River Oats is a native, clump-forming, upright grass in the Poaceae (grass) family. This easy to grow ornamental grass reaches a height between 2 to 5 feet and width of 1 to 2 feet. The distinctive flat nodding seed heads that resemble oats emerge green in spring, turn tan in summer and then purplish in fall. They sway gracefully in the slightest breeze. The bamboo-like leaves often turn yellow-gold in fall if given enough sun. This plant is a larval host plant for butterflies as well as a food source for small mammals and birds. It is easily grown in moist to wet well-drained soils in part sun to part shade. It is fairly tolerant of shade, especially for an ornamental grass. Use in naturalized areas, along streams or edges of water gardens. Watch its placement especially in smaller gardens as may spread aggressively by rhizomes and seeds. This plant was selected as the 1994 NC Wildflower of the Year , a program managed by the North Carolina Botanical Garden with some financial support from the Garden Club of North Carolina. Insects, Diseases, and Other Plant Problems: It can be a bit weedy as it self seeds easily.
Curated pairwise relationships between this plant and others in the library — who feeds
whom, who competes, who confuses the pests. Green reads as a good pairing, red as one to avoid.
No curated interactions recorded for this species yet.
Also noted by NC State
Related species the NC State Plant Toolbox flags for this plant — look-alikes to tell
apart, and plants that play a similar role in a planting. Ones we carry in the library are linked.
Dappled Sunlight (Shade through upper canopy all day) | Partial Shade (Direct sunlight only part of the day, 2-6 hours)
Soil texture
Clay; Loam (Silt); Sand
Soil drainage
Moist | Occasionally Wet
Available space
12 inches-3 feet
NC region
Coastal; Mountains; Piedmont
Mature size
Height: 2 ft. 0 in. - 5 ft. 0 in. | Width: 1 ft. 0 in. - 2 ft. 6 in.
Growth rate
Medium
Maintenance
Medium
Canopy layer
4 - Herbaceous (3-15 ft)
Form & Appearance
Habit / form
Clumping; Erect
Texture
Coarse
Foliage
Deciduous
Leaf color
Green
Leaf type
Simple
Leaf arrangement
Alternate
Leaf shape
Lanceolate; Linear
Leaf margin
Entire
Leaf value
Long-lasting; Showy
Leaf size
> 6 inches long, < 1 inch wide
Hairs present
No
Leaf detail
5-9 inch long and 1-inch wide flat green leaf blades are upright to slightly arching, turn a yellow-coppery color in fall and brown in winter.
Fall color
Brown/Copper; Gold/Yellow
Flower color
Brown/Copper; Green; Purple/Lavender
Flower value
Good Dried; Long-lasting; Showy
Flower form
Panicle; Spike
Flower size
1-3 inches
Flower detail
The inflorescence is an open panicle with branches nodding or drooping. It is initially green, turning brown at maturity. The individual spikelets are up to 1-1/2 inches long and over 1/2 inch wide, with typically 6 to 17 florets. Flowers bloom from June to October and are wind pollinated.
Seed heads are green to tan then purplish bronze from July to November.
Stem color
Green
Stem detail
Green and smooth
Wildlife & Ecology
Native status
Native
Origin
Central Canada, Central & E. U.S.A. to NE. Mexico
Distribution
AL , AR , AZ , DC , DE , FL , GA , IA , IL , IN , KS , KY , LA , MD , MI , MO , MS , NC , NJ , NM , OH , OK , PA , SC , TN , TX , VA , WI , WV
Wildlife value
This is a larval host plant for Northern Pearly-Eye (Lethe anthedon) caterpillars. You may see two broods from May-September in the south or one brood from June-August in the north. Highly resistant to deer. Also a larval host plant to several skipper butterflies. Small mammals and birds are attracted to the seeds.
Attracts
Butterflies; Pollinators; Small Mammals; Songbirds