Paspalum mandiocanum Trin., Poaceae

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Present on Pacific Islands?  no

Primarily a threat at high elevations?  no

Risk assessment results:  Risk assessment from the Government of Queensland, Australia (PDF format).

Common name(s): [more details]

English: broad-leafed paspalum

Habit:  grass

Description:  "Perennial; caespitose. Culms decumbent; 45-125 cm long; without nodal roots, or rooting from lower nodes. Culm-internodes distally glabrous. Leaf-sheaths keeled. Ligule an eciliate membrane. Leaf-blade base broadly rounded. Leaf-blades lanceolate; 10-30 cm long; 8-17 mm wide. Leaf-blade surface glabrous. Leaf-blade margins ciliate. Leaf-blade apex acute.  Inflorescence composed of racemes. Racemes 4-6; borne along a central axis; unilateral; 3-9 cm long. Rhachis angular; 1 mm wide. Spikelet packing 4 -rowed. Spikelets in pairs. Fertile spikelets pedicelled. Pedicels oblong. Fertile spikelets: Spikelets comprising 1 basal sterile florets; 1 fertile florets; without rhachilla extension. Spikelets elliptic; dorsally compressed; plano-convex; 2-2.1 mm long; 1.5 mm wide; falling entire. Glumes one the lower absent or obscure; reaching apex of florets; thinner than fertile lemma. Upper glume elliptic; 1 length of spikelet; membranous; without keels; 5 -veined. Upper glume apex acute. Florets: Basal sterile florets barren; without significant palea. Lemma of lower sterile floret elliptic; 1 length of spikelet; membranous; 5 -veined; acute. Fertile lemma elliptic; 2-2.1 mm long; indurate; pallid; without keel. Lemma margins involute. Palea involute; indurate. Flower: Anthers 3. Fruit: Caryopsis with adherent pericarp"  (Clayton et al., 2002).

Habitat/ecology:  "Broad-leafed paspalum is an unpalatable, introduced grass which invades cattle and horse pastures by out-competing and replacing palatable native pasture species. It can out-compete the native pasture grasses because it is a hardy, adaptable plant. It tolerates both dense shade and drought conditions, grows quickly (particularly after rainfall), smothers less competitive grasses by spreading horizontally, produces a large number of seeds and has a high rate of germination.  Plants grow in open pasture, along roadside verges, in bush margins but also in deeply-shaded sections of forest"  (Queensland Government, 2008).

Propagation:  Seed

Native range:  Southern Brazil; Argentina, Paraguay and Uruguay (GRIN).

Presence:

Pacific Rim
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
Australia Australia (continental)	Queensland	introduced invasive	Queensland [Australia] Government (2008)

Control: 

Physical:  "Seedlings and smaller plants can be hand-pulled, bagged and composted or disposed of at the local garbage dump. Wear gloves, as the leaves and seed heads can cause skin irritation."

Chemical:  "Chemical control, such as foliar spray, may be required for larger infestations of broad-leafed paspalum. In this case, we recommend using a glyphosate 360 g/L herbicide (e.g. Weedmaster Duo®) at a rate of 10 ml per 1 L of water. Take care however, as the herbicides will damage other plants (not broad-leafed paspalum) if they are accidentally sprayed. Spray in spring when the plants are actively growing"  (Queensland Government, 2008).

Additional information:
Fact sheet from the Government of Queensland, Australia (PDF format).

Additional online information about Paspalum mandiocanum is available from the Hawaiian Ecosystems at Risk project (HEAR).

Information about Paspalum mandiocanum as a weed (worldwide references) may be available from the Global Compendium of Weeds (GCW).

Taxonomic information about Paspalum mandiocanum may be available from the Germplasm Resources Information Network (GRIN).

References:

Clayton, W.D./Harman, K.T./Williamson, H. 2011. World Grass Species: Descriptions, Identification, and Information Retrieval [GrassBase - The Online World Grass Flora]. The Board of Trustees, Royal Botanic Gardens, Kew.

Queensland [Australia] Government. 2008. Broad-leafed Paspalum. Department of Primary Industries and Fisheries, Land Protection (Invasive Plants and Animals). PP 145. 2 pp.

U.S. Dept. Agr., Agr. Res. Serv. 2011. National Genetic Resources Program. Germplasm Resources Information Network (GRIN). Online searchable database.