CONCERNING THE PAPPUS. 



Fig 302. A seed of the Cotton-plant, with its tuft of coma, or cotton. 



Fig. 303. A seed of the Cotton-tree (Populus), with its silky coma. 



Fig. 304. A winged seed of the Catalpa. 



Fig. 305. Achenium of Eclipta; it has no pappus. 



Fig. 306. Achenium of Horseweed; scarcely any pappus. 



Fig. 307. Achenium of Sunflower; has two awns for pappus. 



Fig. 308. Achenium of Ageratum ; has five sepals for pappus. 



Fig. 809. Achenium of Blue Milkweed; has abundant pappus. 



Fig. 310. Acheuium of Wild Lettuce ; with pappus raised on a beak 



188. The learner must distinguish between the coma of a 

 seed and the pappus of a fruit. The down of Thistle or Dan- 

 delion is pappus, for the little fruit on which it grows is not 

 merely a seed, but a pericarp (achenium), also containing one 

 seed. In a word, the seed may be fledged with a coma, but 

 fas fruit is fledged with a pappus, both intended as wings 

 to bear away the seed to distant places. (See Class Book of 

 Botany, 485.) 



188. iVTiat is the distinction between coma and pappus? 



