170 
(3) Herbaceous (rarely suffruticose): rays fertile (sometimes neutral in Verbesina) 
or occasionally wanting: achenes (or some of them) with winged margins, 
none villous ciliate. 
69. Zexmenia. Receptacle flat or convex: achenes 3-sided or flat, 1 to 3-awned, 
the awns connected by dilated buses or with intermediate and separate or confluent 
persistent scales, 
70, Verbesina. Receptacle from convex to conical: achenes 3-sided or flat, 1 to 
3-awned, with no intermediate scales, andeven the awns sometimes obsolete; leaves 
apt to be decurrent. 
*** * © Rays few, neutral or wanting: achenes obcompressed (flattened parallel with 
the bracts of the involucre): chaff flat or hardly concave: receptacle flat: leaves 
mostly opposite. 
+ Involucre single. 
71. Synedrella. Chaff scarious: achenes (or some of them) wing-margined, the 
wings commonly lacerate or undulate, in the ray often 3-sided, the angles or wings 
surmounted each by a rigid naked awn. 
+ + Involucre double. 
= Rays always neutral (rarely wanting): achenes never beaked nor with retrorsely 
barbed awns. 
72. Coreopsis. Pappusof 2 (rarely more) scales, teeth, or awns, which are naked 
or barbed upward, sometimes obsolete or a mere crown. 
== Rays fertile or neutral, or wanting: awns of pappus when present retrorsely 
barbed or hispid. 
a. Involueral bracts distinet, or united only at base. 
73. Bidens. Achenes neither winged nor beaked, 2 to 5-awned: awns mostly per- 
sistent: rays neutral, yellow or white, sometimes wanting. 
74. Cosmos. Achenes slender and beaked; rays white or rose-color: awns apt to 
be deciduous. 
75. Heterospermum. Achenes dimorphous; the outer with winged or callous 
margin: the inner narrower, attenuate upward and marginless, these and sometimes 
the outer with two awns: rays fertile. 
b. Inner involucral bracts united into a cup. 
76, Thelesperma. Chaff white-scarious: rays neutral or wanting: achenes terete, 
marginless and beakless, the abrupt summit crowned with a pair of persistent stout 
awns or scales, or sometimes pappus obsolete. 
«** * * * Heads radiate or discoid: disk-flowers all perfect and fertile: achenes 
turbinate, 5-angled: pappus of several chaffy scales, 
77. Marshallia. Rays none: involucre of narrow equal leafy bracts: disk-flow- 
ers purplish: leaves alternate, entire. 
Tribe VI. HELENIOIDE’. Nearly as in tribe V, but receptacle not chaffy, and 
herbage often punctate. 
*Involucre of broad bracts imbricated in two or more series: ligules not persistent: 
achenes terete and several-nerved: heads many-flowered and radiate, the ray-flow- 
ers fertile: no oil-glands. 
78. Clappia. Involucre hemispherical: rays 12 to 15, linear: achenes equaled by 
the very slender fimbrille of the receptacle: pappus of numerous rigid hispidulous 
bristles: fruticulose, with alternate fleshy leaves. 
**Involucre of narrow equal erect bracts: ligules persistent and becoming papery 
on the usually striate-nerved achenes: herbage more or less white-woolly: no 
glands, 
