24 TEE TRUE GRASSES. 



opposite the scutellum a small scale-like appendage, the 

 epiblast (ep in Fig. 6, E, 0, P). It is especially clear in 

 Stipa (Fig. 6, 0, P), and yet better developed in Zizania 

 (where it is as long as the plumule), but is entirely 

 lacking in many grasses (Rye, Maize, and Barlej') ; gen- 

 erally it is merely a delicate formation consisting of 

 parenchyma without fibro-vascular bundles, and its 

 morphological nature is still doubtful. Yet the view 

 that it is a rudimentary second cotyledon is the most 

 reasonable, for among other things this makes compre- 

 hensible the surprising position of the first leaf of the 

 plumule just above (not opposite to) the scutellum. The 

 plumule of the embryo consists of a very short, often in- 

 distinct internode of the axis (epicotyl) and of two to 

 four leaves, and according to the development of the 

 former the plumule is sessile or petioled. The first 

 leaf, the germ-sheath, surrounds the others like a closed 

 tube, which breaks through the ground with its hard 

 point at the time of germination, and opens at its apex 

 after a time in order to allow the exit of the second leaf. 

 It is colorless or pale green or frequently reddish. 

 Many authors consider it a part of the cotyledon, a view 

 which is certainly incorrect, for in many grasses (all 

 Panicece, Andropogonece, Maydece, many Festucece and 

 Hordece) it is clearly separated from the scutellum at the 

 time of germination by a distinct internode (epicotyl) 

 which is often much elongated (compare Fig. 6, L, st). 

 In others (Triticum, etc.) this epicotyl is very short or 

 entirely lacking, so that the back of the sheath may even 

 be grown to the scutellum. 



The majority of grasses have only one radicle, and 

 grow therefore with a primary root ; in addition to which, 

 especially from the epicotyl, new roots soon arise which 

 finally exceed the main root in growth. In several 

 grasses, especially in the cereals, and also in Coix 

 lachryma and others, the foundation of these secondary 

 roots is already laid before germination, usually in the 

 hypocotyl (the axis below the insertion of the scutellum i ; 

 seldom, and only to a rudimentary degree, in the epicotyl 

 (Zea, Fig. 6, L, iv^. The plane of these secondary roots 



