XIV 



INTRODUCTION. 



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■ Sheath-scales, or stipules, fsf'P^^^J^ «f S^^^'^'^ ^^^ '"'^^ membranaceous substances at. 

 tached to the inner sides of the leaves; they have their origin at the top of the vagina, or the 

 point where the leaf first diverges from the straw. Its varieties are : 



1. Intire, CmtegraJ, when it has no segments. 



9. Bifid, (bifida), when it is divided at the apex into two parts. 



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3. Torn, (lacera), when it appears as-if torn on the margin. 



4. Fringed, (ciliata), when the margin is set with short projecting hairs. 



5. Truncated, (trimcata), when the upper part terminates in a transverse Ime. 



6. Pointed, (acuta), that has a short acute point. 



7. Accuminated, (acciiminata), that has a long projecting point. 



8. Very short, (decurrens), that is hardly visible, and runs down the side of the vagina. 



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The stipules often afford a good character of distinction. I have raised a great many species 

 of different grasses from seed, under different circumstances, as to soil and situation, with a 

 view to obtain varieties from them. I found many of the plants thus raised, to vary from the 

 parent, in the number of the flowerets, in the presence or want of hairs on the surface, and 

 sometimes, though rarely, in the awns; but in no instance did the form of the stipula or sheath- 

 scale vary : being thus constant, it may be depended on. . 



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IV. 



Varieties of the Flower. 



The curious structure of the flowers of grasses, and a consideration of their important office, 

 that of forming the seed, is sufficient to attract notice or regard, independent of the great use, 

 of which a knowledge of their structure is, in distinguishing with certainty the several species 

 and varieties. 



Inflorescence, or the manner in which the flowers of grasses are supported and disposed on 

 the culms, affords the most obvious characters of distinction : it is of two kinds, the spike and 

 the panicle. 



CspicaX is a number of flowers without footstalks, that closely surround one 



principal, simple straight culm. ^S 



nerata, (glomefdtaj, ^ 

 Sesleria ccerulea, 

 ticillated rverticillataj 



as in 



O -"«v./*,^jviv>v>i:7 V/iX I.X1C iSIJl 



on that account to be placed in whirls, as in Pankum verticillatum. 

 :-rowed, (secunda), when the flowers are arranged on one side, as in Nardus 

 mdrical, (cylindrica), when the spike is equally covered with flowers Panici 

 .ar, (RneaHs), that is, slender, and of equal thickness, as in Cynosurus erucafc 



(ventricosa) 



agrestis 



(foUosaJ 



V. 



