COMPOSITE. (COMPOSITE FAMILY.) 181 



* Heads with two kinds of flowers, discoid ; pistillate flowers with a small tubular corolla. 

 29 1VA. Pistillate flowers 1 - 5 in the margin. Achenia thickish. Pappus none. 

 * * Heads of two sorts, one containing stamiuate, the other pistillate flowers, both borne on 



the same plant; the pistillate only 1-2, in a closed involucre resembling an acheuium or 



a bur ; the staniinate several, in an open cup-shaped involucre. 

 80- AMBROSIA. Fertile involucre (fruit) small, 1-flowered, pointed and often tubercled. 



81. XANTU1UM. Fertile involucre (fruit) an oblong prickly bur, 2-celled, 2-flowered. 



Subtribe 2. HELIANTHEJE. Heads radiate, or rarely discoid ; the rays ligulate, the disk- 

 flowers all perfect and fertile. Receptacle chaffy. Anthers blackish, tailless. Pappua 

 none, or a crown or cup, or of one or two chaffy awns, never capillary, nor of several 

 uniform chaffy scales. Leaves more commonly opposite. 



* Hays pistillate and fertile : achenia 3 - 4-sided, slightly if at all flattened 

 H- Involucre double ; the outer forming a cup. 



82. TETRAGONOTHECA. Outer involucre 4-leaved. Achenia obovoid. Pappus none. 



*- - Involucre of one or more rows of separate scales. 

 33. ECLIPTA. Receptacle flat ; its chaff bristle-shaped. Pappus obsolete or none. 



84. BORRICHIA. Receptacle flat, its chaff scale-like and rigid. Pappus an obscure crown. 



85. HELIOPSIS. Receptacle conical ; its chaff linear. Pappus none or a mere border. 



* * Rays sterile (either entirely neutral or with an imperfect style), or occasionally none; 



achenia 4-angular or flattened laterally, i. e. their edges directed inwards and outwards, th 



chaff of the receptacle embracing their outer edge. 



t Receptacle elevated, conical or columnar. Pappus none or a short crown. 

 36. ECHINACEA. Rays (very long) pistillate, but sterile. Acheuia short, 4-sided. 

 87- RUDBECKIA. Rays neutral. Achenia 4-sided, flat at the top, marginless. 



88. LEPACHYS. Rays few, neutral. Acheuia flattened laterally and margined. 



- *- Receptacle flattish or conical Pappus chaffy or awued. 



89. IIELIANTHUS. Rays neutral. Achenia flattened, marginless. Pappus of 2 very decid- 



uous chaffy scales. 



40. ACTINOMERIS. Rays neutral, or sometimes none. Achenia flat, wing-margined, bearing 



2 persistent awns. 



* * Rays sterile, neutral : achenia obcompressed, i e flattened parallel with the scales of the 

 involucre, the faces looking inwards and outwards. Involucre double ; the outer spreading 

 and often foliaceous. Receptacle flat 



41. COREOPSIS. Pappus of 2 (or rarely more) scales, teeth, or awns, which are naked or 



barbed upwards, sometimes obsolete or a crown. 

 42 B1DENS. Pappus of 2 or more rigid and persistent downwardly barbed awns. 



* * * * Rays pistillate or fertile (rarely none) : achenia laterally flattened, 2-awned. 

 43. VERBESINA. Rays few and small. Receptacle convex. Achenia sometimes winged. 



Subtribe 3. TAGETIKK.S. Heads commonly radiate ; the rays ligulate ; the disk-flowers all 

 perfect and fertile. Receptacle naked, flat. Scales of the involucre united into a cup. 

 Pappus various. Herbage strong-scented (as in Tagetes of the gardens), being dotted 

 with large pellucid glands containing a volatile oil. 



44 DYSODIA. Pappus a row of chaffy scales dissected into many bristles 



Subtribe 4 HELENIEJB. Heads radiate or sometimes discoid; the disk-flowers perfwt. 

 Papp is of several chaffy scales. Anthers tailless. 



* Receptacle naked (not chaffy nor honeycombed). 



45 IIYMEK DPAPPUS. Rays none. Receptacle flat. Scales of the involucre colored. 



46. HELEN";UM Rays pistillate, 3- 5-cleft. Receptacle elevated. Involucre small, reflVxed 



47. LEPTOPODA. Rays neutral or sterile : otherwise as No 4G. 



* * Receptacle deeply pitted, like honeycomb. 



48. BALDWI NIA. Rays numerous, neutral. Involucre imbricated. 



1G 



