182 SINGENESIA. KECESSARIA, 



594. CENTAUREA. i. (Knapweed, &c.) 



Calix various. Hays funnelform, irregular. 

 Tieceptacle setose. Fappus simple, often piiose. 



Gererally herbaceous; leaves alternate, simple or pinna- 

 tificl; flowers terminal. 



Species. 1. C. Cijanns. (Blue-bottle). Not very com- 

 monly naturalized. 2. nigra. 3. jacea. 4. benedicta. o; 

 calcitrapa. All naturalized, not indigenous. 



A vast and compound genus indigenous to Europe, 

 Barbarv, Egvpt, the Levant and Siberia. !n the gouthera 

 hemisphere "only a single doubtful species has been hi^ 

 therto discovered by Commerson at Monte Video. 



dRDER. IV.— POLYGAMIA MECESSARIA. 



(Radial florets only fertile.) 



595. CH APT ALT A. Ventenat. 



Calix subimbricated, many-leaved. Feminine 

 fords of two kinds, in 2 series, external radiate, 

 internal naked. Discal Jlorets bilabiate. Be- 

 ceptacle naked. Pappus capillary. 



Scapes 1-fiowered; leaves radical, entire, usually to- 

 irentose beneath. — Pappus mostly stipitate. 



Species. 1. C. inlegn'folia. Leaves oblong-obovate, re- 

 trorsely denticulate, beneath tomentose; flower nutant. 

 Hab. From Virginia to Florida, near open sandy swamps. 

 —Root perennial, fibrous. Leaves covered on the under 

 side with a cotton like tomentum; scape tomentose, much 

 longer than the leaf. Calix oblong, formed of nearly a 

 simple series of leaflets, a few of the external ones short- 

 er. Rays narrow, 35 or 20; external discal florets in a 

 single row, feminine without corolla; internal hermaphro- 

 dite, bilabiate, upper lip 3-toothed, lower bifid. Anthers 

 each conspicuously bisetose at the base. 



An American genus of 7 or 8 species nearly allied to 

 rerdicium, extending to Monte Video. 



