LXXV. COMPOSITiE. 



311 



Vhejlmoers are moreover said to be 



■Qflhe. disk, where they stand in or near the centre of the head; 



■Of the ray, when they stand in the outer circle or circumference of the head: 



Ligulate (strap-shaped), when the limb is split on one side and spread open in the form of a strap. 



Tubular, when they are monopetalous with a regular limb. The heacls are termed 



Bmnosainous, where they consist «holly of perfect flowers; 



Heterofaninus, where the flswers of the disk are perfect or staroinate, while those of the ray or margio 

 p-re pistillate or neutral : 



Radiant, where the flowers are all ligulate, as in the dandelion ; 



Radiate, where those of the ray or margin only are Ugulate, the rest being tubular, as ia Aster ; 



Discoid, where all the flowers are tubular, as in the thoTough^or/rt ; 



Moncecious, where the same head has both st;iminate and pistillate flowers ; 



Heterocephalims, where the same individual plant has some of its heads wholly of staminate, and othere 

 u>holly of pistillate flowers. 



DicECious, where the same species has some of its indi\'iduals with staminate heads only, and others 

 avith pistillate heads only. The anthers are usually appendiculate, that is, prolonged at Lhe suimnit into 

 a membranous appendage. The achenia are termed 



Rostrate, when they are prolonged at the summit into a slender neck supporting the pappus, as in the 

 ■dandelion ; 



Compressed, when they are flattened parallel with the diameter of the head ; 



Otcoinpressed, when flattened parallel with the circumference of the head. 



FIG. 47.— 1. Helianthus strumosus — head radiate. 2. Vertical section of the head, showing the scales 

 tf the involucre, and a single disk-flower remaining upon the conve.x receptacle. 3. A perfect disk-flower 

 magnified, showing the achenium, the 2 awns of tfie pappus, the 5-toothed tubular corolla, the 5 stamens 

 united around the branched style, and the chaff-scale at base. 4. Head (radiate) of Solidago c;Esia. 

 5. A pistillate, ligulate flower of the ray. 6. A perfect disk fl. 7. A (radiant) head of Taraxacum Dens- 

 leonis. 8. A perfect, lijulats fl. 9. Achenium, with its long beak and plumose pappus, io. A (radiant) 

 head of Nabalus altissimus. 11. A flower. V2. Lappa mpjor, head discoid. 13. A flower. 14. One of 

 tlie hooked scales. 15. A (discoid) head of Eupatorium purpureum. 16. A flower. 17. Ambrosia arta- 

 taisiatblia. 18. Staminate head enlarged. 19. Pistillate involucre enlarged. SO. The fertile flower. 



CMUpeclus of the Genera. 



5 Leaves alternate. . . . § 1 



J Corollas cyanic. \ Leaves opposite or verticillate. § 2 



("discoid. \ Corollas yellow § 3 



I 5 Leaves alternate. . . - § 4 



I Rays yellow. . \ Leaves opposite or all radical. § 5 



i Leaves opposite or all radical. | 6 



J radiate. ( Rays cyanic. . (Leaves alternate. . . . §7 



Heads Lradiant. § 8 



27 



