No. 439.] NORTHERN GA MOPE TA LOUS FLOWERS, 449 



its enfolding bracts often resembles a single (lower, and was 

 termed by the older botanists a compound fiower. The life his- 

 tory of the individual florets may be conveniently studied in the 

 garden sunflower, where they are of comparatively large size. 



The Cichoriaceae, or chicory family, are often treated as a 

 tribe of the Composite. There are 8 white, 53 yellow, 5 red, 

 2 purple and 5 blue species. All of the flowers of the head are 

 strap-shaped or ligulate, as in the dandelion. This species Tav- 



ities the plants are so numerous that the inflorescence covers 

 with a bright sheet of golden yellow entire hillsides. The visit- 

 ors are numerous ; in Low Germany Muller collected 67 Apidae, 

 7 Lepidoptera, 25 Diptera and 16 other insects. Most of the 

 genera of this family have yellow flowers as Hieracium (hawk- 

 weed), Latiica (lettuce) and Sonchus (sow thistle), but as a rule 

 they are much less conspicuous than the dandelion and have 

 fewer visitors. The great number of yellow flowers in this 

 family have already been referred to under the Scrophulariaceae. 

 Cichorium intybus (chicory) has large bright blue flowers with 

 white and pink variations. 



The Ambrosiacea\ or ragweed family, are composed of small 

 greenish flowers, which in the absence of insects have reverted 

 to wind-fertilization. In Ambrosia the corolla has been lost. 

 At an earlier stage the flowers were homogamous or self-fer- 

 tilized, as is still the case in Senecio vulgaris which is visited 

 rarely by insects. The flowers excellently illustrate the fact 

 that inconspicuousness is due to the absence of insects. 



In the Composite the flowers are either tubular and all alike, 

 when the head is called discoid ; or the disk flowers are tubular 

 and the marginal flowers are ligulate, when the head is radiate. 

 There are 21 green, 126 white, 209 yellow, 4 red, 64 purple, 

 and 59 blue flowers. 1 When the heads are discoid the flowers 

 are all of the same color, but when they are radiate they are 

 frequently bicolored. In the garden daisy, or Bcllis pen nnis. 

 the disk flowers are yellow, and the ray flowers are white, pink, 

 or purple, with purple bracts. In Townsendia the disk flowers 



