Pictured from left to right: Panicum capillare (2 photos), Panicum lanuginosum, Panicum oligosanthes (2 photos) and Panicum virgatum
This genus has is characterized by 2-flowered spikelets in which the lower floret is sterile and the upper is fertile and hardened. The first glume is often small and easily overlooked and the sterile lemma is similar to the glumes and easily mistaken for one. There are usually some long hairs somewhere on the plants. In our species the ligules consist of a ring of hairs. The perennial species that produce basal rosettes of leaves shorter and wider than the culm leaves and often with secondary branching are sometimes considered as a separate genus called Dichanthelium.
There are 20 species in MN; 18 are native.
Panicum capillare (pan' nih come cap ill air' ee)
- Synonyms: None
- Common names: witch grass, tickle grass; Lakota: ite awicasniyan hu
- Origin and habitat: Native; dry or moist soil, often disturbed places
- Identifying characters: This is a loosely tufted annual with pubescent leaves. The inflorescences are open broad panicles often half or more the height of the whole plant. Spikelets are 1.8-3.5 mm long with acuminate apices. Glumes and florets are generally glabrous or pubescent only at their very apices; the first glume is no more than half the length of the second; the fertile lemma has distinctly inrolled margins covering half the palea.
- Comments: The small fruits and large inflorescence give the plant a misty appearance at maturity. A prolific reseeder, the whole inflorescence breaks easily from the stem and is often blown away or rolls along on the ground while the small fruits dislodged. Witch grass also is spread easily with hay and crop distribution and in bird seed so that it is considered a native weed.
Panicum lanuginosum (pan' nih come lah new jih no' sum)
- Synonyms: Dichanthelium acuminatum, D. lanuginosum
- Common names: woolly panic grass, hairy panic grass
- Origin and habitat: Native; variety of habitats
- Identifying characters: This is a branched tufted perennial with pubescent internodes and usually a basal rosette of leaves. These basal leaves are shorter and broader than the culm leaves, which have blades much wider than their sheaths. The inflorescence is an open panicle often well-separated from the uppermost leaves. Spikelets are 1-2.4 mm long with rounded apices. First glumes are tiny (less than half the length of the second) and glabrous or pubescent; second glumes are pubescent. The fertile lemma is about equal in length to the sterile one, glistening yellow and with margins only slightly inrolled over the palea.
- Comments: Similar to witch grass (P. capillare), woolly panic grass is easily distinguished by a much smaller panicle with spikelets also slightly shorter.
Panicum leibergii (pan' nih come lee ber' gee eye)
- Synonyms: Dichanthelium leibergii
- Common names: Leiberg's panic grass
- Origin and habitat: Native; dry prairies and other open sites
- Identifying characters: A tufted perennial, this species has a felt-like covering of hairs near the nodes and bulbous-based hairs on the leaf sheaths and blade margins. Blades are much wider than the sheaths and ligules are tiny (less than 0.5 mm long). Inflorescences are open panicles with large spikelets (3.1-4.1 mm long) that are long-hairy. First glumes are about half as long as the second and both are pubescent as is the sterile lemma. The fertile lemma is glistening yellow, with margins slightly inrolled and covering less than half the palea.
- Comments: Similar to the other panic grasses, P. leibergii has longer spikelets than P. lanuginosum and the plant hairs are not as dense as in P. capillare
Panicum oligosanthes (pan' nih come ah' lih go san' these)
- Synonyms: Dichanthelium oligosanthes
- Common names: Few-flowered panic grass; Lakota: eji wakan
- Origin and habitat: Native; found in a variety of habitats
- Identifying characters: This is a perennial with tufted stems that have a tendency to sprawl; internodes are purplish and glabrous or sometimes with a felt-like covering of hairs, while nodes nearly always are pubescent. Leaf blades are pubescent on the margins, often with bulbous based hairs and sometimes also with scattered hairs on the upper surface. The blades are much wider than the hairy sheaths and ligules are tiny (up to 1 mm) with hairs of varying length. The inflorescence is an open panicle, often purplish in color. Spikelets are 2.7-4 mm long; first glumes are up to half as long as the second, while the second is about as long as the slightly pubescent sterile lemma. The fertile lemma is glistening white, glabrous, and with margins only slightly inrolled over the palea.
- Comments: Few-flowered panic grass is similar to the other panic grasses but is not as hairy as P. lanuginosum and more purplish and with larger spikelets than in P. leibergii. According to the Lakota, this is toxic to horses.
Panicum virgatum (pan' nih come vir gay tum)
- Synonyms: None
- Common names: switch grass
- Origin and habitat: Native; open woods, prairies, and vegetated sand dunes
- Identifying characters: This perennial has tufted stems with very thick rhizomes and can reach heights of 1.5 m. Leaf blades are glabrous except near the collar where there are long hairs on the upper surface and shorter hairs on the margins. These hairs continue down the sheath margins a short way producing a V-shape appearance. Ligules are 1-3 mm long and very dense. Golden orange at maturity, the inflorescence is a very broad panicle, 2-4 dm long with purplish tear-drop shaped spikelets. The first glume is at least half as long as the second, while the second glume is about as long as the sterile lemma.
- Comments: Switch grass is subdominant and widely distributed in the tall-grass prairie. It generally occurs as scattered bunches. This is our tallest Panicum and easily identified by the dense collar hairs and the acuminate purplish spikelets. Switch grass provides good wildlife cover and can tolerate some grazing. Increasingly it is planted as an ornamental, providing upright form, golden autumn color (cv. 'Haense herms' has reddish color), and winter texture. It is an ideal accent plant, forming broad 4-6 foot bunches with long-lasting inflorescences. It does best on well-drained soils in full sun. Seeds require a period of dormancy(J.E. Weaver, 1968, Prairie plants and their environment, Univ. of Nebraska, Lincoln) before exhibiting rapid growth in spring.
Additional species in Minnesota:
Copyright 2002, A.F. Cholewa, J.F. Bell Museum of Natural History, University of Minnesota / No portion of this guide may be duplicated without written permission of author.