278 COMMON WEEDS 



and one or two western counties. It is an upright 

 perennial 2 feet or so in height, with deeply cut leaves, 

 and tall spikes of dark blue flowers, about an inch in 

 diameter, placed on upright downy stalks. The upper 

 sepal of the blue calyx is in the form of a hood or 

 cowl, hence the common name. The rootstock is 

 spindle-shaped. Flowering takes place from July to 

 September. 



Although the whole plant (Fig. 77) is very poisonous, 

 its virulence depends to some extent upon the age of the 

 plant and the climate in which it is grown. The leaves 

 are the least poisonous, the seeds more so, and the 

 root the most deadly. The toxic principle is the alkaloid 

 Aconitine. Drying removes a part of the poison, and 

 boiling removes most of it, as it is soluble in boiling 

 water (Cornevin). Medical works record many examples 

 of human poisoning, particularly in cases where its root 

 has been mistaken for horse-radish ; this mistake should 

 rarely occur, as the Aconite root is a conical tap-root, 

 tapering to a point, while that of the horse-radish is 

 cylindrical, and possesses a characteristic pungent 

 odour. The plant is generally avoided by live stock, 

 but poisoning of horses, cattle, sheep, and pigs have 

 been recorded (Cornevin). Linnaeus also says that it 

 is fatal to cows and goats when they eat it fresh, but 

 mentions that when dried it does no harm to horses. 



Buttercups (Ranunculus sp.). Several species of 

 Buttercups are of a poisonous character, containing an 

 acrid juice. All bear yellow flowers of varying sizes. 

 The toxic principle, however, is volatile, and easily 

 destroyed by boiling or drying; in hay, therefore, 

 Buttercups may be considered harmless, and are readily 

 eaten by stock, forming a nourishing food. Butter- 

 cups, however, may well be replaced in pastures by 

 more useful plants. (See also p. 152.) 



