GEASS FAMILY. 27 



mostly 2-keeled, the inflexed margins enwrapping the flower. 

 Within and at the base of the hractlet are 2 (rarely 1, 3 or mote), 

 usually minute organs (the scales) which are sometimes considered as 

 representing additional rudimentary hraetlets, sometimes as the parts 

 of a rudimentary perianth; the scales at the time of anthesis become 

 turgid, pushing the bractlets and palea apart, thereby allowing the 

 anthers and stigmas to protrude; after anthesis they lose their turges- 

 cence, becoming hyaline, and allow the hractlet and palea to close 

 again. Perianth obsolete, unless represented by the scales. Stamens 

 usually 3, rarely 1, 2, 6 or more, nypogynous; filaments capillary; 

 anthers 2-celled, mostly versatile and pendulous at maturity, usually 

 proterandrous. Ovary superior, 1-celled. Styles usually 2, free, or 

 more or less united below, or obsolete; stigmas 2, widely branched and 

 usually plumose, covering a large area and thus specially arranged to 

 catch pollen carried by the wind, usually spirally branched, rarely 

 barbellate with papillate cells. Ovule 1. Fruit in ours an achene, 

 often adnate to the palea and sometimes also to the hractlet. Seed in 

 ours adnate to the pericarp. Embryo small, outside the base of the 

 endosperm. 



KET TO THE TRIBES. 



A. Spikelets 1-flovvered, the flower perfect; or with 1 perfect flower and 1 

 (rarely 2) empty braetLets or staminate flowers below (rarely above) it. Dice- 

 cious species and species with 2 or more perfect flowers sliould be looked for 

 under B. 



Both hractlet and palea cartilaginous, coriaceous or chartaceous (at least dis- 

 tinctly firmer In texture than the bracts) and becoming indurated in fruit. 

 Bachilla jointed below the bracts so that the spikelets fall from the pedicel 

 entire; spikelets terete, or flattened on the back only, not at all laterally 

 compressed; either strictly l-flowered or the perfect flower subtended by 1 

 (never more) empty hractlet or staminate flower; lower bract often Iierba- 



ceous and usually much the smaller 2. Panice^e, p. 29. 



Rachilla jointed above the bracts so that these remain after the flowers fall 

 away; spikelets laterally compressed on both sides; subtended by 2 

 (rarely only 1) sometimes minuie, empty bractlets or staminate flowers; 



bracts usually sub-equal 3. Phalabide.s:, p. 33. 



Only the hractlet flrmer in texture than the bracts and becoming indurated in 

 fruit; palea hyaline. 

 Awn terminal, geniculate; hractlet cylindrical-Involute:— Stipa in ... . 



4. AOROSTmEiE, p. 37. 



Awn dorsal, geniculate; hractlet not cylindrical-involute:— sometimes Avena 



in 5. AvEHEjE, p. 48. 



Neither hractlet nor palea firmer in texture than the bracts, though in Hordese 



both may be equally firm; often one or both of them hyaline. 



Spikelets pedicellate; arranged in lax or more or less dense and spikelike 



panicles or racemes; if in racemes or spikes these sometimes densely 



cylindrical hut the spikelets not in distinct rows. 



Spikelets of two kinds in the same inflorescence, one polygamous the others 



imperfect or rudimentary; two (one of each kind) or several at a node. 



Spikelets in pairs, or the terminal In tlirees, at each node of the jointed 



rachis, one (or two) pedicellate and (in ours) imperfect, the other 



sessile' and containing 1 perfect flower subtended by either a hyaline 



empty hractlet or a staminate flower. . . . 1. Andbopogone*, p. 28. 



Spikelets crowded at each node of a dense, 1-sided, brush-like panicle; the 



fertile solitary, short, terminating the panicle-branches and entirely 



concealed by the long sterile spikelets, which consist of about 10 



empty bractlets: — Lamarckia in 7. Festiice.e, p. 57. 



Spikelets ail of one kind in the same inflorescence, though their contained 

 flowers may be perfect, monoecious or polygamous. 



