennsylvania Current Status: (PE) Pennsylvania Endangered
Plant species which are in danger of extinction throughout most of their natural range within this Commonwealth, if critical habitat is not maintained or if the species is greatly exploited by man.  This classification shall also include any populations of plant species that have been classified as Pennsylvania Extirpated, but which subsequently are found to exist in this Commonwealth. 

Pennsylvania Proposed Status: (PT) Pennsylvania Threatened
Plant species which may become endangered throughout most or all of their natural range within the Commonwealth, if critical habitat is not maintained to prevent their future decline, or if the species is greatly exploited by man.

Federal Current Status: (LE) Listed Endangered
A species which is in danger of extinction throughout all or a significant portion of its range.

Photo 3 – S. ancistrochaetus within a vegetated vernal pool (Tioga Co., PA Sept. 2, 2007)


Photo 4 – S. ancistrochaetus occurs within this wetland (Tioga Co., PA Sept. 3, 2007)