180 COMPOSITE FAlin^T. 



* # Pappus of naked, rough or shorUbarhed bristles, or none. 



I- Filaments of the stamem united into a tube. Leaves white-variegated. 



3. SILYBUM. Scales of the involucre willi the upper part leaf-like an4 spread- 

 ing, spiny. Receptacle beset with bristles. Akenes flattened: pappus of 

 miiny rather short and rigid' bristles minutely bearded on their edges. 



•) — \- Filaments separate. 



i. ONOPORDON. Heads and flowers as in true Thistles, No. 2. Receptacle naked 

 and honeycombed. Akenes 4-angIed, wrinkled: pappus of many slender 

 bristles united at base into a horny ring. Stems strongly leaf-winged. 



6. LAPPA. Scales of the globular involucre abruptly tipped with a spreading 

 slender awl-shaped appendage, mostly hooked at its point. Receptacle bristly. 

 Akenes flattened, wruikled : pappus of many short and rough bristles, their 

 bases not united, deciduous. Leaves and stAlks not prickly. 



6. CARTHAMUS. Outer scales of the involucre leaf-like and spreading, middle 



ones with ovate appendage frmged with spiny teeth or little spines, innermost 

 entire and sharp-pointed. Receptacle beset with linear chaff. Akenes very 

 smooth, 4-ribbed : pappus none. Leaves with rigid or short spiny teeth. 



7. CNICUS and 8. CEISTAUREA; see next division.- 



§ 2. Thistle-like or Scabious-like, with many-ranked imbricated scales to the involucre, 

 many-jiowers, and the two branches of the style united into one body almost or 

 quite to the tip, as ii). § 1 ; 6m( the outer flowers of the head differenl from llie 

 rest and sterile,.except in a few species of Centaurea. Receptacle beset with 

 bristles. 



7. CNICUS. Outer flowers smaller than the rest, slender-tubular, sterile. Scales 



of the invotaoro tipped with a long spine-like appendage, which is spiny-fringed 

 down the sides. AKcnes short-c,pindrical, many-ribbed and gi-ooved, crowned 

 with 10 short and horny teeth, within which is a pappus of 10 long and rigid 

 and 10 short naked bristles. Leaves prickly-toothed. 



8. CP^NTAUREA. .Outer flowers sterile and witli corolla larger than the rest, 



often funnel-shaped and with long sometimes irregular lobes, forming a kind 

 of false ray ; but these are wanting in a few species. Involucre various, but 

 the scales commonly with fringed, sometimes witli spiny tips. Akenes flat or 

 flattish : pappus of several or many bristles or naiTow scales, or none. 



§ 3. Bur-like or achenium-like In the fi-uit, which is a completely closed involucre 

 containing only .one or two flowers,<. consisting of a pistil only, with barely a 

 rudiment of corolla, therefore very different from most plants of the family i 

 but the staminate flowers are sevei'ol and m a flat or top-shaped involucre. 

 Heads therefore momBcious, or rarely dioecious: no pappus. Coarse and 

 homely weeds. 



S. XANTHIUM. Heads of staminate flowers in short racemes or spikes, their 

 involucre of several scales in one row : fertile flowers below them, clustered 

 in the axils, two together in a 2-cellod hooked-prickly bnr. 



10. AJIBROSIA. Heads of staminate flowers in racemes or spikes terminating the 



stem or branches, their involucre of several ^scales united in flattish or top- 

 shaped cup; fertile flowers clustered below the staminate, only one enclosed 

 in each small achenium-like involucre, which is naked, or with a few tubercles 

 or strong points near the top in a single row. 



§ 4. Plants not thistle-like nor bur-like. 



« Two kinds of flowers in the same head, the outer ones ivith pistils only. 



*-J?app)is^oneor,aminuieborderorcup: no chaff among theflowers: scales of the 

 involucre dry, often with scarious margins, imbricated. Sitter-aromatic or 

 rattier acrid; plants. 



11. TANACETUM. Heads of many yellow flowers ; the marginal ones with pistil 



only and a 3-6-toothed corolla. Akenes angled or ribbed, with a flat top, 

 crowned with a cup-like toothed or lobod pappus. Very strong-scented 

 herbs, with heads in a corymb. 



12. ARTEMISIA. Heads small, of few or many yellow or dull purplish flowers, 



some of the marginal Ones pistillate and foVtile, the others perfect, but some- 

 times not maturing the ovary. Akenes obovate or club-shaped, small at the 

 top, destitute of pappus. Bitter-aromatic, and sti-ong-sceuted plants, with 

 heads in panicles. 



