104 POACEAE 



styles, and usually plumose stigmas ; fruit a caryopsis with starchy endosperm and 

 a small embryo at the base on the side opposite the hilum. The perianth is usually 

 represented by 2 small hyaline scales (the lodicules ) at the base of the flower 

 inside the lemma and palea. The lemma, palea. and inclosed flower constitute the 

 floret. The spikelets are almost always aggregate in an inflorescence at the ends 

 of the main culms or branches. The grain or caryopsis (the single seed and the 

 adherent pericarp) may be free, as in wheat, or permanently inclosed in the 

 lemma and palea, as in the oat. Rarely the seed is free from the pericarp, as in 

 species of Sporoholiis and Elcusine. The culms are solid in our species of Andro- 

 pogoncac. The margins of the sheaths are grown together in species of Brouuis, 

 Fcstiica, Mclica, Panic iilaria, and others. The parts of the spikelet may be modi- 

 fied in various ways. The first, and more rarely also the second, glume may be 

 wanting. The lemmas may contain no flower, or even no palea, or may be reduced 

 or rudimentary. The palea is rarely wanting in perfect florets (species of 

 Agrosf'is). 



A large family of about 500 genera distributed throughout the world, in all latitudes and altitudes 

 where are found conditions suitable for plant growth, but least abundant in dense tropical forests. 



A. Spikelets with 1 perfect terminal floret (disregarding the staminate and neuter spikelets) and (except 



in Hilaria) a sterile or staminate floret below, usually represented by a sterile lemma only, one glume 

 sometimes wanting: articulation below the spikelets, either in the pedicel, in the rachis, or at the base 

 of a cluster of spikelets, the spikelets falling entire, either singly, in groups, or together with joints 

 of the rachis; spikelets, or at least the fruits, more or less dorsally compressed (except in Hilaria). 



Subfamily Panicatae. 

 Glumes indurate; fertile lemma and palea hyaline or membranaceous, the sterile lemma (when present) 

 like the fertile one in texture. 

 Spikelets in pairs, one sessile, the other pedicellate (the pedicellate one sometimes obsolete, rarely 

 both pedicellate) ; lemmas hyaline. I. Andropogoxeae. 



Spikelets in groups of 2-5, the groups falling entire from the continuous axis. II. Nazie.\e. 



Glumes membranaceous; fertile lennna and palea indurate or at least firmer than the glumes; sterile 

 lemma like the glumes in texture. III. Pamceae. 



B. Spikelets 1 to many-flowered, the reduced florets, if any, above the perfect florets (except in Phalari- 



deae) ; articulation usually above the glumes, spikelets usually more or less laterally compressed. 



Subfamily Po.\tae. 

 Spikelets with 2 staminate, sterile or rudimentary lemmas unlike and below the fertile lemma: no sterile 

 or rudimentary florets above. \". Phalarideae. 



Spikelets without sterile lemmas below the perfect floret. 



Spikelets articulate below the glumes, 1-flowered, very flat, the lemma and palea about equal, both 

 keeled, the glumes small or wanting. I\ . Orvze.\e. 



Spikelets usually articulate above the glumes. 



Spikelets sessile on a usually continuous rachis (short-pedicellate in Lcptociiloa ; the rachis dis- 

 articulating in Sitanion and in a few species of allied genera). 

 Spikelets on opposite sides of the rachis; spike terminal, single. X. Hordeae. 



Spikelets on one side of the rachis; spikes usually more than 1, digitate or racemose. 



\'III. Chlorideae. 



Spikelets pedicellate in open or contracted (sometimes spike-like) panicles. 



Spikelets 1-flowered. \'l. Agrostideae 



Spikelets 2 to many-flowered. 



Glumes as long as the lowest floret, usually as long as the spikelet; lemmas awned from the 

 back (spikelets awnless in Kocleria, Sphenofholis and Trisctum wolf it). 



\'II. Aveneae. 



Glumes shorter than the first floret (except in Dissantheliinn) ; lemmas awnless or awned 

 from the tip (from a bifid apex in Bromus and Triodia). IX. Festuceae. 



Tribe I. Andropogonea'e. 



Spikelets all fertile, surrounded by copious soft hairs; inflorescence a narrow panicle 



1. Imperata. 

 Spikelets unlike, the sessile perfect, the pedicellate staminate or neuter. 



Racemes of several joints, silky-villous. 2. Andropogoii. 



Racemes reduced to 1 or few joints, these in a compound panicle, not silky-villous. 



3. Holcus. 



Tribe IL Nazieae. 



A single genus. 4. Hilaria. 



Tribe III. Paniceae. 



Spikelets subtended or surrounded by 1 to many bristles (sterile branchlets). these distinct or connate. 



Bristles slender, separate, persistent, the spikelets deciduous. 10. Chactochloa. 

 Bristles united or connate, forming a bur with retrorsely barbed spines, the bur falling with the 



spikelets. 11. Ceuchrus. 

 Spikelets not subtended by bristles. 



Glumes awned or mucronate; apex of palea not inclosed by the lemma. 9. Echinochloa. 

 Glumes awnless; apex of palea inclosed by the lemma. 



Spikelets in panicles. 8. Panicitm. 

 Si)ikelets in 1-sided spikelike racemes. 



First glume and the rachilla joint forming a 'swollen ringlike callus below the spikelet; 



racemes several along the main axis. 6. Eriochloa. 



First glume present or wanting, not forming a ringlike callus; racemes aggregate at the 

 summit of the culm. 



Racemes slender, 3-12. 5. Syntherisma. 



Racemes stout, in pairs. 7. Paspalum. 



