208 



FLOWERS OF GEASSES. 



and then this corolla assumes a bilabiate or two-lipped form, as seen 

 in the division of Compositse called Labiatiflorae. In Composite there 

 are often two kinds of florets associated in the same head. Thus, in 

 the Daisy there are irregular Hgulate white florets on the outside or in 

 the ray, while there are regular tubular yellow florets in the centre or 

 disc. In Scsevola and in Honeysuckle the corolla is split down to 

 its base, so as to resemble somewhat the ligulate form. 



Flowers of Grasses and Sedges. — In these plants, in place 

 of verticUlate leaves forming the flower, there are alternate scales 

 or glumes. The flowers of grasses usually occur in spikelets (fig. 

 327), which consist of one or two glumes, a, covering several flowers, 

 b. The spikelets are associated in spikes or panicles. In Wheat 



[Fig. 327. 



Fig. 328. 



Fig. 329. 



Fig. 330. 



these spikelets are arranged alternately along a common rachis. 

 Each spikelet (fig. 327) consists of two empty glumes, a a, having 

 the form represented in figure 328, and enclosing flowers which are 

 composed of scales (pale® or glumellte), delineated in figures 329 and 

 330 — the former being the outer, and the latter the inner pale or 

 glumella — which are placed at different heights in an alternate manner. 

 In the flower of the Oat (fig. 331), after removing the outer pale or 

 glumella, the inner one, pi, is seen with two scales (lodiculae.or squamae), 

 sq, at the base, enclosing the essential organs of r'eproduction. The 

 palesB of grasses are called by some flowering glumes, while hypogynous 

 scales (lodiculee) within this are considered as the rudimentary 

 perianth. In Wheat (Triticum) there are two empty glumes, and 



Fig. 327. A spikelet of Wheat [Trititnim), consisting of two glumes, a a, enclosing several 

 flowers, h h, whicli are composed of two pales (paleas) covering the essential organs of repro- 

 duction. The stamens, s, hang out by long slender thread-like filaments. The individual 

 glumes aud paleae are placed alternately on the floral axis. Fig. 328. One of the glumes 

 of Wheat (Tritwum), seen in profile. These glumes are bracts or floral leaves which consti- 

 tute the outer covering of the spikelet. They are placed at different levels, following the 

 law of alternation. The glume is marked with three ribs. Fig. 329. External (outer) 

 palea or glumella of the flower of Wheat. It is a glumaceous scale marked with two ribs on 

 each side of the jnidrib. Fig. 330. Internal (inner) palea or glumella of the flower of 

 Wheat. It is thinner and more membranous than the outer glumella (flowering glume), its 

 edges are folded inwards and its apex is bifid. 



