240 



COMPOSITE FAMILY 



Stamens 5, on the corolla-tube, usually themselves united into 

 an inner tube. Style divided into 2 branches. Ovary 1-celled, 

 l-ovuled, maturing into an akene, which resembles a seed and is 

 crowned by the pappus when that is present. 



d 



Types of Heads in Compositae. — 1. Head of Sunflower, cut vertically 

 (radiate). 2. Head of Cudweed, cut vertically (discoid). 3. Head as in 

 the Chicory Tribe (flowers all strap-shaped). — r, ray; d, disk; i, involucre 

 of bracts; r, receptacle; p, peduncle. 



^ 



Details of Flowers in Compositae. — 1. Ray-flower of an Aster, with 

 pappus of bristles. 2. Disk-flower from the same head. 3. Ak^ne of 

 Rigiopappus, with pappus of flattened awns. 4. Akene of Chaenactis, with 

 pappus of scales. 5. Akene of Dandelion, with beak and pappus of bristles. 

 6. A single feathery pappus-bristle of Thistle. — a, akene; c, corolla; p, pap- 

 pus; r, ray; s, stigma. 



Artificial Key to the Genera of Compositae. 



To use this key, first determine the series (I., II., or III.) to which 

 the plant belongs. Then turn to the key for that series and run the plant 

 through in the ordinary manner. A synopsis of the tribes will be found 

 at end of key. 



I. Flowers of two sorts, the outer series with rays, the central ones tubular 



and toothed. Series I. Radiate Compositae, key on p. 241. 



II. Flowers all alike, tubular and toothed; none with rays. Series II. Dis- 



coid Compositae, key on p. 242. 



III. Flowers all with strap-shaped corolla, therefore all resembling ray- 

 flowers, there being no tubular and regularly toothed corollas. Series 

 III. Chicory Tribe, key on p. 243. 



