1252 CARDUACEAE 



ered : bracts narrow, few, appressed. Receptacle conic or oblong, manifestly chaffy. Kay. 

 flowers wanting. Disk-flowers perfect, fruit-producing : corollas white or whitish. Bract- 

 lets similar to the bracts of the involucre. Stigmas subulate-tipped. Achenes narrow, 

 or 4-5-angled. Pappus wanting. 



1. Isocarpha oppositifolia (L.) R. Br. Stem finely pubescent, 3-10 dm. tall, 

 branched above : leaf -blades spatulate-oblong, oblong-lanceolate or ovate, 2.5-9 cm. long, 

 entire or shallowly toothed, 3-ribbed, narrowed into petiole-like bases : heads solitary or 

 clustered : involucres turbinate-campanulate, 3-4 mm. high ; bracts firm, ribbed, the outer 

 subulate, the inner linear: disk ovoid, higher than the involucre : achenes 1.5 mm. long, 

 sharply angled. 



In dry soil, southern Texas. Also in the West Indies and Mexico. Spring to fall. 



85. VARfLLA A. Gray. 



Shrubs or shrubby herbs, with glabrous foliage. Leaves opposite or alternate : blades 

 fleshy, narrow, entire, sessile. Heads discoid, solitary or several in corymbose cymes. 

 Involucres short, several-flowered : bracts few, narrow, appressed, usually striate. Kecep- 

 tacle becoming conic or oblong, chaffy. Ray-flowers wanting. Disk-flowers perfect, 

 fruit-producing : corollas tubular, yellow. Bractlets similar to the bracts of the involucre, 

 Stigmas with obtuse or apiculate conic tips. Achenes terete, 8-15-nerved, smooth. Pappus 

 of several bristles, or wanting. 



1. Varilla Texana A. Gray. Shrubby, several dm. tall, glabrous or nearly so, finally 

 diffusely branched. Leaves numerous, approximate on the caudex-like stem or its branches ; 

 blades terete, linear, 1-2. 5 cm. long, obtuse : peduncles slender : involucre broad ; bracts 

 subulate to linear-subulate, the inner 5-6 mm. long, acuminate : disk rounded, much sur- 

 passing the involucre : pappus wanting. 



In saline soil, southern Texas and adjacent Mexico. 



86. SPILANTHES Jacq. 



Annual or perennial, often acrid caulescent herbs, usually with spreading branches. 

 Leaves opposite : blades flat, often toothed, petioled. Heads radiate or discoid, peduncled. 

 Involucres campanulate : bracts narrow, in about 2 series, rather loosely appressed. Ke- 

 ceptacle convex or elongated, chaffy. Kay-flowers pistillate, fruit-producing : ligules white 

 or yellow. Disk-flowers perfect, fruit-producing, each embraced by a bractlet with which 

 the achene falls away : corollas yellow. Stigmas of the disk -flowers elongated, sometimes 

 brush -like. Achenes various : those of the ray 3-angled or somewhat flattened : those of 

 the disk flattened, margined. Pappus of 1 or several awns. 



1. Spilanthes ripens (Walt.) Michx. Stems decumbent or creeping, 2-8 dm. long, 

 hirsute or glabrate. Leaf -blades ovate to lanceolate, 2-6 cm. long, denticulate to coarsely 

 serrate, each gradually, or usually abruptly, narrowed into a short petiole : peduncles 2-10 

 cm. long : involucres campanulate or becoming rather flat ; bracts lanceolate to oblong, 4-5 

 mm. long, acute : ray-flowers with yellow ligules 5 mm. long : disk ovoid, 1 cm. high at 

 maturity: achenes 1.5 mm. long, tuberculate and hispidulous in age. 



In low grounds, North Carolina to Missouri, Florida and Texas. Spring to fall. 



87. GYMNOLOMIAH.B.K. 



Annual or perennial caulescent herbs or shrubby plants, with pubescent foliage. Leaves 

 alternate or opposite : blades narrow, entire or toothed. Heads radiate, rather conspicu- 

 ous. Involucres hemispheric or campanulate : bracts narrow, in 2-3 series, the inner ones 

 somewhat longer than the outer. Keceptacle more or less conic, chaffy. Kay-flowers pistil- 

 late, not fruit-producing : ligules yellow. Disk-flowers perfect, fruit-producing, with 

 yellow or brownish corollas. Stigmas of the disk-flowers obtuse or with acute appendages. 

 Achenes of the ray inane, those of the disk 4-angled, either somewhat flattened or turgid, 

 truncate. Pappus a denticulate crown, or wanting. 



Annual plant : receptacle conic, becoming columnar : Georgian species. 1. G. Porteri. 



Perennial plant : receptacle low-convex : Texano-Mexican species. 2. G. tenuifolia. 



1. Gymnolomia Pdrteri A. Gray. Annual, herbaceous^ Stems 2-10 dm. tall, loosely 

 branching, sparingly hispid : leaves mostly alternate ; blades narrowly linear to narrowly 



