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Dichanthelium hirstii (Swallen) Kartesz

Order: Poales

Family: Poaceae

Dichanthelium hirstii (Swallen) Kartesz

Synonymy: Panicum hirstii Swallen; Dichanthelium dichotomum (L.) Gould var. roanokense (Ashe) R. LeBond

Lower Taxa: none

Origin: Native dichanthelium hirstii

Habit: Perennial, rosette forming grass

Habitat: Wetlands; Outer Coastal Plain peri-glacial depressions

Range: Outer Coastal Plain; PB Atlantic and Burlington Counties

Frequency: Endangered

Rank/Status: S1/G1

Wetland Status: OBL

Flowering & Reproduction: Early Summer, June-early July, vernal panicles, autumnal panicles late July-September; spikelets mature within month of pollination

Comments: Dichanthelium hirstii is a cespitose rosette panic grass found in two small populations in Burlington and Atlantic Counties. Both populations are in or associated with circular depressions formed in peri-glacial environments. The plant is relatively robust for the genus, towering over nearby Panicum rigidulum specimens. Its narrow raceme-like spike and distinct spikelets distinguish this species from any other in the genus. It was discovered by Bob and Frank Hirst whose name is applied to the species. It was initially confined to a few colonies in Central Atlantic County but a new population was discovered by PBC and FNJP members in Burlington County’s Wharton State Forest. Outside of New Jersey, the plant is limited to four counties: Sussex County, Delaware; Oslow County, North Carolina; and Miller and Calhoun Counties, Georgia (USDA 2014).

Unlike the FNA treatment, FNJ does not subscribed to the recent lumping of Dichanthelium hirstii into one polymorphic species Dichanthelium dichotomum. Habitat distinctions, extreme morphological differentiation and other obvious ecological features clearly form a basis to segregate this species from any other affiliation.  USFW (1980 Federal Register) assigned this plant to a hybrid status, between Panicum hemitomom and Panicum {Dichanthelium} spretum.

Reference Specimen: [To be provided.]

Current distribution map reflects author, FNJP members and Mary Hough, 1983.

JRA, 1/2015


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