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Chamaecrista rotundifolia (Pers.) Greene 1899
pronounced: kam-ay-KRISS-tuh roh-tun-dih-FOH-lee-uh
(Fabaceae – the pea family)
subfamily: Caesalpinioideae — the cassia subfamily
common name: Round-leafed Cassia
This native of Mexico, Central America, the Caribbean and South America was introduced into Australia as a pasture herb. It is a short-lived perennial or self-regenerating annual herb, sub-woody, prostrate or semi-erect, growing to 1 m tall, with a shallow taproot. The leaves are alternate, spiral, compound, bifoliate, stipulate, petiolate, the petiole 5–9 mm long; the leaflet blades are 20–25 or more mm long, 15–20 or more mm wide, asymmetrically ovate or obovate or orbicular, the base asymmetrically tapering or cordate or oblique (one side of the leaflet base tapering, the other cordate), the margins entire, the apex apiculate or obtuse or with a notched tip. The blade is hairy on the margins and below the leaf, with the upper surface mainly glabrous.
The flowers are found in axillary racemes, 1–3 flowered; they are predominantly yellow, somewhat irregular, pedicellate. The calyx has 5 sepals, joined, but almost free; the corolla has 5 petals, all petals free; there are 5 stamens, unequal and very short, free of the perianth, free of each other; the 1-celled ovary is superior.
This legume is sown into native pastures to augment the feed quality, and occasionally sown into pastures of improved grasses. It is only of limited value for hay because of substantial leaf-drop under dry conditions, leaving the woody indigestible stem. It has been successfully used in ‘haylage’† by combining it with Jarra digit grass (Digitaria milanjiana) before baling. It has been used in cut-and-carry systems in southern China, and as a ley legume in crop-livestock systems in Nigeria, where its use resulted in improved cereal production. The plant is very tolerant of heavy grazing, but, if it is allowed to grow tall and then cut low, individual plants fail to regenerate; but populations will regenerate from dropped seed.
Seed germinates quickly after rainfall. The seedlings grow rapidly, and early-flowering types can flower within 6 weeks. Round-leaf cassia appears to nodulate readily with native rhizobia.
It is generally not eaten readily by cattle in the growing season under high rainfall conditions, but becomes more accessible as the associated grasses mature later in the season. By late autumn it can comprise up to 20% of the diet. Horses usually won’t eat it.
† grass (often cut longer than for silage) partially dried and ensiled to exclude air, or plastic-wrapped in large bales
Photographs taken in Horseshoe Bay 2010, 2011
Page last updated 11th December 2017