278 PRACTICAL BOTANY. 



the decurrent base of the lobed and toothed, somewhat prick- 

 ly leaves. Heads large ; involucral scales spiny. 



Onopordon Acanthium, L. 

 Recej^tacle not honeycombed 940 



040, Involucral scales hooked. Leaves large, petioled, 

 upper ones ovate, the lower heart-shaped. Heads solitary, or 

 clustered ; flowers purplish. Lappa Major, Gaertn. 



{Burdock.) 

 Involucral scales not hooked 941 



041. Pappus threefold — namely, 10 short, horny teeth, 10 

 slender, rigid bristles, and as many shorter ones. Flowers 

 yellow. Cnicus benedictus, L. 



Pappus of one sort; its bristles united at the base 

 in a ring. Leaves sinuate, or pinnatifid, spiny, usually decur- 

 rent. Flowers i)urplish 942 



049. Pappus plumose. Cirsium. 



Pappus capillary. Heads solitary, drooping. 



Carduus nutans, L. 



043. (905.) Receptacle chaffy — that is, with pales among 

 the flowers 964 



Receptacle naked, or deeply honeycombed 944 



044. Recej^table deeply honeycombed. Heads solitary, 

 globular, at the summit of each stem. Rays neutral, long, 

 narrowly wedge-shaped, yellow ; disk-flowers at lengtli pur- 

 ple. Receptacle strongly convex. Achenia silky-villous. 

 Pappus of 7-9 oblong-lanceolate chaffy scales. Leaves ob- 

 lanceolate. Baldwinia uniflora, Nutt. 



Receptacle not honeycombed 945 



04c». Pappus of 5-12 scales, or of many capillary bristles 



946 



Pappus none, or of a few short awns or a crown. 



Leaves alternate 961 



046. Pappus of 5-12 scales 947 



Papj3us of many capillary bristles 949 



047. Leaves alternate 948 



Leaves opposite. Pappus-scales deeply cleft into 

 capillary bristles. Leaves dotted, pinnately parted into nar- 



