LXXV. COMPOSITiE. 



311 



T'heJUnoera are moreover said to be 



Of the 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 m the form of a strap. 



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



Umnogamous, where they consist wholly of perfect flowers; 



Heteros-amoiis, where the flowers of the disk are perfect or staminate, while those of the ray or margin 

 are pistilFate or neutral ; 



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



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



Discoid, where all the flowers are tubular, aa in the thoroughwr/rt : 



MonoEcicms, where the same head has both staminate and pistillate flowers ; . 



Heterocepha/ous, where the same individual plant has some of its heads whollyofstaxxunate, and others 

 wholly of pistillate flowers. 



Dicecimts, where the same species has some of its individuals with stammate heads only, and pthera 

 with pistillate heads only. The anthers are usually appendiculate, that is, prolonged at the summit mto 

 a membranous appendage. The achenia are termed 



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

 dandelion ; 



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



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



F[G. A7.—\. Helianthus strumosus— head radiate. 2. Vertical section of the head, showing the scales 

 of the involucre, and a single disk-flower remaining upon the convex receptacle. 3. A perfect disk-flower 

 magnified, showing the achenium, the 2 awns of the pappu.s, the Stoothed tubular corolla, the 5 stamena 

 united around the branched style, and the chaff scale at base. 4. Head (radiate) of Solidago cwsia. 

 5. A pistillate, ligulate flower of the ray. 6. A perfect disk 11. 7. A (radiant) head of Taraxacum Dens- 

 Jeonis. 8. A nertect, ligulate fl. 9. Achenium, with it.s long beak and plumose pappus. 10. A (radiant) 

 head of Nabalu.s altissimuj*. 11. A (lower. 12. Lai)}ia major, head discoid. 13. A flower. 14. One of 

 the hooked scalc.H. 15. A (discoid) IkiuI of Eupatonum iniri.ureum. 16. A flower. 17. Ambrosia aite- 

 misiafblia. is. .Staminate head enlarged. 19. I'ialiliatc involucre enlarged. 20. The fertile flower. 



Conspectus of the Genera. 



< Leaves alternate. . ._ • %\ 

 ( rorolla.4 cyanic. { Leaves opposite or vcrticiUato. § 2 



rdiicoid. (Corollas yellow 



j U.caves alternate. . 

 j ( Rays yellow. . \ Leaves opposite or all radical. 

 1 < U.eavesoi)i)osite or all radical. 

 I radiate. ( Ra>-8 cyanic. . ( Leaves alternate. . 

 .radiant. 



15 



27 



