482 COMPOSITAE (COMPOSITE FAMILY) 



-- - Ray-flowers with ligule wanting or reduced to 2-3 teeth. 



37. Parthenice. Involucral bracts mostly in 1 series, the inner minute or wanting. A 



caulescent annual. 



38. Bolophyta. A caespitose, acaulescent perennial. 



* * None of the flowers ligulate, the fertile few (1-5), with minute tubular corolla or none. 



-t- Heads alike. 



39. Oxytenia. Achenes with a terminal areola surrounded by a disk. Involucres of 5 



dilated, ovate, rigidly acuminate bracts. 



40. Iva. Achenes short, thick. Involucre of a few roundish bracts. 



41. Dicoria. Achenes flattened, wing-margined. Involucres of 5 ovate-oblong herbaceous 



bracts and 1 or 2 scarious ones subtending the pistillate flowers. 

 H- )- Heads of two kinds, the fertile with a tuberculate or bur-like involucre. 



42. Ambrosia. Bracts of staminate involucre united; fertile involucre with a single row 



of tubercles near the summit. Fruiting head '1 -seeded. 



43. Franseria. Staminate involucre as in no. 42; sterile involucre with more than 1 row 



of tubercles or prickles. Fruiting head 2-4-seeded. 



44. Xanthium. Bracts of the staminate involucre distinct. Fruiting head 1-4-celled, 



1-4-beaked. 



* * * Disk-flowers fertile, the corollas funnel-form; anthers blackish; pappus none, or a 



crown or cup, or of 1-2 chaffy awns, neither capillary nor of several uniform chaffy 



scales; leaves more commonly opposite. 

 t- Rays persistent upon the mature achenes. 



45. Crassina. Achenes of the disk compressed. Leaves entire. 



46. Heliopsis. Achenes 4-sided. Leaves toothed. 



t- H- Rays deciduous or wanting. Chaff scale-like, embracing or subtending \he achenes; 



the involucre of two or more rows of separate bracts. 



H- Receptacle high conical or columnar in fruit; pappus none or a short crown or awn. 

 = Rays pistillate, sterile. 



47. Brauneria. Rays rose-colored (rarely yellow). Achenes short, 4-sided. Chaff 



spinescent. 



48. Gymnolomia. Rays yellow. Achenes compressed-quadrangular. 



= = Rays neutral. 



49. Rudbeckia. Achenes 4-sided or terete, flat at the top, marginless. 



50. Ratibida. Achene flattened laterally and margined. 



M- -H- Receptacle flat to convex. 

 = Achenes not winged or very flat. 



51. Balsamorrhiza. Achenes 3-4-angled. Pappus none. Chaff linear-lanceolate. 



52. Wyethia. Achenes elongated, 4-5-winged. Pappus a laciniate crown, one of the 



teeth usually elongated and persistent, or all distinct. 



53. Helianthus. Achenes flattened, bearing 2 very deciduous, chaffy pointed scales and 



rarely minute intermediate ones. 



= = Achenes thin-edged, margined or winged, often awned. 



54. Helianthella. Rays neutral. Achenes merely margined. 



55. Ximenesia. Rays fertile. Achenes winged. 



* * * * Rays few and neutral, or wanting; achenes obcompressed, i. e., flattened parallel 



with the scales of the involucre (rarely terete); involucre double, the outer spreading 

 and often foliaceous; receptacle flat; leaves opposite. 

 K- Plants not glandular-viscid. 



56. Coreopsis. Involucral bracts distinct or united only at base. Pappus of 2 (or rarely 



more) scales, teeth, or awns, which are naked, not barbed, sometimes obsolete 

 or a mere crown. 



57. Bidens. Involucral bracts distinct or united merely at base. Pappus of 2 or more 



rigid and persistent barbed awns or teeth. 



58. Thelesperma. Inner involucre connate to the middle. Achenes terete. Awns 2, 



retrorsely hispid. 



+- i- Plants more or less glandular viscid. 



59. Madia. Bracts of involucre uniserial, more or less inclosing the achenes of the fertile 



rays. 



60. Layia. Bracts of the involucre flattened on the back below, with abruptly dilated 



thin margins abruptly infolded so as to inclose the ray achene. 



Tribe VI. HELENIEAE. Nearly as Tribe V, but receptacle not chaffy (somewhat so in 

 nos. 75 and 70). In our genera, the disk-flowers perfect and fertile; the pappus a row 

 of several chaffy scales (bristly-dissected in no. 78); the involucre hardly at all im- 

 bricated (partly scarious in nos. 64, 65 and 66). 



* Herbage without oil-glands. 

 H- Ligules persistent on the striate achenes and becoming papery. 



61. Psilostrophe. Plants more or less woolly. 



- *- Ligules deciduous or wanting. 

 M- Achenes flat, with only marginal nerves. 



62. Pericome. Involucral bracts lightly connate by their edges into a campanulate cup. 



M- -H- Achenes angled (not flat), nerved or striate. 



= Receptacle not chaffy. 



a. At least the tips of the involucral bracts petaloid or scarious. 

 b. Heads rayless. 



63. Hymenopappus. Involucre broadly campanulate; the bracts 6-12. Lobes of the disk 



corollas spreading or reflexed. 



bb. Heads radiate. 



64. Leucampyx. Ligules ochroleucous or white, merely toothed. 



65. Polypteris. Ligules purple, deeply cleft. 



ad. Involucral bracts not petaloid or scarious. 



