COMPOSITE. (COMPOSITE FAMILY.) 219 



Subtribe 3. Bacchariclerc & Tarcb.onaiitb.ece. Flowers of the head all tubu- 

 lar, either dioecious or monoecious, namely, the staminate and pistillate flowers either in 

 different heads on distinct plants, or in the same head. Corolla of the pistillate fertile flow- 

 ers a very slender tube sheathing the style, and truncate at the summit. 



23. Plucbea. Heads containing a few perfect but sterile flowers in the centre, and many 



pistillate fertile ones around them. Anthers tailed at the base. Pappus capillary. 



24. liaccharis. Heads dioecious, some all pistillate, others all staminate, on different plants. 



Anthers tailless. Pappus capillary. 



Tribe IV. SENECIOXIDE.E. Heads various. Branches of the style in the fertile 

 flowers linear, thickish or convex externally, flat internally, hairy or pencil-tufted at the 

 apex (where the stiginatic lines terminate abruptly), and either truncate, or continued be- 

 yond into a bristly-hairy appendage. Leaves either opposite or alternate. 



Subtribe 1. Melampodinere. Flowers none of them truly perfect, but either stam- 

 inate or pistillate ; the two sorts either in the same or in different heads. Anthers tailless. 

 Pappus, if any, never of bristles. 



* Heads containing two kinds of flowers, the marginal ones pistillate, the central and tubular 



staminate flowers having a style, but always sterile. 

 - Fertile flowers with a ligulate corolla (rarely wanting in No. 25) : receptacle chaffy. 



25. Polymnia. Achenia thick and turgid, roundish. Pappus none. 



26. Cbr y sogoiium. Achenia flattish. Pappus a one-sided 2 - 3-toothed chaffy crown. 



27. Slip Ilium. Achenia flat, wing-margined, numerous in several rows: rays deciduous. 



28. Parthenium. Achenia flat, slightly margined : rays very short, persistent. 



-i- +- Fertile flowers with tubular or no corolla : no pappus. 



29. Iva. Achenia short and thick : receptacle with narrow chaff. 



57. Artemisia, in part. Achenia short and small : receptacle naked. 



11. Aclenocaulon. Achenia elongated, bearing stalked glands : receptacle naked. 



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



the same plant ; the pistillate only 1 or 2. in a closed involucre resembling an achenium or 

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



30. Ambrosia. Fertile involucre (fruit) small, 1-flowered, pointed and often tubercled. 



31. Xaiitliium. Fertile involucre (fruit) an oblong prickly bur, 2-celled, 2-flowered. 



Subtribe . Heliaii there. Heads radiate, or rarely discoid ; the rays ligulate, the disk- 

 flowers all perfect and fertile. Receptacle chaffy. 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-sided, slightly if at all flattened. 

 +- Involucre double ; the outer forming a cup. 



32. Tetragoiiotheca. 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. 



34. Borrichia. 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 ; ache- 



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

 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. Achenia short, 4-sided. 



37. Rudbecliia. Rays neutral. Achenia 4-sided, flat at the top, margiuless. 



38. Lepachys. Rays few, neutral. Achenia flattened laterally and margined. 



t- - Receptacle flattish or conical. Pappus chaffy or awned. 



39. Heliaiithus. Achenia flattened, marginless. Pappus of 2 very deciduous chaffy scales. 



40. Actinomeris. Achenia very flat, whig-margined, bearing 2 persistent awns. 



