POACEAE 27 



Key to the Tribes. 



Spikelets or clusters of spikelets in two rows in spikes; sessile. 

 Spikelets in two approximate rows, forming a one-sided spike. 

 Flowering scales not hardened; empty scales keeled. 



3. Chlorideae. 

 Flowering scales hardened; spikelets flattened dorsally; empty 

 scales not keeled. 6. Paniceae. 



Spikelets in two opposite rows. 2. Hordeae. 



Spikelets not in two rows; pediceled in panicles, spike-like panicles 

 or racemes. 

 Spikelets 2 to many flowered; the lowest flower always perfect. 

 Flowering scales generally longer than the empty scales; awn- 

 less or straight awned at or near the apex. 1. Festuceae. 

 Flowering scales shorter than the empty scales, usually with a 

 bent dorsal awn. 4. Aveneae. 



Spikelets 1 or 2 flowered, when 2-flowered the lower staminate or 

 rudimentary. 

 Palet keeled, similar to the flowering scale; empty scales small 

 or wanting. 8. Oryzeae. 



Palet quite different from the flowering scale, empty scales usually 

 present. 

 Flowers, at least some of them, perfect. 

 Spikelets alike, all with a perfect flower. 



5th scale enclosing the flower, 3rd and 4th small, aften 

 reduced to bristles. 5. Phalarideae. 



3rd or 4th scale enclosing the flower. 



Flowering scales if indurated awned, the 3rd scale en- 

 closing the flower. 7. Agrostideae. 

 Flowering scales indurated, awnless; the 4th scale usual- 

 ly enclosing the flower. 6. Paniceae. 

 Spikelets of two kinds, some perfect, and sessile, accom- 

 panied by 1 or 2 pediceled, staminate or rudimentary ones. 



9. Andropogoneae. 



Flowers all staminate or pistillate; the staminate above the 



pistillate. 10. Maydeae. 



Tribe 1. Festuceae. 



Styles short with plumose stigmas protruding at the sides of the 

 scales; inflorescense various, not of axillary clusters. 

 Rachilla, if hairy, with hair much shorter than the flowering scales. 

 Flowering scales 5-many nerved. 

 Upper scales, if empty, narrow and not enclosing each other. 

 Flowers perfect. 



Spikelets not in dense one-sided clusters. 



Styles attached below the apex of the ovary; flowering 

 scales usually over 6 mm. long. 1. Bromus. 



Styles attached to the tip of the ovary; flowering scales 

 6 mm. long or lessr 

 Flowering scales rounded on the back. 



Flowering scales without hairs at the base. 



