COMPOSITiE. (composite FAMILY.) 181 



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

 29 XYA Pistillate flowers 1 - 6 in the margin.. Acheoia thickish. Pappus none. 



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

 the same plant ; the pistillate only 1-2, in a closed involucre resembhng au achenium or 

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



80. AMBROSIA. Fertile involucre (fruit) small, l-flowcred, pointed and often tuborcled. 



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



Subtribe 2. Heliahthe.!:. Heads radiate, or rarely discoid ; the rays ligulatc, the disk- 

 flowers all perfect and fertile. Receptacle chafly. Anthers blackish, tailless. Pappus 

 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-flided, slightly if at all flattened, 

 ■t- Involucre double ; the outer forming a cup. 



32. TETRAGONOTHECA. Outer involucre Cleaved. 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. 



34 BORRICHIA. Receptacle flat, its chaff scalc-Uke and rigid. Pappus an obscure crown. 



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



* * Rays sterile {either entirely neutral or ^vith an. imperfect style), or occasionally none; 

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

 chaff of the receptacle embracing their outer edge. 



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

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



37. 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. HELIANTHU3. Rays neutral. Achenia flattened, marginless. Pappus of 2 very decid- 



uous chaffy scales. 



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



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 axe naked or 



barbed upwards, sometimes obsolete or a crown. 

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



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



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



Subtribe 3- Tagetinejb. Heads commonly radiate ; the rays hgulate ; 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 volatUe oil. 



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



Subtribe 4 Helemea. Heads radiate or sometimes discoid ; the disk-flowers perfect. 

 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, reflexod. 



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



# * Receptacle deeply pitted, Uke honeycomb. 



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



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