EXOGENS. 77 



four little nuts, or naked seeds, and irregular corollas. 

 The Composite family is very extensive. It includes 

 all such plants as the Thistle, Sunflower, Daisy, Aster, 

 and Chrysanthemum. There are about twelve thou- 

 sand species in this family, distributed all over the 

 globe. They are generally herbaceous plants, and 

 often contain a milky fluid, or latex. The flowers are 

 placed on a common expanded receptacle, crowded to- 

 gether into a capitulum, or head, and surrounded by 

 a general involucre of densely crowded bracts. The 

 florets of the central part of the capitulum are often 

 of a different structure and color from those of the 

 margin, and the two kinds are distinguished as florets 

 of the disk and florets of the ray. 



4. Another class of Exogens also have calyx and 

 corolla, but the corolla has distinct petals, and the 

 stamens are attached to the calyx. 



The Umbelliferous family is found in this division, 

 and contains culinary plants, such as Carrot, Celery, 

 Parsley, and Parsnip ; medicinal herbs, as Caraway, 

 Fennel, Coriander, and Assaf oatida ; and some poison- 

 ous plants, as Hemlock and Fool's Parsley. This 

 family is named from the mode of its inflorescence. 

 An umbel, like the capitulum, has the stem terminat- 

 ing in a number of flowers, but each separate flower 

 is stalked. The umbel is simple when the main stem 

 or peduncle ends in a number of separate stalked 

 flowers, as in the Cherry, compound when it branches 



