CARDUACEAE 1157 
Bracts of the involucre relatively broad, not embracing 
achenes. 119. BAHIA. 
Achenes 5-10-ribbed or 5-10-angled. 
Involucre many-flowered : pappus present. 
Outer bracts of the involucre separate. 120. TETRANEURIS. 
Outer bracts of the involucre united. 121. PICRADENIA. 
Involucre few-flowered : pappus wanting. 122. FLAVERIA. 
Achenes flat. 123. LAPHAMIA. 
** Bracts of the involucre spreading or reflexed. 
Involuere of subulate or linear bracts: disk-corollas each with 
a very short tube and glandular-pubescent lobes. 124. HELENIUM. 
Involucre of foliaceous bracts without an inner series of hya- 
line bracts: disk-corollas each with a manifest tube and 
glabrous lobes. 125. AMBLYOLEPIS. 
b. Receptacle with bristle-like chaff. 126. GAILLARDIA. 
B. Pu especially the leaves and braets of the involucre, with oil 
glands. 
Bracts of the involucre more or less united: stigmas of the disk-flowers 
elongated. 
Bracts of the involucre united at the base. 127. BoEBERA. 
Bracts of the involucre united into a cup. 128. THYMOPHYLLA. 
Bracts of the involucre distinct: stigmas of the disk-flowers very short. 129. PEcTIs. 
TRIBE VII. ANTHEMIDEAE. 
Receptacle chaffy. 
Achenes terete, at least not flattened : involucre hemispheric: heads large. 130. ANTHEMIS. 
Achenes flattened : involucre obovoid to campanulate : heads small. 131. ACHILLEA. 
Receptacle naked, or sometimes merely pubescent. 
Ray-flowers usually present. 
Receptacle flat to hemispheric: bracts of the involucre in several series. 132. CHRYSANTHEMUM. 
Receptacle conic to ovoid: bracts of the involucre in few series. 183. MATRICARIA. 
Ray-flowers wanting, 
Heads corymbed : pappus a short crown. 134. TANACETUM. 
Heads spicate, racemose or panicled : pappus wanting. 
Pistillate flowers with corollas. 135. ARTEMISIA. 
Pistillate flowers without corollas. 136. SOLIVA. 
TRIBE VIII. SENECIONEAE. 
Bracts of thei nvolucre lax, the broad outer ones strongly overlapping the 
nner. 137. HAPLOESTHES. 
Bracts of the involucre erect-converging, narrow, not much overlapping. 
Leaves opposite, sometimes mainly basal: pappus-bristles rigid. 138. ARNICA. 
Leaves alternate: pappus-bristles soft. 
Corollas white, whitish or pinkish: ray-flowers wanting. 
Disk-flowers perfect: marginal-flowers pistillate. 139. ERECHTITES. 
Disk-flowers and marginal-flowers perfect. 
Involuere of about 5 main bracts. 140. MESADENIA. 
Involucre of 12-15 principal bracts. 141. SYNOSMA. 
Corollas yellow: ray-flowers usually or typically present. 142. SENECIO. 
TRIBE IX. CYNAREAE. 
Achenes inserted on the receptacle by their bases, not oblique. 
Bracts of the involucre hooked at the tip: leaves not bristly. 143. ARCTIUM. 
Bracts of the involucre not hooked : leaves bristly. 144. CARDUUS. 
Achenes obliquely inserted on the receptacle. 
Heads not sessile in bristly leaves. 145. CENTAUREA. 
Heads sessile in bristly leaves. 146. CNICUS. 
TRIBE X. MUTISIEAE. 
Corollas essentially regular, deeply 5-lobed : shrubby plants. 147. GOCHNATIA. 
Corollas all bilabiate, or the marginal ones ligulate : herbaceous plants. 
Heads heterogamous, the marginal fiowers radiate. 148. THY RSANTHEMA. 
Heads homogamous, all the corollas bilabiate. 149. PEREZIA. 
1. VERNONIA Schreb. 
Perennial, caulescent herbs or shrubby plants, with upright stems. Leaves usually 
alternate : blades mostly toothed. Heads discoid, in panicled or corymbed open cymes 
Involucres hemispheric to cylindric or nearly turbinate: bracts imbricated in several series. 
Receptacle flat, naked. Corolla regular: lobes 5. Anthers sagittate, not caudate. Stig- 
mas subulate, hispid. Achenes 8-10-ribbed, truncate. Pappus double, the outer series of 
scales or stout bristles, the inner of numerous, rough, hair-like bristles. Some of the 
species are called IRON WEED. The plants flower during the summer and fall, or in the 
extreme south somewhat earlier. 
A. Leaves mainly or all cauline. 
a. Bracts of the involucre or some of them with filiform or subulate tips. X 
Involucres over 15 mm. broad. 1. V. rinila. 
Involucres less than 10 mm. broad. 
Leaf-blades smooth above. t ; 
Pappus purple or purplish. 2. V. Noveboracensis. 
Pappus straw-colored. 
Outer bracts of the involucre filiform or subulate-filifo-m. 3. V. tomentosa. 
