COMPOSITE. (COMPOSITE FAMILY.) 225 



40. MELANTHERA, Rohr. 



Heads many-flowered ; the flowers all tubular and perfect, 5-cleft. Scales of 

 the involucre imbricated in 2 rows. Chaff of the convex receptacle rigid, per- 

 sistent, partly sheathing the flowers. Achenia 4-angled, short, truncate at the 

 apex. Pappus of 2 -several rough rigid deciduous awns or bristles. Rough 

 perennial herbs, with branching 3 - 4-angled stems, opposite undivided or 3- 

 lobed serrate petioled leaves, and scattered heads of white flowers, on long 

 peduncles. Anthers black. 



1. M. hastata, Michx. Stem commonly spotted; leaves varying from 

 lanceolate to ovate, entire, or more or less hastate-3-lobed, serrate ; scales of the 

 involucre lanceolate, acute ; chaff of the receptacle spine-pointed. Light rich 

 soil, Florida to South Carolina. Aug. and Sept. Stem 3 - 6 high. 



2. M. deltoidea, Michx. Leaves deltoid-ovate, undivided ; scales of the 

 involucre ovate ; chaff of the receptacle obtuse, mucronate. South Florida. 



41. ZINNIA, L. 



Heads many-flowered ; the ray-flowers pistillate ; those of the disk perfect, 

 tubular, with 5 velvety lobes. Scales of the involucre imbricated, oval or round- 

 ish, margined. Chaff of the conical receptacle clasping the disk-flowers. Ray- 

 flowers oblong, rigid persistent. Achenia of the disk compressed, with a 1 -2- 

 awned pappus; those of the rays 3-angled, destitute of a pappus. Annual 

 herbs, with sessile entire 3-ribbed leaves, and solitary heads, on long inflated 

 peduncles. 



1. Z. multiflora, L. Stem erect, hairy, branching; leaves oblong-lanceo- 

 late ; chaff of the receptacle obtuse ; pappus of the disk-flowers 1-awned ; rays 

 red or purple. Waste places, Florida to North Carolina. Introduced. July- 

 Sept. Stem 1 - 2 high. Rays sometimes fading into yellow. 



42. HELIOPSIS, Pers. 



Heads many-flowered ; the ray-flowers pistillate ; those of the disk tubular, 

 perfect, 5-toothed. Scales of the involucre in 2 - 3 rows ; the exterior longer, 

 leafy. Chaff of the conical receptacle lanceolate, partly clasping the smooth 4- 

 angled truncated achenia. Pappus none. Perennial herbs with the habit of 

 Helianthus. Rays yellow. 



1. H. laevis, Pers. Smooth; stem slender, branching; leaves ovate or 

 ovate-lanceolate, acute or acuminate, sharply serrate, 3-ribbed at the base, on 

 slender petioles ; peduncles elongated ; scales of the involucre obtuse ; rays 

 deciduous. Dry open woods, Florida, and northward. Aug. and Sept. 

 Stem 2 - 3 high. Leaves 2' - 3' long, sometimes scabrous. 



43. TETRAGONOTHECA, Dill. 



Heads many-flowered ; the ray-flowers (6-9) pistillate ; those of the disk tu- 

 bular, 5-toothed, perfect. Involucre double, 4-sided ; the exterior of 4 ovate 



