10 



THE BLADE. 



the side oi^posite the blade, thougli exceptional cases are cited 

 where tlie sheaths are closed, as in Brotnufi (chess), Molica 

 (inelic grass), and some others. Tlie sheaths of the upper leaves 

 of most grasses are split down to the node, but those of the lower 

 leaves in very many species are closed. In some cases the sheaths 

 are closed at an early stage of development, but later they are 

 split open part of the way down by the enlargement of tlie grow- 

 ing culm and the young leaves as they push upwards. This is 

 illustrated in Fig. 7. 



Fio.T.— (I, A tliin cross section of a yoiinnleafof Poa |>r(ite/i.tw with tin; blade condu- 

 plicate, and tin' surroundiiitj sheath closed; h, a section still lov/er down, showing 

 three closed sheaths; c, still lower down near a node, where Ave leaves have the 

 sheaths closed. 1 xlO.— (Sudworth.) 



At the ui)per tnd of the sheath there is often a membranous 

 scale, tongue, or fringe, called the h'r/nle. The reader will con- 

 sult Fig. ,')!. ".nd observe the ligule of a leaf of June grass. That 

 part of the leaf, which spreads away from the culm, is known 

 us the 



Blade or lamina^ and is usually sessile and slender, tapering to a 

 point. 



To the ordinary observer the blades of grasses seem to be very 

 nearly alike. Even Linnants thought so, but to the botanist of 

 to-day they j) resent very marked differences. 



The abortive leaves on root-stocks generally consist mainly of 

 rudimentary sheaths. Commonly, all the leaves on a stem are 

 much alike, but in some cases the lower leaves are quite unlike 

 those above. The lower leaves of some species of Bambusa 

 (bamboo), Ori/zopsis asj^crifoUa (mountain rice), Fanicum 



