CARDUACEAE. 447 



1. Tetranthus bahamensis Britton, Bull. N. Y. Bot. Gard. 5: 318. 1907. 



Steins smooth, slender, creeping, 3-6 cm. long. Leaves ovate, about 4 mm. 

 long and 3 mm. wide, obtuse at the apex, rounded or subcordate at the base, 

 glabrous on both sides, the veins very obscure, the petioles about 3 mm. long, 

 sparingly pilose; heads solitary, 4-flowered, on sparingly pilose peduncles, 

 about 1 cm. long; involucre bracts 4, obovate, about 1.5 mm. long, and 1 mm. 

 wide, 3-nerved, sparingly pilose without and slightly ciliate; corolla about 1 

 mm. long, glabrous, the lobes slightly shorter than the tube; anthers large, 

 apiculate; style glabrous, 0.5 mm. long, its branches glandular-pilose; achenes 

 bluntly quadrangular, glabrous, 0.5 mm. long. 



In crevices of rocks under shrubs, Great Ragged Island, Acklin's Island, Mari- 

 guana. Endemic. BAHAMA TETKANTHUS. 



15. ACANTHOSPERMUM Schrank, PI. Ear. Hort. Monac. pi. 53. 1819. 



Annual rather coarse herbs, with pubescent foliage and erect or creeping 

 stems, opposite broad, often leathery, toothed leaves, and radiate but incon- 

 spicuous heads, axillary to leaf-like bracts. Involucre double, an outer one 

 of flat herbaceous bracts, and an inner one of several smaller bracts which 

 become bur-like and fall away enclosing an achene at maturity. Receptacle 

 concave or convex. Ray-flowers few, in 1 series, the rays very small, yellowish, 

 concave or hooded. Disk-flowers perfect, sterile. Anthers entire at the base. 

 Achenes broadest above the middle, slightly curved. Pappus wanting. [Greek, 

 thorn-seed, from the prickly, bur-like fruits.] About 3 species, natives of 

 tropical America. Type species: Acanthospermum brasilium Schrank. 



1. Acanthospermum humile (Sw.) DC. Prodr. 5: 522. 1836. 

 Melampodium humile Sw. Prodr. 114. 1788. 



Villous-pubescent, branched, erect, 3-9 dm. high. Leaves ovate, 2-4 cm. 

 long, very coarsely dentate, obtuse or acute at the apex, obtuse or subtruncate 

 at the base, the broadly margined petioles 1-2 cm. long, often coarsely 

 toothed; heads sessile or nearly so; pistillate flowers 3-7; inner bracts of the 

 involucre bearing short hooked prickles and 2 1 rigid subulate beaks 2-3 mm. 

 long. 



A weed in cultivated and waste grounds near Nassau, New Providence : south- 

 eastern United States; Cuba; Hispaniola ; Culebrita ; St. Martin; Tobago; Jamaica. 

 SPINY-BUR. 



16. PARTHENIUM L. 6p. PI. 988. 1753. 



Erect, mostly pubescent -or canescent herbs, or shrubs, with alternate 

 leaves, and small corymbose or paniculate heads of both tubular and radiate 

 white or yellow flowers. Involucre broadly campanulate or hemispheric, its 

 bracts imbricated in 2 or 3 series, obtuse, appressed, nearly equal. Receptacle 

 convex or conic, chaffy, the chaff membranous, surrounding the disk-flowers. 

 Ray-flowers about 5, pistillate, fertile, their ligules sliort, broad, 2-toothed or 

 obcordate. Disk-flowers perfect, sterile, their corollas 5-toothed, the style 

 undivided. Anthers entire at the base. Achenes compressed, keeled on the 

 inner face, margined, bearing the persistent rays on the summit. Pappus of 

 2-3 scales or awns. [Greek, virgin.] About 10 American species. Type 

 species: Parthenium Hysterophorus L. 



