The name for the genus comes from the Greek words meaning two-flowering, and refers to the 2 flowering periods of these grasses, once on the primary stalk in the spring and again on the branches in late summer (Flora North America Editors 2003). The species name means broom-like (Fernald 1950). This species is in the section Clandestina with two other related species, Dichanthelium clandestinum, the common deer-tongue grass, and the New York rare grass Dichanthelium scabriusculum.
There are three existing populations. On Staten Island however it has been suppressed by woody succession in the last 20 years and may only survive in the seed bank waiting for the right disturbance. There are five historical populations from the early 1900s through the 1950s which have not been rediscovered although habitat still exists. There are two populations that are now considered extirpated because their habitat has been developed.
Although this plant was always rare with fewer than 10 occurrences documented in the state it has now been reduced to one population which may or may not still be there. More intensive surveys may discover new populations since this plant is difficult to positively identify.
This species needs disturbance to reduce competition from woody plants or more aggressive herbaceous plants but too much direct disturbance to the plants will reduce or eliminate the population. Its habitat could be disturbed in the non-growing season to reduce competition to allow for seed germination and colonization but direct disturbance should be prevented during the growing season.
Research is needed to determine the proper disturbance regime for this grass.
The only extant site for this species in the state is a grassland on serpentine soils. However, the historical record shows collections from non-serpentine wetlands in the New York City and Long Island areas (New York Natural Heritage Program 2010). Moist, sandy, often disturbed areas (FNA 2003). Wet soil (Gleason & Cronquist 1991). Damp thickets, swales and shores (Fernald 1970).
This grass is only currently known from Staten Island and Long Island. There are also some historical records from the Finger Lakes area in Seneca, Tioga, and Yates counties.
This grass occurs along the coastal plain from Massachusetts (where it is possibly extirpated) south to northern Florida and the Gulf Coast to Texas. It also occurs inland from Virginia to southeastern Kansas south through eastern Oklahoma and eastern Texas. There are a few rare populations in the upper Midwest on the southern borders of Illinois, Indiana, and Ohio and one disjunct population in northeastern Michigan.
This species is a perennial grass which forms small clumps. The stems are from 50 to 150 cm tall, soft-hairy throughout, and arise from a rosette of lance-shaped basal leaves. The nodes are swollen, and have a dense "beard" of hairs above a constricted, sticky ring. There are 7 to 11 stem leaves, these also hairy and 9 to 20 mm wide. Both the internodes and the ends of the leaves are purplish. The primary infloresence is a panicle 6-16 cm long and 5 to 12 cm wide, flowering from May to July. The spikelets are 2.2 to 2.8 mm long, prominently veined and pubescent on the margins and apices. The lower florets are sterile, and the upper (fertile) ones sharply pointed on top (FNA 2003).
Plants with stems and fruits (preferably both early and late-season infloresences) are best for identification, though vegetative material may also be identified.
The velvety hairs and swollen nodes with a "beard" of dense hairs above a glabrous, sticky ring are distinctive.
The mature fruits develop from July through October.
The time of year you would expect to find Velvet Rosette Grass fruiting in New York.
Velvet Rosette Grass
Dichanthelium scoparium (Lam.) Gould
Flora of North America Editorial Committee. 2003. Flora of North America, North of Mexico. Volume 25. Magnoliophyta: Commelinidae (in part): Poaceae, part 2. Oxford University Press, New York. 783 pp.
Fernald, M. L. 1950. Gray's manual of botany. 8th edition. Corrected printing (1970). D. Van Nostrand Company, New York. 1632 pp.
Gleason, Henry A. and A. Cronquist. 1991. Manual of Vascular Plants of Northeastern United States and Adjacent Canada. The New York Botanical Garden, Bronx, New York. 910 pp.
Holmgren, Noel. 1998. The Illustrated Companion to Gleason and Cronquist's Manual. Illustrations of the Vascular Plants of Northeastern United States and Adjacent Canada. The New York Botanical Garden, Bronx, New York.
New York Natural Heritage Program. 2010. Biotics database. New York Natural Heritage Program. New York State Department of Environmental Conservation. Albany, NY.
New York Natural Heritage Program. 2020. New York Natural Heritage Program Databases. Albany, NY.
Weldy, T. and D. Werier. 2010. New York flora atlas. [S.M. Landry, K.N. Campbell, and L.D. Mabe (original application development), Florida Center for Community Design and Research http://www.fccdr.usf.edu/. University of South Florida http://www.usf.edu/]. New York Flora Association http://newyork.plantatlas.usf.edu/, Albany, New York
This guide was authored by: Stephen M. Young
Information for this guide was last updated on: March 1, 2012
Please cite this page as:
New York Natural Heritage Program. 2020. Online Conservation Guide for Dichanthelium scoparium. Available from: https://guides.nynhp.org/velvet-panic-grass/. Accessed July 16, 2020.