COMPOSITE. 65 



Akenes thick, in the ray mostly 3-sided and in the disk compressed, more or less margined, 

 without pappus, or sometimes with 2 to 4 teeth or short awns. Leaves opposite and heads 

 small. 



-J — H — -* — Bracts of the many-flowered receptacle concave or complicate, loosely embracing 

 or subtending the disk-akenes, mostly persistent. 



++ Bays uniformly none, the flowers all hermaphrodite and fertile : involucre dry or partly 

 so : akenes not flat nor margined : pappus of slender awns or none. 



90. MELANTHERA. Involucre hemispherical; the disk in fruit globular, and squarrose 

 with the mostly pointed rather rigid striate concave bracts of the convex or low-conical 

 receptacle ; bracts of the involucre ovate to lanceolate, thickish, nerveless, in 2 or 3 series, 

 somewhat equal in length. Corolla 5-lobed, with campanulate-oblong ampliate throat. 

 Style-branches tipped with a subulate hispid appendage. Akenes thick and short, com- 

 pressed-quadrangular, somewhat obpyramidal, with broad truncate summit : pappus of 2 or 

 more slender caducous awns. Leaves opposite, petioled. 



9 1 . VARILL A. Involucre short, of rather few and small linear-lanceolate appressed-imbri- 

 cate and mostly few-striate bracts, similar to those of the at length high-conical or oblong 

 ■receptacle. Corolla with narrow cylindraceous throat, 5-toothed. Style-branches with short 

 and obtuse or minutely apiculate conical tips. Akenes narrow, linear-oblong, terete, rather 

 thin-walled, smooth, evenly 8-15-nerved : pappus setulose or none. Shrubby or suffruticose. 



92. ISOCARPHA. Involucre, receptacle, and dry bracts nearly of the preceding genus. 

 Corolla similar but small. Style-branches with subulate tips. Akenes 4-5-angled, small, 

 little compressed, destitute of pappus. Herbaceous. 



93. SPILANTHES. Some (exotic) species have no ray-flowers, and akenes not flat, witli 

 pappus also wanting : these resemble Isocarpha. 



++ ++ Rays present, but in several genera occasionally wanting : involucre commonly her- 

 baceous or foliaceous, or partly so. 



= Receptacle high, from conical to columnar or subulate, at least in fruit. (Here Gym- 

 nolomia, as to two species, would be sought. ) 



a. Rays fertile, or not rarely wanting : style-branches of the disk-flowers truncate and some- 

 times penicillate at tip : akenes small : leaves opposite. 



93. SPILANTHES. Involucre of a few somewhat herbaceous loosely appressed bracts. 

 Bracts of the receptacle soft and chaffy, shorter than the flowers, more or less conduplicate 

 and embracing the akenes, at length falling with them. Disk-corollas 4-5-toothed. Akenes 

 of the ray triquetrous or obcompressed ; those of the disk either moderately or much com- 

 pressed and with acute or nerve-like margins, sometimes ciliate-fimbriate. Pappus a 

 setiform awn from one or more of the angles, or none. 



b. Rays sterile (imperfectly styliferous in Echinacea, otherwise completely neutral), soon 

 drooping, sometimes marcescent, the ligule with very short tube or none : style-branches 

 tipped with an acute or obtuse hispid appendage : leaves mostly alternate. 



94. ECHINACEA. Involucre imbricated in 2 or 3 or more series and squarrose ; its bracts 

 lanceolate. Disk at first only convex, becoming ovoid and the receptacle acutely conical. 

 Chaffy bracts of the latter firm and completely persistent, linear-lanceolate, carinate-concave, 

 acuminate into a rigid and spinescent cusp, surpassing the disk-flowers. Ligules elongated 

 and pendent in age, rose-colored or rose-purple, marcescent, usually imperfectly styliferous. 

 Disk-corollas cylindraceous, with 5 erect teeth and almost no proper tube (a ring upou 

 which the stamens are inserted). Akenes suberose-cartilaginous, acutely quadrangular, 

 somewhat obpyramidal, with a thick coroniform pappus more or less extended into triangular 

 teeth at the angles ; the basal areola central. 



95. RUDBECKIA. Involucre looser, spreading, more foliaceous. Disk from hemispheri- 

 cal or globose to columnar, and receptacle from acutely conical to cylindrical and subulate ; 

 its chaffy bracts not spinescent, but sometimes soft-pointed. Ligules yellow or partly (rarely 

 wholly) brown-purple. Disk-corollas with a short but usually a manifest proper tube. 

 Akenes 4-angled, prismatic, in some species quadrangular-compressed, or in one nearly 

 terete. Pappus a coriaceous or firm-scarious and often 4-toothed crown, sometimes deep 

 and cupuliform, sometimes obsolete, or none. 



5 



