Plant: A short-lived, summer growing perennial legume (in wetter environments) or a self-regenerating annual (in drier, frosty environments); herbaceous to slightly woody; prostrate to semi-erect, growing to 1m tall, with a shallow taproot.
Stems: Stems slightly hairy, 45-110 cm long.
Leaves: Rounded with two leaflets.
Flowers: Up to three small yellow flowers originating from the leaf axils.
Pods: Flat, straight or slightly curved, up to 6cm long, shattering when mature
Seeds: Seeds small, rectangular, flattened, sometimes pointed on the corners, tan to light brown, 2-3 mm long; 200,000-470,000 seeds/kg.
Sown into native pastures to improve feed quality and as a legume component of long term sown grass pastures; colonises readily.
Grows as a perennial in a 900-1,500 mm rainfall region, and as an annual in a 550-900 mm region.
Free-draining light soils of acid to neutral pH, particularly sands or sandy loams of low to moderate fertility.
Summer growing, top growth killed by frost. Where regular heavy frosts occur, round-leaf cassia behaves as an annual.
Grasses: Indian blue grass, Rhodes grass, Digit grass, Tall finger grass, and any other grasses adapted to lighter soils.
Legumes: Fine stem stylo, Lotononis, joint vetch, serradella, biserrula.
Sowing/planting rates as single species
1 kg/ha bare seed and 3 kg/ha + coated seed, depending on seed coat weight.
Sowing/planting rates in mixtures
0.5 kg/ha bare seed and 1.5 kg + coated seed, depending on seed coat weight.
Group M; promiscuous but inoculation is recommended.
Responds to phosphorus and sulphur on soils of low-fertility (based on soil test).
Phosphorus and sulphur on soils of low-fertility.
Very tolerant of and requires constant heavy grazing, If allowed to grow tall and then ‘crash’ grazed, individual plants fail to regenerate and die. Populations will regenerate from seed. Not selectively grazed in the young, growing stages but preferred when the leaves are older, often after seed set.
Ability to spread
Will spread naturally through seed shattering and in dung after ingestion by livestock.
Large seed set and low seasonal palatability suggest this plant could have weed potential though this is unlikely and has not been observed in drier environments.
Not known; generally not sown in areas where herbicides are used.
Good protein and digestibility levels recorded under grazing on fertile soils. Application of P and S on low fertility soils in southern Queensland increased N concentrations of leaf tips to 3.3% N (21% crude protein). ‘Wynn’ cassia has raised the N concentration of black speargrass by 20-40% under grazing and fertilising (with P & S).
Generally not readily eaten by cattle in the growing season under higher rainfall conditions, but becomes more acceptable as the associated grasses mature later in the season. Can comprise up to 20% of the diet in late autumn. Lower seasonal palatability differential in drier areas as plant tissue is generally drier. Not eaten by horses.
DM yields of up to 7,000 kg/ha recorded in south-east Queensland but less in drier environments.
No known anti-nutritional factors.