COMPOSITE. (COMPOSITE FAMILY.) 161 



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

 29 lYA. 1'istillate flowers 1-5 iu the margin. Achenia thickish. Pappus none. 



• * * Ileads of two sorts, one containing staminate, the other pistillate flowers, both borne on 

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

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



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



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



Subtribe 2. Heliantiie^. Ileads radiate, or rarely discoid ; the ray* ligulate, the disk- 

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

 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. 



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

 t- Involucre double ; the outer forming a cup. 



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



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



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



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

 35. 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, tho 

 chaff of the receptacle embracing their outer edge. 



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

 86 ECHINACEA. Rays (very long) pistillate, but sterile. Achenia short, 4-sided. 



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



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



*- +■ Receptacle flattish or conical Pappus chaffy or awned. 



89. HELIANTUUS. 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 ; tho 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. BIDENS. Pappus of 2 or more rigid and persistent downwardly barbed awns. 



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



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



Subtribe 3. Tagetinex. Ileads 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 Tagetcs 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. Helenie^. Heads radiate or sometimes discoid ; the disk-flowers perfwit. 

 Pappus of several chaffy scales. Anthers tailless 



* Receptacle naked (not chaffy nor honeycombed). 



45 HYMENOPAPPUS. Rays none. Receptacle flat Scales of the involucre colored. 



46. HELENIUM. Rays pistillate, 3 - 5-cleft Receptacle elevated. Involucre small, reflexed. 



47. LEPTOPODA. Rays neutral or sterile : otherwise as No 46. 



* * Receptacle deeply pitted, like honeycomb. 



48. BALDW1NIA. Rays numerous, neutral. Involucre imbricated. 



