238 COMPOSITE. (COMPOSITE FAMILY.) 



large, somewhat corymbose ; outer scales of the involucre broadly ovate, leafy ; 

 rays iiumerous, narrow ; achenia 4 sided, smooth. Mountains of North Caro- 

 liua. Introduced. 



29. PLUCHEA, Cass. 



Heads many-flowered, discoid; the central flowers mostly perfect, but ster- 

 ile, witli the corolla dilated and o-cleft; the others pistillate, slender, slightly 

 toothed. Anthers bicaudate. Scales of the involucre imbricated. Receptacle 

 flat, mostly naked. Achenia grooved or angled. Pappus a single row of 

 capillary slightly scabrous bristles. Odorous mostly pubescent and glandu- 

 lar herbs, with alternate ovate or oblong serrate leaves. Heads of purplish 

 flowers corymbose. 



1. P. bifrODS, DC. Stem simple, or sparingly branched ; leaves oblong, 

 acute, denticulate, strongly reticulated and rugose, cordate and clasping; 

 heads clustered; involucre pubescent and viscid. Margins of pine barren 

 ponds, Florida to North Carolina. Sept. Stem l-2 high. Flowers pale 

 purple or white. 



2. P, foetida, DC. Minutely pubescent and glandular; leaves large, 

 membranaceous, ovate-lanceolate, acuminate, serrate, tapering into a petiole; 

 corymbs axillary and terminal ; heads rather small, numerous, on slender pedi- 

 cels ; involucre smoothish ; often purplish. Damp soil, Florida, and north- 

 ward. Sept. Stem 2 - 5 high. Leaves 5' - 8' long, resinous-dotted. Flow 

 ers purple. 



3. P. camphorata, DC. Minutely pubescent and glandular-viscid; 

 leaves ovate-lanceolate or oblong-ovate, acute, denticulate, nearly sessile; 

 heads rather large, in a dense corymb, on short and stout pedicels ; scales of 

 the involucre pubescent, the inner ones long-acuminate. Salt marshes, Flor- 

 ida to North Carolina. Sept. Stem l-2 high; the branches few and 

 erect. Leaves 2' -3' long. Flowers light purple. 



4. P. purpurascens, DC. Tomentose and glandular; leaves ovate- 

 lanceolate, acute or acuminate, sharply and somewhat erosely serrate, on 

 slender petioles ; heads rather sinnl!. on slender pedicels, loosely corymbose; 

 scales of the involucre pubescent, the inner ones lanceolate, acute. Swamps 

 and low ground, Florida. Sept. Stem l-2 high, with numerous spread- 

 ing branches. Leaves 2'- 4' long. Flowers bluish purple. 



30. PTEROCAULON, Ell. 



Heads and flowers chiefly as in Pluchea. Scales of the involucre lanceolate, 

 imbricated in several rows, caducous. Receptacle minutely hairy. Achenia 

 angled, pubescent. Pappus of numerous equal capillary bristles, longer than 

 the involucre. Perennial herbs. Leaves lanceolate, densely tomentose and 

 hoary beneath, the margins broadly decurrent on the stem. Heads compactly 

 spiked. 



1. P. pycnostachyum, Ell. Stem rarely branched, l-2 high; 

 leaves wavy, smooth above ; spike thick, woolly ; flowers white. Damp pine 

 barrens, Florida to North Carolina. June -July. 



