698 COMPOSITAK 
Stem hollow, much branched, 6 to 15 in. high. Leaves lance-shaped but 
deeply lobed on each side of the mid-rib (pinnatifid), the lobes toothed. 
Scales of the involucre blackish, almost always a few short ones at the 
base of the involucre. A weed in cultivated grounds and waste places. 
Aprli-Oct. 
8. §. sylvaticus, L. Woop GrounpsEL. Resembles No. 7, but heads are 
higher and involucre without the short scales at the base. Waste places, 
introduced. April-Sept. 
9. §. viscosus, L. Forrip GrounpseL. Resembles No. 7, but heads 
are much more slender, scales are not black-tipped and the whole plant is 
covered with a viscid ill-smelling covering of down. Introduced; waste 
places. July-Sept. 
so. ARCTIUM, L. 
Very coarse biennial weeds with large alternate leaves on leaf-stalks 
and with clustered heads of purple tubular flowers, the rounded involucre 
of many overlapping hooked scales, the heads forming a bur. Heads many 
flowered, all tubular. Receptacle bristly. 
1. A. Lappa, L. (Fig. 5, pl. 197.) Burpock. Stout, 1 to 4 ft. high 
or occasionally much exceeding this height. Leaves egg-shaped, 8 to 18 
in. long, often heart-shaped at base; margins not toothed. Bur often an 
in. in diameter, the bracts not cottony. A common large weed in waste 
places. 
Var. A. tomentosum, (Lam.) Schk. (Fig. 4, pl. 197.) Corrony Bur- 
pock. Resembles No. 1, but leaves more wavy at margins and the invyo- 
lucre densely cottony. 
2. A. minus, Schk. (Fig. 6, pl. 197.) Common Burpock. Similar 
to No. 1, but generally smaller and leaves firm and somewhat tapering 
at base, though the lower are heart-shaped. Involucre bracts not cottony. 
Heads about 2 in. in diameter. 
51. CARDUUS, L 
Erect branching herbs or in some species without stem, mostly biennial, 
with alternate, usually lance-shaped leaves which are without leaf-stalks, 
generally deeply lobed and armed with stiff, sharp, prickles. Heads 
usually large, many-flowered, the flowers all tubular, purple, yellow or 
rarely white. Involucre egg-shaped of many overlapping bracts, which are 
in many cases prickle-tipped, but sometimes unarmed. Receptacle flat 
or convex, bristly, Aigrette of several series of plumose hairs. 
Flowers yellow . J ee ee a eR eae Gc 
Flowers purple or white, 
Involucre bracts all prickle-tipped . . . . » » « «  €. lanceolares 
Outer bracts prickle-tipped, inner bracts unarmed, 
Leaves divided into narrow lance-shaped SERENE 
Leaves woolly beneath . .. . - « C. discolor 
Leaves green, both sides C. odoratus 
Leaves not divided into lance- shaped lobes, though they may 
HEWIODEGI ie) 4a. 4. e. Fee aces eee C. altissimus 
Involucre bracts not prickly. 
Leaves woolly beneath. 
Flower heads solitary « . » » «© «© =» « «© =» Gy stays 
Flower heads in groups. 
Flower stems with few or no leaves or prickles C. muticus 
Flower stems short, Jeafy and prickly . . . C. crispus 
Leaves not woolly .. » s W i. wv we 6 « « e GomGrmemees 
