Megathyrsus maximus*

Megathyrsus maximus* (Jacq.) B.K. Simon
& S.W.L. Jacobs. Austrobaileya 6(3): 572 (2003). Classification. (GPWG 2001) : Subfamily Panicoideae. Paniceae.

Basionym and/or
Replacement Name:
 Panicum maximum
Jacq., Icon. Pl. Rar. 1: 2, pl. 13 (1781).

Type of Basionym or
Protologue Information
: West Indies: Lesser Antilles: Leeward Islands, Guadeloupe, N. Jacquin s.n. (HT: W; IT: BM, P).

Recent synonyms:
Urochloa maxima.

Key references
(books and floras):
[1878] G.Bentham, Flora Australiensis 7 (484as Panicum
), [1952] C.A.Gardner, Flora of Western Australia 1 Gramineae
(260 as Panicum), [2002] D.Sharp & B.K.Simon, AusGrass, Grasses
of Australia
(as Panicum), [2006] J.Jessop, G.R.M.Dashorst,
F.M.James, Grasses of South Australia (463 as Panicum), [2008]
S.W.L.Jacobs, R.D.B.Walley & D.J.B.Wheeler, Grasses of New South Wales

[2006] J.Jessop, G.R.M.Dashorst, F.M.James, Grasses of South Australia  (463, fig. 396 as var. Panicum maximum var.
trichoglume), [2008] S.W.L.Jacobs, R.D.B.Whalley & D.J.B.Wheeler, Grasses
of New South Wales
, 4th edn (298).

Perennial or annual (rarely). Rhizomes absent or present, short. Stolons absent
or present. Culms erect or geniculately ascending, stature robust to moderate
or slender to delicate, (25–)75–200(–450) cm tall. Mid-culm internodes glabrous
or hispid or pilose. Mid-culm nodes glabrous or pubescent or bearded. Ligule a
fringed membrane, a ciliate membrane. Leaf-blades linear or lanceolate,
(6–)12–40(–100) cm long, (4–)10–35 mm wide. Leaf-blade surface glabrous or

Inflorescence compound, a panicle. Panicle oblong or pyramidal, 12–60 cm long.

Spikelets pedicelled. Fertile spikelets 2-flowered, the lower floret barren
(rarely male), the upper fertile, comprising 1 basal sterile florets,
comprising 1 fertile floret(s), without rachilla extension, oblong, dorsally
compressed, (2.5–)3–4.5(–5) mm long. Rhachilla internodes brief up to lowest
fertile floret.

Glumes dissimilar, thinner than fertile lemma. Lower glume ovate, membranous,
without keels, 1–3 -nerved. Lower glume surface glabrous or indumented. Upper
glume ovate, 2.1–3.5 mm long, membranous, without keels, 5 -nerved. Upper glume
surface glabrous or indumented. Upper glume apex muticous or mucronate. Florets.
Basal sterile florets 1, male or barren, with palea. Lemma of lower sterile
floret 100 % of length of spikelet, membranous, 5 -nerved.

Fertile lemma 1.9–5 mm
long, without keel. Lemma apex mucronate.

: Europe, Africa, Temperate Asia, Tropical Asia, Australasia,
Pacific, North America, and South America.

: Western Australia, Northern Territory, South Australia,
Queensland, New South Wales, Norfolk I.

: Drummond, Warren.
Northern Territory:
Darwin & Gulf. South Australia: Murray. Queensland:
Cook, Darling Downs, Leichhardt, Maranoa, Moreton, North Kennedy, Port Curtis,
South Kennedy, Warrego, Wide
Bay, Burke. New South Wales: North
Coast, Central Coast,
Northern Tablelands, North-Western Slopes, Central-Western Slopes,
North-Western Plains.

Introduced. Native to tropical Africa but now
widely introduced in the tropics and subtropics of the world. Flowers
essentially throughout the year.

Infra -specific
var. maximus, var. pubiglumis, var. coloratus, cv.
Embu, cv. Hamil.

1.Culms decumbent,
rooting at nodes                     M. maximus var. maximus cv. Embu           

 Culms tufted and erect, not rooting at nodes        2             

2. Spikelets indistinctly
hairy                                     M. maximus var. pubiglumis          

 Spikelets glabrous                                                       3             

3. Leaf hairy at
junction of sheath and blade       M. maximus var. coloratus             

 Leaf glabrous at junction of sheath and blade     4             

4. Plant 1.8–2 m tall;
leaf-blades 15–18 mm wide               M. maximus var. maximus             

 Plant 3–3.5 m tall; leaf-blades 24–26 mm wide   M. maximus var. maximus cv. Hamil   

AVH 2011   

AVH 2011    


Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith