Chasmanthium laxum
An ornamental Southeastern U.S. native grass that thrives in moist sites from sun to shade, forms vigorous, well-separated clumps with long delicate seed heads, and supports wildlife while being useful for restoration, erosion control, and garden or green roof plantings.
Common Names
Slender Woodoats, Slender Chasmanthium, Slender Wood Oats
Summary
Slender Woodoats is a native North American perennial grass of the Poaceae, common in the southeastern United States. It grows in a loose, clumping habit with tall, unbranched culms about 40–130 cm tall and slender, glabrous leaves. The inflorescence is a contracted, erect panicle with branches that ascend to appressed; spikelets 4–9 mm long containing 2–5(7) florets with several lower sterile florets, and seed heads with arrowhead-shaped spikelets resembling oats.
Cultivation favours sunny to partially shaded sites with moist, well-drained soils; it tolerates a range of moisture conditions from moist to wet and exhibits moderate drought tolerance once established. Propagation is by spring sowing of seeds (germination in about 2–3 weeks) or by dividing established clumps in early spring or fall; it spreads slowly via rhizomes and reseeding to form colonies. Regular watering helps maintain moisture, while drip irrigation is recommended to avoid waterlogging; pruning in late winter or early spring promotes a bushier form. It attracts wildlife, serves in restoration and native plantings, erosion control, riparian and rain garden contexts, and may self-seed; potential pests include aphids, and diseases such as powdery mildew or rust can occur; deer, rabbits, and squirrels may browse, so deterrents or fencing may be needed.
Lifecycle
Perennial
Height
24-36 inches
Spread
12-18 inches
Hardiness Zones
Zones 6-9
Sunlight Requirements
Ideally full Sun to Full Shade; tolerates all four sunlight conditions.
Soil Type
Moist, well-drained loamy soil
Soil Drainage
No single ideal drainage specified; tolerates a wide range of moisture conditions, from dry-mesic to wetland.
Soil pH
6.0-7.0, slightly acidic to neutral
Bloom Color
Brown, Green
Bloom Time
Spring to Fall
Foliage Color
Green
Fall Foliage Color
Green
Leaf Lifecycle
Deciduous
Growth Rate
Moderate
Seasons of Interest
Spring, Summer, and Fall
Propagation Methods
Seeds, Division via rhizomes
Attracts Wildlife
Attracts butterflies, Attracts birds
Taxonomy
- Taxonomic Rank
- Species
- Author
- (L.) H.O.Yates
- Publication
- S. W. Naturalist 11: 433 (1966)
Superior Taxa
- Kingdom
- Plantae
- Subkingdom
- Pteridobiotina
- Phylum
- Angiosperms
- Order
- Poales
- Family
- Poaceae
- Genus
- Chasmanthium
Synonyms
Uniola uniflora Chasmanthium gracile Chasmanthium laxum subsp. sessiliflorum Holcus laxus Poa sessiliflora Uniola gracilis Uniola laxa Uniola longifolia Uniola sessiliflora Uniola virgata Chasmanthium laxum subsp. laxum Chasmanthium laxum var. laxum Chasmanthium laxum var. sessiliflorum Chasmanthium sessiliflorum