176 
THE PRINCIPLES OF BOTANY. 
Table of space occupied by Thistles. 
Diameter of leaves 
in inches. 
Musk Thistle 25 
Welted Thistle . . . . . 30 
Small flowered Thistle .... — 
Spear Thistle 40 
Woolly-headed Thistle .... 48 
Marsh Thistle 24 
Height of plant 
in flower. 
24 
38 - 
18 
36 
50 
30 
Nettles, too, take up room in the pasture and injure the hay. 
4. Poisoyious plants. — The most prominent of these will be 
the Colchicum autumnale — meadow saffron. The colchicum, 
in all its stages of development and every part of the plant, 
contains an active principle of very poisonous properties, 
which has been named by the chemist veratrine. The pre- 
sence of this renders it a very active medicine, and pharma- 
ceutical preparations are made from the corms, commonly 
called the roots, and from the seeds, but the flowers are pro- 
bably still more replete with the active principle, and conse- 
quently more poisonous than any other part of the plant. These 
medicinal qualities have for ages recommended coldhicum as 
a remedy for gout; but it is so powerful a medicine, and 
withal so uncertain in its effects, that these require the sedu- 
lous watching of the medical practitioner — facts that are 
mentioned only to show the powerful effects of colchicum on 
the human system. 
In the autumn we constantly hear of cases of cattle poison- 
ing by the colchicum, of which we shall furnish examples 
t when we come to speak of the history of the colchicum itself. 
At present it is only necessary to point out that fields much 
inhabited by this plant are rendered nearly useless for autumn 
depasturing on account of the legends regarding the injury 
they have occasioned to stock. 
5. Ill-fl av our ed plants are weeds in pasture, not because they 
merely occupy space to the exclusion of better, nor that they 
are ill-flavoured to the animals partaking of them — for it 
would seem that they are not so to the extent of preventing 
their being constantly eaten — but because such plants, espe- 
cially the 
Allium vineale — Crow garlic, 
„ ursinum — Hog 5 s garlic. 
Erysimum alliaria — J ack-by-the-hedge, 
impart a most disagreeable flavour to dairy produce, and are, 
therefore, highly objectionable in the pasture. 
All the plants named in the foregoing list, with many 
others not mentioned, can only be considered as weeds in 
