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Chasmanthium sessiliflorum

North American native perennial in the Poaceae with sessile leaves, forming about 3-foot-tall clumps with V-shaped spikelets on long panicles that bloom July–October, tolerating moist soils, and commonly used as groundcover or a border plant in the southeastern United States.

Common Names

Longleaf Woodoats

Summary

Longleaf Woodoats, Chasmanthium sessiliflorum, is a native North American perennial grass in the Poaceae family that forms clumps about 0.9–1.0 m tall and wide. Leaves are basal and arranged in two ranks, with flat blades and a drooping habit; the inflorescence is a panicle about 2 ft long with flat, V-shaped spikelets, and flowers are green with brown fruits; the plant is winter-dormant. Native to Virginia and the Southeastern United States, including Florida and Georgia.

Cultivation favors part shade and moist soils with occasional inundation, tolerating clay, loam, and sand with neutral to slightly acidic pH. Propagation is possible from plugs or seed, with establishment slow. In landscape use, it serves as a border plant and for restoration, providing wildlife value as seeds are consumed by birds and other animals. It has low tolerance for long-term saltwater flooding and moderate tolerance to salt spray.

Lifecycle

Perennial

Height

36 inches

Spread

3 feet

Hardiness Zones

Zones 8a-10a

Sunlight Requirements

Ideally partial shade.

Soil Type

Moist to wet moderately well-drained soils with humus, neutral to slightly acidic clay/loam/sandy soils, calcareous shell-rich soils

Soil Drainage

Moist, well-drained soils.

Soil pH

6.5-7.0

Neutral to slightly acidic

Bloom Color

Brown (including maroon), Green, Greenish white

Bloom Time

Summer

Leaf Lifecycle

Deciduous

Growth Rate

Slow to establish

Seasons of Interest

Summer

Propagation Methods

Plugs and seed

Attracts Wildlife

Attracts birds

Taxonomy

Taxonomic Rank
Species
Author
(Poir.) Yates
Publication
S. W. Naturalist 11: 426 (1966)
Synonym Of
Chasmanthium laxum

References

Florida Native Plant Society (FNPS). fnps.org.
How to care for Northern sea oats - Complete Plant…. plantsnap.com.
IRC - Natives for Your Neighborhood. regionalconservation.org.
Chasmanthium sessiliflorum - Species Page. tennessee-kentucky.plantatlas.usf.edu.
Digital Atlas of the Virginia Flora | Chasmanthium…. vaplantatlas.org.
Longleaf Wood Oats (Chasmanthium sessiliflorum). cottagegardennatives.com.
Chasmanthium sessiliflorum (TVA, White's Creek…. inaturalist.org.
World Flora Online. worldfloraonline.org. June 2024.