ESSENTIAL PARTS. 13 



compressed, when the branches are so short as to give 

 it more or less of the spike form. 



This whole arrangement will be seen in Fig. 1, which 

 represents a stalk of the common annual spear grass 

 (Poa annua), a plant familiar to every one as often 

 troublesome in gravel walks and on hard, dry soils. 

 Here the joint, the stem, or culm, clasped by the sheath ' 

 of the leaf, the leaf itself, the ligule, and the spikelets, 

 all distinctly appear ; and the reader will do well to 

 make himself familiar with the few technical terms used, 

 by a study of this figure, in connection with Fig. 2, 

 where the spikelet is so magnified as to show the florets 

 and the calyx very distinctly, all of which are generally 

 very easily seen with the naked eye, and Fig. 3, show- 

 ing a floret still more magnified, with its two palese, the 

 outer pale being the longer and generally keeled ; that 

 is, having one, three, or more longitudinal ribs, often 

 having on the back, base, or summit, an awn or beard 

 of different lengths, as in the oat and brome grasses, 

 the inner pale with two separate fringed ribs, each on 

 a fold at the side. The calyx, cup, or outer scale 

 of the spikelet, is shown very much magnified in Fig. 

 4, composed of two glumes, the upper and lower, the 

 upper glume being the larger. The glumes and pales 

 are known also by the name of husks or chaff, and are -, 

 removed if possible in cleaning the seed, as in the j 

 grains used for their meal. One or both of the glumes 

 are sometimes wanting. 



In Fig. 5 is shown the pistil magnified, consisting of 

 the nectary, composed of one or two fleshy scales (in 

 some plants of this family both on one side, in others 

 entirely wanting), and the germ, ovary, or seed-bearing 

 portion of the pistil The stamens are also .seen in the 

 same figure, consisting each of a bag filled with a fine 

 powder or pollen, supported upon a stalk or filament 

 2 



