274 PUAGTIGAL BOTANY. 



911. Herbs 1-3 feet high. Pappus-crown S-lobed or 

 toothed. Receptacle convex. Heads corymbed. 



Tanacetum. 

 Herb low, 6-S inches high. Pappus-crown obso- 

 lete. Involucral scales oval, with white, scarious margins. 

 Receptacle conical. Heads on simple peduncles. 



Matricaria discoidea, D. C. 

 913. (907.) Pappus of many capillary bristles. Acheuia 



sometimes 5-angled 915 



Pappus a circle of 5-20 chaffy scales 913 



913. Leaves alternate 914 



Leaves whorled in 5s or 6s, linear. Pappus a sin- 

 gle row of almost horny, oval, obtuse scales. Flowers flesh- 

 color. In shallow water. Sclerolepis verticiUata, Cass. 

 '914;. Leaves ovate-oblong. Pappus of awned scales 

 (stout bristles, chaffy dilated at the base). Heads 3- to 5- 

 flowered in a compound head ; flowers purplish. 



Elephantopus Carolinianus, Willd. 



Leaves once- to twice-pinnately parted into linear 



or oblong lobes. Pappus of 15-20 small, very thin, blunt 



scales in a single row. Heads many-flowered, separate, not 



in a compound head, corymbed. 



Hymenopappus scabiosaaus, L'Her. 



915. Leaves alternate 918 



Leaves opposite (or whorled) 916 



916. Involucral scales 4 only. Heads 4-flowered. 

 Climbing herbs. Leaves heart-shaped, or halberd-form. 

 Heads in peduncled axillary corymbs. 



Mikania scandens, Willd. 

 Involucral scales more than 4. ^No climbers.. .917 



917. Receptacle flat. Involucral scales 8-20. Flowers 

 white or purp e. Heads generally corymbose. 



Eupatorium (925). 

 Receptacle corneal. Heads in terminal corymbs ; 

 flowers sky-blue, becoming purplish. Leaves triangular- 

 ovate, slightly cordate, toothed. 



Conoclinium coelestiuiuu, D. C. 



918. Flowers in the heads all alike and perfect. (Heads 

 homogamous) 919 



