2076 A TEXTBOOK OF THEORETICAL BOTANY 



as a cereal in Ceylon, India and Africa under the name of Ragi or Kurakkan. 

 Other species are used for fod'der. ; 



6. Chlorideae. Annual or perennial herbs with narrow leaf blades. 



Spikelets usually laterally compressed, one- or few-flowered, 

 with one hermaphrodite flower with or without imperfect florets 

 above and below it. Spikelets borne in one or two rows on one 

 side of a continuous rachis or solitary or scattered, forming spikes 

 or racemes. Glumes usually persistent. Outer paleae mem- 

 branous, entire or emarginate or two or three-lobed, awnless 

 or awned, one- to three-nerved with lateral nerves near the 

 margins and often ciliate. Lodicules two, rarely suppressed. 

 Stamens usually three. Fruit a caryopsis enclosed in the inner 

 and outer paleae. 



This tribe includes about thirty-five genera mostly inhabiting tropical 

 regions, though some extend into the warm, or even into cool temperate 

 regions. One of the best-known genera is Spartina. There are about half a 

 dozen species. S. stricta occurs in salt marshes in Britain, while the fully 

 fertile hybrid, S. tozvnsendii, of this species with the North American S. 

 alterniflura has become an invader and stabilizer of maritime mud flats in 

 southern and western estuaries round Great Britain in recent years. The 

 genus Cynodon is represented in Britain by C. dactylon which is restricted to 

 sandy parts of the south coast. It is common in all warm countries. Other 

 important genera in this tribe are Chloris, Boiiteloua, Cteniiim and Trichloris. 

 A number of the genera are valuable fodder grasses, while species of 

 Cynodon are used as lawn grasses. 



7. Nardeae. Densely tufted perennials with siliceous leaf bases. 



Spikelets (Fig. 2012) hermaphrodite and one-flowered, alternate 

 in notches along one side of the continuous rachides of the 

 solitary terminal spikes. Glumes suppressed. Outer paleae 

 acuminate or awned from the tip, three-nerved. Lodicules sup- 

 pressed. Stamens three, style solitary with a papillose stigma. 

 Fruit a caryopsis, lying free between inner and outer paleae. 

 There is only a single genus, Nardus, with one species, N. stricta, which 

 is widely distributed in Europe, northern Asia and in Greenland and New- 

 foundland. It is found in Britain as the commonest grass of drier grass 

 moors. Although separated by Hubbard in a distinct tribe, the genus 

 Lygeiim is included here by Arber. There is only one species, L. spartum, 

 which occurs in the Mediterranean region and is one of the Esparto grasses. 



8. Aveneae. Annual or perennial herbs with narrow leaf blades. Spike- 



lets (Fig. 2013) all alike, one- to seven flowered, with all florets 

 hermaphrodite or only the upper ones barren. The spikelets 

 arranged in open or contracted panicles. Glumes persistent, 

 usually as long as the lowest outer paleae and often as long as the 

 spikelets, membranous with shining margins. Outer paleae 

 with membranous margins, often hyaline and usually five- 



