GROUP V. ANGIOSPERM^ : MONOOOTYLEDONES. 489 



The stem is generally characterised by swollen or tumid nodes, 

 to which the sheathing leaf -bases contribute. The long internodes 

 are hollow : the sheathing leaf-bases are largely developed, and 

 frequently extend over several internodes. A membranous ligule 

 is developed at the junction of leaf-base and lamina (see p. 32 ; 

 Fig. 19 A). 



The more common Grasses are classified as follows : 



Series A. PAXICOIDE^ : spikelet one-flowered, or sometimes two-fiowered 

 and then the lower flower is imperfect; articulated so that it falls off 

 entire after flowering ; no prolongation of the axis beyond the flower. 



Tribe 1. Panicece : spikelets dorsally compressed, in compound spikes : 

 glumes 3, of which the lowest is the smallest : inferior palea without an 

 awn. 



Panicum fflabrum (Digitaria humifusa), P. (Echinochloa) Crus-gaUi, and P. 

 (Setaria) viride occur occasionally on cultivated land. P. miliaceum yields 

 Millet (Fig. 300). 



Tribe 2. Maydece: the diclinous flowers are in distinct spikelets; the 

 two kinds of spikelets usually form distinct inflorescences, but sometimes 

 they occur in different parts of the same inflorescence : the lowest glume is 

 the largest. 



Zea Mais, the Maize Plant, cultivated in warm countries, is a native of 

 Tropical America: the $ spikelets form a loose panicle at the apex of the 

 haulm, and the ? flowers are borne laterally on a thick spadix, which is 

 ensheathed by leaves. 



Tribe 3. Andropogonece : flowers monoecious or polygamous : glumes 3, of 

 which the lowest is the largest. 



Saccharum Officinarum, the Sugar-cane, is a, native of the East Indies. 

 Andropoyon Sorghum, in different varieties (vulgaris. Durra, etc.), yields a 

 kind of Millet seed : the flour of this is known in Arabia and India as 

 Durra. 



Tribe 4. Oryzece : spikes laterally compressed : glumes 2-4, often repre- 

 sented only by bristles : stamens generally 6. Oryza saliva is the Rice- 

 plant, from the East Indies; cultivated in marshy regions of Southern 

 Europe. Leemia oryzoides, the Cut-grass, is found in ditches in the South 

 of England. 



Series B. POOIDE^: : spikelet one- or many-flowered, with distinct inter- 

 nodes between the flowers : when one-flowered, the axis of the spikelet is 

 prolonged beyond the flower : the' ripe fruits fall, leaving the glumes 

 behind. 



Tribe 5. Phalaridece: spikelets pedicillate in panicles, laterally com- 

 pressed, 1-flowered : glumes 4, the inner pair being smaller. Phalaris 

 arundinacea, the Reed-Grass, is common on the banks of streams, etc. : 

 a variety with white-streaked leaves is cultivated in gardens. Anthox- 

 anfhum odoratum, Vernal-Grass, which has only two stamens and a pani- 

 culate inflorescence, is common in meadows : it gives the peculiar odour to 

 fresh hay.' 



