34. . ComposiTaz. 
to seed freely on his land, and infect that of his neighbours, can be said 
to have used reasonable exertions to destroy such thistles. Further, thistles 
that have begun to flower, if cut and burnt at once, or piled in ‘heaps and 
covered with quicklime, will set free very little seed as compared with the 
same plants left standing. Even when fruiting is active, the plants can 
be cut on a rainy day without seed being spread, but in this case they 
must be handled wet, and either buried or covered with quicklime. Further- 
more, fruiting plants, when dense, can be sprayed with kerosene, and burnt 
off standing, with little or no escape of seed, and without danger if a safety 
zone is cleared around the infested patch, and the burning done in calm 
weather. 
Key to the Common or Proclaimed True, Star, and Burr Thuistles. 
t. (a) Florets in the head all equal and tubular. Seed-like achenes, with 
a long. pappus of simple or branched hairs. Leaves usually very prickly. 
—True Thistles. (2). 
(8) Outer florets usually larger and neuter. Pappus shorter than the 
achenes, and usually of simple hairs or scales, or absent. Leaves rarely 
prickly, but bracts of the heads fringed or very prickly.—Star Thistle. (5). 
(c) Burred fruits, leaves not prickly, but radiating spines on the stem 
among them, and the fruits.—Burweed (Vanthium spinosum, L.). 
True THISTLES. 
2. (a) Pappus of simple unbranched hairs ee See nan & 
(2) Pappus of feathery hairs oe ee as ae 
3. (2) A large, stout plant, the leaves variegated with white veins. 
the flower large, purple, and drooping.—Milk Thistle (Carduus Marianus, 
L.). 
(6) An equally tall (one to three or four feet), but more slender plant ; 
the stems winged ; the plant more or less cottony ; the heads smaller, nume- 
rous, and clustered, and with pink or white flowers.—Slender Thistle 
(Carduus pycnocephalus, Jacq.). 
(c) A still more slender plant, with heads of intermediate size, and the 
stem with narrow prickly wings from top to bottom. (Cardzius crispus, 
L.). 
4. (a) A stout biennial, leaves and bracts ending in stiff prickles, the 
flower heads few and long.—Spear Thistle (Carduus lanceolatus, L.). 
(b) A perennial, with a creeping root-stock ; very prickly leaves, and 
the bracts with numerous small prickly points; the flower heads small, 
numerous, and clustered.—Creeping or perennial Thistle (Carduus 
arvensis, L.). 
(c) The less common Scotch Thistle (Oxopordon acanthium, L.) is a 
large plant, with single large heads of purple flowers, winged and prickly 
stem, and the ovaries of the small, tubular flowers enclosed in small, scaly 
cups within the involucre of densely set small ,pointed green bracts. 
5. Star THISTLES, 
5. (@) Plants with prickly leaves and heads, the latter large, with 
yellow and occasionally purple flowers, and the achenes with a densely 
clustered pappus of narrow pointed scales.—Saffron Thistle (Kentrophyllum 
lanatum, D.C.). 
(6) Heads smaller, but spiny ; leaves not spiny ... ety ee. 1G 
