222 PRACTICAL LESSONS IN SCIENCE. 



Remove the leaves and study the stem, noting its shape and 

 surface; make a section through a joint or node and note the 

 partition separating the cavities of the internodes. Make a 

 cross section and note the vascular bundles and the cortical or 

 bark layer with its clusters of chlorophyll cells. Make longitu- 

 dinal sections and find the parts shown in the cross sections. 



In studying the leaves notice the split sheath with the thin 

 membraneous ligule, and compare the two as to texture, form 

 and use. Notice the shape of the blade, the veins, their direction, 

 and relations to each other; make a cross section and locate the 

 vascular bundles; the green tissue between is the mesophyll, or 

 parenchyma of the leaf. 



The stem of the plant is the main axis of inflorescence; its 

 branches are secondary axes, and some of these are branched, 

 forming a flower cluster called a panicle. At the extremity of the 

 smaller branches there is a cluster of two or three flowers called 

 a spikelet. At the base of the spikelet notice two leaves which 

 enclose the flowers, called the glumes ; notice their position with 

 respect to each other, also note their shape, surface and veins. 

 The flattened axis on which the flowers stand is the rachis of the 

 spikelet; note the relative size of the flower inclosed by the 

 glumes and the tuft of hairs at the base of the lowest flower. 



Take the lowest flower of the spikelet, and note the bract 

 called the lower palet which almost incloses the flower ; notice 

 carefully the size, shape, surface, texture, number of nerves, etc., of 

 the palet. It sometimes bears a bristle or awn ; if so, note its 

 position, length, texture, etc. Cut away the lower palet without 

 injuring the flower, and note another bract called the upper palet. 

 Study all its parts and compare it with the lower palet, also note 

 two little scales at the base of the upper palet. Notice the num- 

 ber of stamens, the character of the filament and anthers, and 

 the appearance of the pollen. Notice the top-shaped ovary, the 

 thread-like styles, and the feather-like stigmas. Compare the 

 lowest flower of the spikelet with the others. 



In studying the ripe grain, strip off the chaff and note the 

 whitish hairs, especially at the upper end; the longitudinal 



