SYNANTHERE^l. 373 



acuminate, bluntish at the base, minutely hispidulous ; involucre loose, subrecurved : exterior 

 scales foliaceous, oblong-lanceolate, pointed, somewhat exceeding the ray ; paleaj incurved- 

 mucronate, obovate-oblong. — The determination of this species rests only on DCs incom- 

 plete diagnosis. — Exterior scales of the involucre 6'" long ; ligules 8-10, oblong, 2-dentate 

 little longer than the disk. — Hab. Dominica !, Imr. ; [Cuba]. 



32. BIDENS, L. 



Head radiate or discoid : the ray-flowers sterile. Involucre 2-serial. Receptacle flattish 

 paleaceous : palese deciduous with the achenium. Style-branches hispidulous above acute! 

 Achenium compressed or tetragonal, 2-4(-6)-awned : awns persistent, retrorsely hispid.— 

 Leaves opposite, serrate or divided ; heads corymbose or single, yellow or white. 



Sect. Psilocakp^ea, DC. — Achenium tetragonal, linear, tapering above. 



103. B. leucanthus, W. Annual, glabrous or nearly so ; stem erect, tetragonal; 

 leaves pinnatisect, 1-3-jugal (rarely simple) s segments ovate-lanceolate or ovate acumi- 

 nate; heads corymbose : ray white or none ; exterior involucral scales oppressed lanceo- 

 late, ciliate or puberidous ; achenia glabrous or hispidulous above : awns 2—4, diverging in 

 the exterior, erect in the central larger ones. — Desc. Fl. 8. t. 583. — Coreopsis' L. B. pilo- 

 sus, L. : the discoid form. B. brachycarpus and anthriscoides, DC. Coreopsis coronata L. 

 {ex Plum. Ed. Burnt, t. 53./. 2), and C. alba, L. {ex Herm. Parad. t. 124). — A remark- 

 able form, with all leaves simple, hispidulous achenia, and whitish-pubescent involucres, was 

 collected by Dr. Alexander, but transitions into the common B. leucanthus occur among 

 Mr. March's specimens. — Hab. Jamaica !, all coll., a common weed ; Antigua !, Wullschl. • 

 Trinidad !, Sch., Cr. ; [Florida ; Cuba ! and Mexico ! to Brazil 1 and Chili ! ; Pacific islands! 

 to trop. Australia !, New Zealand 1, and East Indies ! ; Madeira !, trop. Africa ! to the Cape !]. 



104. B. Coreopsidis, DC. Stem herbaceous, scandent, cylindrical ; leaves pinnati- 

 sect, l(-2)-jugal, superior often, all rarely simple: segments ovate-lanceolate or oblong-lan- 

 ceolate, acuminate ; heads corymbose : ray yellow ; exterior involucral scales squarrose- 

 spreading, linear ; achenium hispidulous on two margins, or glabrescent : awns 2 (-4), di- 

 verging. — Sm. Spicil. t. 22 j Bot. Reg. t. 7. — Coreopsis reptans, Z. C. incisa, Ker. C. 

 chrysantha, L. {Plum. Ed. Burm. t. 53./. 1), is perhaps a form with smaller ligules. B. 

 tereticaulis, DC. : the common, glabrous form. B. squarrosus, Kth. : a hairy variety, with 

 the leaves densely pubescent beneath. B. speciosus, Gardn. ! — Ligules large, usually entire 

 at the top. — Hab. Jamaica!, all coll., in waste places; Antigua!, Nichols., Wullschl., 

 S. Vincent !, Guild. ; [Texas ! and Cuba ! to Brazil !]. 



105. B. bipinnatus, L. Annual, glabrous ; stem erect, tetragonal ; leaves 2-3-pin- 

 natisect (rarely simply pinnatisect) : segments small, cuneate- oblong or lanceolate ; heads 

 lon^-peduncled : ray -flowers few, yellow, subincluded ; exterior involucral scales spreading, 

 linear ; achenium long, glabrous or hispidulous above : awns 4-2, suberect or little diver- 

 ging. B. cynapiifolius, Kth. B. portoricensis, Spreng. B. parviflorus, W. •. ex specim. 



Turczan. — Hab. Jamaica {Lun.) ; Antigua!, Wullschl., a weed; [Connecticut and Cali- 

 fornia ! to Buenos Ayres 1 ; Southern Siberia !; Southern Tirolia ! to trop. Africa !]. 



33. COSMOS, Cav. 



Character of Bidens, but awns of the beaked achenium deciduous or abortive. — Leaves 

 2-pinnatisect ; heads radiate, long-peduncled. 



106 C caudatus, Kth. Glabrous or nearly so ; leaf-segments lanceolate, scabrous on 

 the margin • exterior involucral scales nearly as long as the inner series; ray rosy ; ache- 

 nium tanerinsr from the middle into an upwardly scabrous beak : awns 2, horizontal.— 4'-7' 

 mum te P* n "f *™ m ™ e b k i nc l u ded) 10"'-12'" long.— Hab. Jamaica !, Bancr., Wits. ; 

 iSiuatrXw^DSbic.!, Imr., S. Vincent !, Guild.; Trinidad !, Sch.; [Key West, 

 Cuba ! and Mexico ! to Ecuador !]. 



107 C snlfureus, Cav., var. leiorhynchn., Gr Glabrous or nearly so : leaf-seg- 

 I 1 1 * „i ml „ „n the margin ; exterior involucral scales linear, exceeded by the 



