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Grasses of the Eloise Butler Wildflower Garden

The oldest public wildflower garden in the United States

Western Panic Grass

Common Name
Western Panicgrass (Hairy Panicgrass, Tapered Rosette Grass)

 

Scientific Name
Dichanthelium acuminatum (Sw.) Gould & C.A. Clark

 

Plant Family
Poaceae (Grasses)

Garden Location
Upland

 

Prime Season
June and July-Sept.

 

Grass structure and definitions - PDF from Oregon State University

Ligule Types, Shapes & Margins (pdf)

 

Western Panicgrass is a common name for the D. acuminatum classifications that are generally known as Tapered Rosette Grasses or Hairy Panicgrasses. This species is widespread across North America.

Western or Hairy Panicgrass is a tufted perennial with long hairy stems. There is extensive variation and overlap between the 10 subspecies in leaf hairiness and leaf dimensions, and this species also crosses with several other species of Dichanthelium.

Stems: Basal rosettes are well-defined, stems range from 15 to 100 cm and can be weak to fairly stout and rigid, early stems are usually not branched but multiple stems rise from the base. Stem nodes are sometimes swollen and may or may not have fine hair on the nodes. Likewise the stems may be clear of hair or have hair of two lengths. Stem color varies greatly. Stems produced in the fall are usually branched and low-lying with many leaf blades.

Leaves: Leaf blades vary from 4 to 10cm long (1.6 to 3.9 inches).

The inflorescence is a tapered panicle ranging from 1/4 to 3/4 times as wide as long. Panicles are open - 3 - 12 cm long (1.2 to 4.7 inches). Spikelets are without awns. Glumes are usually hairy. These plants have two periods of blooming. Primary flower heads are produced in June and early July. Fruiting begins in mid-June. Secondary flower heads come from the leaf axils from July through September. The secondary flowers remain closed and are self-pollinated and produce more seed than the first flowers.

Subspecies: In Minnesota 3 subspecies of the 10 recognized subspecies occur in various counties of the state, widely spread.

Subspecies fasciculatum has wider leaves that are spreading to ascending - 1/4 to 1/2 inch (6 to 12 mm) wide, (more than 8x longer than wide), upper leaf surface hair is less than 3mm. Underside is densely hairy. The flower spikelets are the longest of the 3 subspecies - 1.5 to 1.8 mm long. Lower stems and leaf sheaths have ascending hairs.

Subspecies implicatum has leaf blades 2 to 6mm wide, blades are erect to ascending to spreading to reflexed. Upper leaf surface hairs are 3 to 6mm long, or the surface may be smooth, the underside is densely hairy. Spikelets are 1.3 to 1.6 mm long, obovoid in shape.

Subspecies lindheimeri has stems and lower sheaths that are usually smooth or only sparsely hairy. Upper leaf sheaths are smooth and without hair. Upper leaf surfaces are without hair, lower surfaces may also be smooth or with only soft hair. The panicle is less than twice as long as wide with spikelets ascending to diverging. Spikelets are 1.3 to 1.6mm long and obovoid in shape. Leaf blades are usually yellowish-green and the margins have long fine hair at the base.

 

Habitat: Hairy Panic Grass grows in a variety of habitats, from dry to wet open woods of sandy to clayey soils, in bogs and swamps, and this has lead to the many defined subspecies. Propagation is by seed as the plants do not have stolons or rhizomes.

Names: The genus Dichanthelium is derived from two Greek words, di, meaning 'two' and anth for 'flowering, together meaning twice flowering. The species acuminatum means 'tapering to a point' and may be a reference to the pointed blades. The author names for the plant classification are in two parts. The first to classify - ‘Sw.’ refers to Olof Swartz (1760-1818) Swedish botanist who was a specialist in orchids, who had a botanical collection of 6000 specimens. His work was amended by 'Gould & C.A. Clark'. ‘Gould’ refers to Frank Walton Gould (1913-1981) American Agrostologist, ending his career at Texas A & M University where he was head of the Tracy Herbarium. He authored 80 papers on grasses and four grass manuals including the textbook Grass Systematics. "C.A.Clark' refers to Carolina A. Clark. The pair published via the Missouri Botanical Garden, in 1978, Dichanthelium (Poaceae) in the United States and Canada.

See bottom of page for notes on the Garden's planting history, distribution in Minnesota and North America, lore and other references.

Western Panicgrass Western Panic Grass drawing

Above - note the hair on the stem and the long-pointed leaves. Photo above and at top left ©Anna Gardner, Iowa State University. The drawing is of subspecies Dichanthelium acuminatum var. fasciculatum, from Britton, N.L., and A. Brown. 1913. An illustrated flora of the northern United States, Canada and the British Possessions. 3 vols. Charles Scribner's Sons, New York. Vol. 1: 153.

Below: Details of the spikelets, photo ©Anna Gardner, Iowa State University.

Spiklets

Notes:

Notes: Two species of Panicgrass are found at Eloise Butler. This species, D. acuminatum, and Scribner's Panicgrass, D. oligosanthes.

References and site links

References: Plant characteristics are generally from sources 1A, 32, W2, W3, W7 & W8 plus others as specifically applied. Distribution principally from W1, W2 and 28C. Planting history generally from 1, 4 & 4a. Other sources by specific reference. See Reference List for details.

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