CONCERNING THE PAPPUS. 93 
305 309 
ig. 8302. A seed of the Cotton-plant, with its tuft of coma, or cotton. 
ig. 808. A seed of the Cotton-tree (Populus), with its silky coma. 
ig. 304. A winged seed of the Catalpa. 
ig. 805. Achenium of Eclipta; it has no pappus. 
ig. 806. Achenium of Horseweed ; scarcely any pappus. 
ig. 307, Achenium of Sunflower; has two awns for pappus. 
ig. 808. Achenium of Ageratum ; has five sepals for pappus. 
ig. 809. Achenium of Blue Milkweed; has abundant pappns. 
ig. 810. Achenium 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. Ina word, the seed may be fledged with a coma, but 
the 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. What is the distinction between coma and pappus? 
