Monographs Details:
Authority:
Acevedo-RodrÃguez, Pedro & collaborators. 1996. Flora of St. John, U.S. Virgin Islands. Mem. New York Bot. Gard. 78: 1-581.
Acevedo-RodrÃguez, Pedro & collaborators. 1996. Flora of St. John, U.S. Virgin Islands. Mem. New York Bot. Gard. 78: 1-581.
Family:
Asteraceae
Asteraceae
Description:
Genus Description - Annual or perennial herbs, less commonly shrubs or vines; stems usually conspicuously striate. Leaves simple to deeply lobed or variously compound, opposite or becoming alternate above; leaflets often ovate or lanceolate and serrate or more deeply lobed; petioles and rachis (when present) frequently narrowly winged. Inflorescence terminal, solitary or of a few long-peduncled heads. Heads with many flowers, radiate or less commonly discoid; involucre of 2 dissimilar series of bracts, the outer bracts green, narrow, the inner bracts brown with broadly hyaline margins, equal in length, broader than the outer bracts; receptacle convex or flat, paleate, the palea flat, usually resembling the inner involucral bracts. Ray flowers mostly sterile, in a single series, usually 5-12; corollas yellow or white. Disk flowers few to many, bisexual; corollas usually yellow; anthers usually black. Achenes weakly compressed tangentially, variously angled or ribbed, glabrous or pubescent; pappus of (0-)1-6, usually retrorsely barbed, erect or spreading awns.
Genus Description - Annual or perennial herbs, less commonly shrubs or vines; stems usually conspicuously striate. Leaves simple to deeply lobed or variously compound, opposite or becoming alternate above; leaflets often ovate or lanceolate and serrate or more deeply lobed; petioles and rachis (when present) frequently narrowly winged. Inflorescence terminal, solitary or of a few long-peduncled heads. Heads with many flowers, radiate or less commonly discoid; involucre of 2 dissimilar series of bracts, the outer bracts green, narrow, the inner bracts brown with broadly hyaline margins, equal in length, broader than the outer bracts; receptacle convex or flat, paleate, the palea flat, usually resembling the inner involucral bracts. Ray flowers mostly sterile, in a single series, usually 5-12; corollas yellow or white. Disk flowers few to many, bisexual; corollas usually yellow; anthers usually black. Achenes weakly compressed tangentially, variously angled or ribbed, glabrous or pubescent; pappus of (0-)1-6, usually retrorsely barbed, erect or spreading awns.