230 



PLANT STRUCTURES 



is the 'bilabiate, or " two-lipped," in which two of the petals 

 usually organize to form one lip, and the other three form 



the other lip (Figs. 210, 

 c,d,e, 212,213). The two 

 lips may be nearly equal, 

 the upper may stand high 

 or overarch the lower, the 

 lower may project more or 

 less conspicuously, etc. 



126. Inflorescence. 

 Very often flowers are soli- 

 tary, either on the end of 



FIG. 213. Flower of a Labiate ( Teuoium}, 

 showing the calyx of coalesced sepals, 

 the sympetalous and two-lipped (bilabi- 

 ate) corolla with three petals (middle one 

 largest) in the lower lip and two small 

 ones in the upper, and the stamens and 

 style emerging through a slit on the up- 

 per side of the tube; a sympetalous and 

 zygomorphic flower. After BHIQUET. 



a stem or branch (Figs. 

 231, 236), or in the axil 

 of a leaf (Fig. 258). But 



such cases grade insensibly into others where a definite 

 region of the plant is set aside to produce flowers (Figs. 

 253, 260). Such a region forms what is called the inflo- 

 rescence. The various ways in which flowers are arranged 

 in an inflorescence have received technical names, but they 

 do not enter into our purpose here. They are simply dif- 

 ferent ways in which plants seek to display their flowers 

 so as to favor pollination and seed distribution. 



There are several tendencies, however, which may be 

 noted. Some groups incline to loose clusters, either elon- 

 gated (Fig. 260) or flat-topped (Fig. 253) ; others prefer 

 large and often solitary flowers (Fig. 258) to a cluster of 

 smaller ones ; but in the highest groups there is a distinct 

 tendency to reduce the size of the flowers, increase their 

 number, and mass them into a compact cluster. This ten- 

 dency reaches its highest expression in the greatest family 

 of the Angiosperms, the Composite, of which the sunflower 

 or dandelion can be taken as an illustration (Figs. 261, 262), 

 in which numerous small flowers are closely packed together 

 in a compact cluster which resembles a single large flower. 

 It does not follow that all very compact inflorescences in- 



