COMPOSITE 665 



or 5-cleft, known as tubular flowers (Fig. 293); and one in which 

 the petals are united into a short tube, with an upper part that forms 

 a large, strap-shaped, usually 5-toothed limb, known as ligulate 

 flowers (Figs. 293 and 294). 



In some of the plants of the Compositse the head consists of 

 ligulate flowers only, but in the larger number of plants the head 

 is composed of both tubular and ligulate flowers or tubular flowers 

 alone and accordingly two main groups or sub-families are distin- 

 guished. The sub-family in which all of the flowers are ligulate is 

 known as Liguliflorae, or Cichoriacese, by those who give the group 

 the rank of a family. This group includes plants like dandelion, 

 chicory, lettuce, and Hieracium. The group or sub-family in which 

 the flowers are all tubular or ligulate on the margin only is known 

 as the Tubuliflorae. When the head consists only of tubular flowers 

 it is called discoid, but when ligulate flowers are also present it is 

 called radiate. When the heads are radiate, as in the common daisy, 

 the TUBULAR FLOWERS are spoken of as disk-flowers, and the ligulate 

 flowers as RAY-FLOWERS. The disk-flowers are usually perfect, while 

 the ray-flowers are pistillate or neutral (without either stamens or 

 pistils). By some systematists the Tubuliflorae are divided into 

 groups which have been given the rank of families. This division 

 is based especially on the characters of the stamens. In a small 

 group represented by the ragweed and known as the Ambrosiacese, 

 the anthers, while close together (connivent), are not united, and the 

 corolla in the marginal or pistillate flowers is reduced to a short tube 

 or ring. In a large group, which includes probably 10,000 species 

 and which is considered to be the Compositse proper, the stamens in 

 the tubular flowers are syngenesious and the marginal or ray-flowers 

 are distinctly ligulate. This group includes the daisy, sunflower, 

 golden-rod, aster, thistle, and most of the plants which yield official 

 drugs. 



The Compositse are characterized by having inulin, in the cell- 

 sap of the parenchyma cells, especially in the underground organs. 

 Inulin usually occurs in solution, but may be caused to separate, by 

 the addition of alcohol, in the form of sphserite aggregates which 

 resemble in structure starch grains, but the aggregates are not enclosed 

 by distinct membrane. Laticiferous vessels are common to all of 

 the plants of the Cichoriacese. These vessels occur either on the 

 inner face of the strands of leptome or are distributed in the pericycle 

 of the stems. Schizogenous resin-canals are distributed among the 

 parenchyma cells of the primary cortex and pith, of a large number of 

 the genera of the Tubuliflorse. Secretory cavities and elongated 



