Rice Cutgrass is a warm season native perennial, semi-aquatic grass that flowers late, with the seed ripening in late August to early October.
Stems: The stems are upright to sprawling. If sprawling, the terminal part of the stem is always erect while the recumbant stem can root at the stem nodes.
Leaves: The yellow-green leaf blades are 3 to 12 inches long (7-30 cm) and up to 6/10 inch wide (6 to 15 mm). Leaves are coarse on top with tiny retorse teeth along the edges which can easily tear clothing and cut flesh, hence the common name "cutgrass". The leaf sheaths are also rough and can cut. Sheaths are open and can have sparse hair. The ligules are from 0.5 to 1.0 mm long.
Inflorescence: The flower head is a greenish to whitish terminal panicle, sometimes with axillary branches, that often droops and is from 10 to 30+ cm long (8 to 12+ inches). Branches are wiry. The panicle can have two or more branches from the lower nodes, usually only one from the upper nodes. Lower branches also divide. Sometimes the flowering branches do not emerge from the leaf sheaths, but produce seed within the sheath.
Flowering: The spikelets, which barely overlap, are referred to as 'naked' in that they do not have glumes. Spikelets are 4.0 to 6.5 mm long. These appear in clusters of 3 to 8 and not attached to the stem but toward the end of the panicle branches, with the lower 1/3 of the branch free of spikelets. The spikelets have only one floret and the florets have lemmas and paleas usually with a few straight hair on the keels and margins. Lemmas are 5-veined, most conspicuous on the margins. Anthers number 3.
Seed: The seeds do look like rice and thus are not easily confused with other grass seeds. Seed hulls are covered with minute bristles that cling to clothing or fur.
Habitat: Rice Cutgrass grows from scaly, elongate rhizomes which allow it to form dense colonies, which causes the plant to be called a weed if you are maintaining cranberry bogs. It is semi-aquatic, growing in swamps, wet meadows, muddy soils and marshy areas where it can receive plenty of sun. Rice Cutgrass is very valuable for wildlife. It provides habitat, seeds for food and ducks will pull up and eat the rhizomes.
Names: The genus, Leersia, is named for 18th Century German botanist Johann Daniel Leers. The species name, oryzoides is Greek for rice. As to the plant classification, the first to classify - 'L.' refers to Carl Linnaeus (1707-1778), Swedish botanist and the developer of the binomial nomenclature of modern taxonomy. His work was updated by ‘Sw.’ which refers to Olof Swartz (1760-1818) Swedish botanist who was a specialist in orchids, who had a botanical collection of 6000 specimens.
Comparisons: The other Leersia in the Garden, L. virginica, White Cutgrass, is differentiated by smooth leaf sheaths, solitary lower branches in the flowering head, smaller and more overlapping spikelets.
Above: The inflorescence. Note how the lower 1/3 of the panicle branches are free of spikelets and that the lower branches divide. Drawing 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.
Below: 1st photo - a panicle that is only partially emerged from the sheath. 2nd photo - the lower part of a large panicle.
Below: The clustered, slightly overlapping spikelets at the end of a panicle branch. Note the straight hair on the margins of the florets.
Below: 1st photo - more detail of individual florets. 2nd & 3rd photos - the leaf sheath is open with some sparse hair. Note the retorse stiff hair on the margins.
Below: 1st photo - stem nodes can have a cluster of hair. 2nd photo - the leaf blade has a prominent md-rib and stiff marginal hair.
Below: Mature seeds - note the minute bristles which catch onto clothing or fur.
Notes: Rice Cutgrass is indigenous to the Garden. Eloise Butler catalogued it in her early Garden records- she noted it in bloom on Aug. 14, 1912. The ability of this plant to withstand highly acidic conditions, has USDA studying it for use in constructed wetlands to mitigate agricultural runoff and also for treatment of acid mine drainage.
Rice Cutgrass is found throughout the United States and the lower Canadian Provinces. In Minnesota it is widespread, absent mainly in counties in the central part of the state.
Three species of Leersia are found in Minnesota - L. lenticularis, Catchfly Grass; L. oryzoides, Rice Cutgrass; and L. virginica, White Cutgrass. The first is very limited to 3 counties in the SE corner of the state and is on the Threatened List.
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.
Friends of the Wild Flower Garden, Inc. Text and photos are by G. D. Bebeau unless otherwise credited. "www.friendsofthewildflowergarden.org"