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Paspalum conjugatum P.J.Bergius

Common name
Sour Grass
Hilo Grass
Johnson River Grass
Yellow Grass

Paspalum L., Syst. Nat. 10th edn, 855 (1759); from the Greek paspalos (a kind of millet).

conjugatum- from the Latin conjugo (yoke together). Inflorescence branches paired.

Published in
Acta Helv. Phys.-Math .7: 129 (1762).

Perennial. Cataphylls present. Stolons present, with alternating elongated and bunched internodes. Culms erect, 20–100 cm tall, 3–10-noded. Mid-culm nodes glabrous. Lateral branches sparsely branched. Leaf-sheaths outer margin glabrous. Leaf-sheath auricles absent. Ligule an eciliate membrane, 0.3–1.5 mm long. Leaf-blades linear or lanceolate, 4–20 cm long, 5–15 mm wide. Leaf-blade surface smooth, glabrous or hairy.

Inflorescence digitate, a panicle of racemes. Racemes 2–3, spreading, unilateral, 4–17 cm long, 0.8–1 mm wide, bearing 120–250 fertile spikelets on each. Rhachis wingless or narrowly winged or broadly winged, angular, 0.5 mm wide. Spikelet packing abaxial, regular, 2-rowed.

Spikelets solitary. Pedicels 0.15–0.3 mm long. Fertile spikelets 2-flowered, comprising 1 fertile floret, lower floret sterile, upper fertile, without rhachilla extension, orbicular, dorsally compressed, plano-convex, obtuse, 1.2–1.8 mm long, falling entire.

Glume 1 (the lower absent or obscure), thinner than fertile lemma. Upper glume orbicular, 1.2–1.8 mm long, 100% of length of spikelet, hyaline or membranous, yellow, 2–3-nerved. Upper glume surface glabrous. Upper glume margins ciliate. Upper glume apex obtuse.

Basal sterile floret 1, without significant palea. Lemma of lower sterile floret similar to upper glume, elliptic, 1.2–1.8 mm long, 100% of length of spikelet, membranous, 2-nerved, obtuse. Fertile lemma orbicular, gibbous, 1.2–1.8 mm long, indurate, pallid or yellow, 3-nerved. Lemma surface striate. Lemma margins involute. Lemma apex acute. Palea involute, cartilaginous or indurate. Anthers 0.4–0.5 mm long.

Continental Distribution:
Africa, Temperate Asia, Tropical Asia, Australasia, Pacific, North America, South America.

Australian Distribution:
Western Australia, Northern Territory, Queensland, New South Wales.

Western Australia: Gardner. Northern Territory: Darwin & Gulf. Queensland: Cook, North Kennedy, South Kennedy, Port Curtis, Wide Bay, Moreton. New South Wales: North Coast.

Classification. (GPWG 2001):
Panicoideae: Paniceae

Introduced. In tropical heaths, tropical and subtropical rain forests, and temperate rain forests. Preferring wet roadsides or ditches and quickly spreading via highly productive stolons. Flowers Apr.–Aug.

Illustrations available:
Inflorescence (photo)
Detail of inflorescence (line drawing)
Australian distribution

Inflorescence (photo)
© Queensland Herbarium
Sharp 290 and Simon
by D.Sharp

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Detail of inflorescence (line drawing)
© Queensland Herbarium

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Australian Distribution

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