In the article on the floral aspects of British Guiana, cited above, the climatic and topographical features of the country are described. On the sandy savanna behind the East Coast Water Conservancy at the head of Horeabea Creek, Panicum mi<-ranthum was abundant. Guinea grass (Pwmeum maximum) is commonly grown in the drier regions of the tropics, but appears to be rare in Britain.
The open grassland near the coast consists mainly of three species: Bahama grass (Capriola dactylon, called Bermuda grass in the US); carpet grass (Axonopus compressv*) / :«nd sour grass (Paspalum conjugatnm). The order of genera is that of The Genera of Grasses of the United States, by A.
HORDE ATI
Culm very high, short-jointed, the sheaths conspicuously inconspicuous (the blades usually fall from the lower sheaths); staminate spikelets glabrous, the panicle is very different in appearance from that of the pistillate spikelets. 7. Clap with long joints, the sheaths not now Ombreker, the plants densely leafy at the base; staminate spikelets hairy, the plume resembles that of the pistillate spikelets 8.
CHLOBIDEAE
AGROSTIDEAE
OBYZEAE
ZIZANIBAE
PANICEAE
Spikelets solitary, subsessile, positioned so that the back of the fruit faces away from the rachis. Spikelets of 2 or 3 or singly, placed with the back of the fruit facing the crab. First deaf A missing (rarely present in spikelets, often present in P. decumbens); spikelets flattened, in dense one-sided panicle inflorescences.
ANDROPOGONEAE
Racemes 2, branching from the apex of a slender peduncle, a staminate spike without an axis resting on a fork.
TBXPSACEAE
Spikelets few to many flowers, compressed; husks and lemmas keeled, the lemmas 3-nerved; racbiUa often continuous, the paleas usually remaining persistent after the fall of the fruit. Palea-ciliates on the keels, the cilia usually as long as the width of the lemmas. Specimens from British Guiana: Lltchfleld, along railway line, Hitchcock 16826, Tumatumari, open sandy clay loam along road, Hitchcock 17333.
The numbers marked with an asterisk are in the Jenman Herbarium at Georgetown, but are not in the U, S. Spikelets articulate below the glume, 1-flowered with a prolongation of the rachilla or 2-flowered, the florets distant; glumes and lemmas acute.
ARTJNDO L
Specimens from British Guiana: Parika, low lying near the sea; plants no less than 8 meters high, Hitchcock 16759. Plant no less than 1 meter high, the lower leaves up to 50 cm. long with a canopy of about 8 mm. long, the hairs about 4 mm. long, elongated-linear, cleft at the apex. Originally described from southern Europe, this is commonly called Bahama grass in British Guiana and the British West Indies.
Specimens from British Guiana: Wismar, sand ridge in clean sand, Hitchcock 17273, Lake Ituribisci, Jenman 2246. Specimens from British Guiana: Georgetown, park behind sea wall, meadows among Bermuda grass, Hitohoock 16835.
ARISTIDA L
Pedicels erect, 0.6 to 1 meter high, in large clusters with numerous leafy shoots at the base; panicle 15 to 30 cm.
ORYZA L
FHARUS L
464 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. with one twist turning the upper and lower surfaces of the blade), the nerves run from the midrib to the edge. Spikelets with short stalks in large panicles; scales acuminate, tips widely spread, the second longer than the first and sterile foliage; fertile lemma minute, bearded on the callus bearing a long, slender axis from the apex,. Spikelets loosely arranged in several erect or ascending inflorescences, the second bract about as long as the spikelet, irregularly spinose and ventricose when mature.
Inflorescence of few to many races along a common axis; spikelets subsessile, solitary, the back of the fruit twisted from the slender racemes; Intemode of the rachilla between the first and second glume thickened, forming a ring-like base to the spike, the first glume usually reduced to an obscure sheath attached to the ring; fruit finely papillose-rugose, mueronate-pointed or with a delicate, often deciduous awn. Inflorescence of 2 to very slender racemes, joined at apex of tip; spikelets depressed-biconvex, oblong-elliptic, solitary, subsessive, the back of the fruit twisted from the rachis; first glume want; sterile palea obsolete. RANGE: Moist grassland, southern United States to Argentina; also in the warmer parts of the Old World.
This species is an important component of lowland grasslands in British Guiana and is an excellent forage grass.
PASF ALUM L,
Specimens from Bbitish Guiana : Penal Settlement, moist sandy soil, Hitch-cock 17065; open scrub land, Hitchcock 17245; rocks near river, Hitchcock 17246. An aquatic or submerged perennial, with submerged stems and floating branches raised from swollen sheaths, with thin, flat blades and panicles with many spreading racemes, spikes small, flat, elliptic, white in 2 rows on pale green rachls. AWAY: Wet land, Gulf States to Argentina; the tropics and subtropics of both hemispheres; throughout the West Indies; one of the most common grasses of moist savannas and canal banks, forming wide and narrow mats.
A low annual, branching profusely from the base and lower nodes, the sheaths and narrow linear blades hairy or almost glabrous; racemes a few at the top of the culm (rarely solitary), divergent, slender, about 3 cm. Specimens from Bbitish Guyana: Hills Estate, near Bartica, open moist soil in partial shade, Hitchcock 17195. Most leaflets are narrower than usual for the species, although occasional specimens of the species have leaflets that are equally narrow.
In all the racemes of the type specimen, the axes are longer and subacute, but the midrib is developed in less than a quarter of them and usually not in the entire raceme. Distribution: Savanna, open or partial shade, mostly moist soil, Mexico and West Indies to Brazil. A sandy, elevated area along the Mazaruni River below the penal settlement, a clearing in the forest affording a fine view of the river, was almost entirely occupied by this species.
The grass was cut and no fertile culms were seen except for a single specimen on the bank just below the main area. SPECIMEN from British Guiana: Penal Settlement, open ground on hillside by river, Hitchcock Within 30 miles of Georgetown," Rodway 32, the specimen in the City Museum of Georgetown. It is distinguished by its rhizomes, its elongated blades and by the small hairy mane of the keel on the crest of the sheath.
PANICUM L,
Culms erect, about 1 meter long, pubescent at the nodes; leaves raised, up to 1 cm. Range: A native of tropical Africa, commonly cultivated in the American tropics at low altitudes, often escaped and spontaneous* but rare in British Guiana. Specimens from British Guiana: Georgetown, Botanic Gardens, mud or shallow water along canal, Hitchcock 16528.
A slender branched, creeping perennial, the tops rising to a height of 20 to 30 cm, the short blades spreading or reflexed and usually pubescent; panicles small and open. Specimens from British Guiana: Lama Stop-off, in hummocks at base of larger plants, swamp, Hitchcock 16897.
CENCHRUS L
OLYBA L
The pistillate spikelets are much smaller than in any other species of the region. Wing, asymmetrically lanceolate-elongate, abruptly acute, usually 20 cm. long and 5 cm. wide, those of the last branches smaller, the lowest in both the primary apex and the rudimentary branches; panicle 10 to 15 cm. long, about two-thirds as long as wide, those of the secondary branches reduced, the branches strongly ascending or spreading, each bearing a large long-acuminate pistillate needle at the thick apex and several small slender-stalked staminate spikes along the rachis . Monoecious plants; staminate and pistillate spikes in small distinct panicles, staminate end or from Che upper nodes, pistillate axil; .. first glume of pistillate spikelets wanting, second glume and sterile lemma membranous, acuminate; fruit dorsally subcompressed, bony-lndurate.
Blades glabrous, firm, triangular-oblong, tapering from a truncate base to the rounded apex, 5 to 7 mm. broad at base 1. R. nana. An erect toned perennial with scaly rhizomes, the flat leaves mostly clustered towards the base, the slender, simple, almost naked crown 0.5 to 1 meter high, with a pale silky narrow plume. Range : Swamps and moist open ground, southern Mexico and the West Indies to northern South America.
It is a huge perennial with broad leaves, overlapping sheaths that fall from the short jointed lower part of the columns, large feathery brooms are pinkish silver.
ANDROIPOGON L
Series : Waste places; introduced in a few places in the West Indies from the tropics of the Old World, Originally described from Mauritius. A tall glabrous toned perennial with compressed stout culms, long linear blades and oblong panicles of small glabrous racemes partially enclosed in reddish-brown or purplish sops. A tall, robust, toned perennial, with long linear blades scabrous at the margin, and a large feathery corolla inflorescence of delicate racemes, one, sometimes two, of the upper pedunculate spikelets larger than the fertile ones, the other pdicedels spangles rudimentary.
Racemes 2, on slender stalks, covered with a spathe-like sheath, a staminate awnless spikelet borne at the top of the stalk in the fork of the two racemes, one or both racemes, sometimes again forked in the lower joints with a staminate spikelet in the fork, one of the secondary racemes reduced to a single joint. A robust, densely tufted, erect, branched perennial with scabrous-margined leaves, elongated pyramidal panicles and muricated splaylets. Distribution: Commonly cultivated in the American tropics as a hedge plant and for its aromatic roots, which are used for mats and screens.
HOLCUS L
A tall, branching annual with compressed culms, keeled sheaths, scabby leaves and solitary clusters of overlapping spikelets, the lower one being awnless. Ing a sharp callus under the spikelet; stamens spikelets subsessive, persistent on the slender, continuous raehis; racemes solitary or few to several, digitized.
MANISURIS L
ISCHAEMUM L
TRTPSACUM L
COIX L
This species is characterized by the large leaves, single or two approximately at the top of the sterile culms, and by the details of the inflorescence. Like other species of the genus, this one grows here and there, in the rich primeval forest, rarely more than one specimen in flower in one place.
