274 PBAGTIGAL BOTANY. 



Oil. Herbs 1-3 feet high. Pappus-crown 5-lobed or 

 toothed. Kecejitacle convex. Heads corymbed. 



Tanacetum. 

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

 lete. ' Invohicral scales oval, with white, scarious margins. 

 Receptacle conical. Heads on simple peduncles. 



Matricaria discoidea, D. C. 

 01^. (907.) Pai)i)us of many capillary bristles. Aclienia 



sometimes 5-angled 915 



Pappus a circle of 5-20 chaffy scales 913 



913. Leaves alternate 914 



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

 gle row of almost horny, oval, ol)tuse scales. Flowers flesh- 

 color. In shallow water. Sclerolepis verticillata, Cass. 

 014, Leaves ovate-oblong. Pappus of awned scales 

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

 flowered in a compoimd head ; flowers purplish. 



Elephantopus Carolinianus, Willd. 



Leaves once- U) twice-piniiately 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 scabiosaeus, L'Her. 



Olo. Leaves allernate 918 



Leaves opposite (or whorled) 916 



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

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

 Heads ill peduncled axillary corymbs. 



Mikania scandens, Willd. 

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



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

 white or purp e. Heads generally corymbose. 



Eupatorium (925). 

 Receptacle conical. Heads in terminal corymbs; 

 flowers sky blue, becoming purplish. Leaves triangular- 

 ovate, slightly cordate, toothed. 



Conoclinium coelestinum, D. C. 



018. Flowers in the heads ;ill alike and perfect. (Heads 

 homogamous) 919 



