THE SUNFLOWER FAMILY 141 



of the other species; from 1/20 to 1/10 of an inch in diameter, 

 nearly round, somewhat flattened on the side bearing the scar. 

 The whole seed, except the depression in the scar, is covered 

 with prickly hairs, giving it a grayish colour. The scar surface 

 is brown, rugose. The hairs are sometimes broken off by thresh- 

 ing and cleaning the seed. 



THE SUNFLOWER FAMILY (Compositae). 



This, the largest family of flowering plants, includes ten 

 to twelve thousand species and is represented in all parts of the 

 world by economic, medicinal and ornamental plants, and by 

 some poisonous and weed pests. The characteristics of the 

 family are well marked. The roots and rootstocks contain 

 a chemical principle, inulin, which is poisonous and gives to 

 many plants their medicinal properties. The flowers of all 

 are composite; that is, composed of many small flowers or florets 

 standing together on expanded enlargements, known as re- 

 ceptacles, at the ends of the stalks. Individually, these flower 

 heads, or collections of many florets, have the appearance of 

 simple flowers and are popularly so spoken of; as, for instance, 

 the flower of a sunflower, a daisy or a dandelion, while in reality 

 each one is a large number of flowers grouped together at the 

 end of a common footstalk, and what appears to be a calyx 

 is a cluster of small bracts. A striking characteristic of this 

 family is that the stamens are united at their edges into a vertical 

 tube with the pistil inside. The calyx of the florets, when present, 

 is modified in fruit into a ring of silky bristles, awns, teeth 

 or scales, which is called the pappus. The florets of composite 

 flowers are of two kinds, both of which may sometimes be seen 

 in the same flower head, as in Common Sunflower. The 

 marginal or ray flowers are strap-shaped, and the smaller centre 

 or disc flowers are tubular. When the flower head has ray 

 flowers, either throughout or round the edge, it is termed radiate; 



