INTRODUCTION. 



No introduction appears to be necessary further than 

 to give for the benefit of those unfamiliar with botanical 

 keys, an illustration of their use. For this purpose let 

 us supj30se that Ave have in hand a specimen of Orchard- 

 grass. After examining it carefully and noting the char- 

 acters presented by the inflorescence, spikelets, glumes, 

 etc., we turn to the key to the tribes on page 34, and 

 read the characters under " A. Spikelets one- rarely two- 

 flowered," etc. In our specimen the spikelets are 3-5- 

 flowered, so we pass to " B," on the next page. The 

 characters here — " spikelets 1-oc (many) flowered, . . . 

 rachilla articulated above the empty glumes, . . . with 

 distinct internodes between the flowers" (flowering 

 glumes) — are those of our plant, and we continue by 

 reading the characters following " a," all of which apply, 

 and then go on reading the characters following"**." 

 As those of our specimen are here included, the spike- 

 lets being upon distinct pedicels and disposed in a pani- 

 cle, we proceed to the next section of the key ; viz., 

 " I. Spikelets one-flowered." As those in our specimen 

 are 3-5-flowered, we pass on to " II. Spikelets 2-ao flow- 

 ered." Our Orchard-grass falls under this section, and 

 as it possesses characters (flowering glumes longer than 

 the empty ones, and with a short straight awn from the 

 point) which exclude it from the next division, "1," we 

 try " 2," which leads us to tribe XI, Festucese, further 

 described on page 135. Carefully comparing our plant 

 with the more extended characters here given, we note 

 their agreement (or disagreement, as would be the case 

 if we had proceeded wrongly to this point). 



Being satisfied that our plant must belong to the 



