General Information: Easily recognised by the dull colours and purple reaction with alkali; there is no British species with which L. turpis can be mistaken. The purple reaction is similar to that found in the familiar school laboratory reagent litmus, for the compound found in L. turpis turns purple in alkali and reddens in acidic solutions. First discovered by Harley in 1893 this reaction marked the beginning of a whole series of chemical studies on the agarics which has led to the discovery of many unique compounds.
Illustrations: Hvass 214 (but too green); LH 213; NB 1133; WD 381.
General notes on the genus Lactarius
There is little doubt that the genus Russula and the genus Lactarius are closely related; in fact they stand aside from the other agarics in the very important character mentioned on [page 46]. In Europe the easiest distinction between the two genera is that members of the genus Lactarius exude a milk-like juice which may be white or variously coloured depending on the species involved (e.g. purple in L. uvidus (Fries) Fries, yellow in L. chrysorheus Fries). The cap, stem and frequently the gills are brittle and when broken liberate the milk-like liquid; when the fruit-body is dry, however, the presence of this liquid may be difficult to demonstrate. The spores have a blue-black ornamentation under the microscope when mounted in iodine, and although when in mass the colours are not as varied as those found in the genus Russula there is every likelihood that they will play an important role in the classification of the group in the future. The colour of the spore-print has been rather neglected, although the genus includes some rather unusual fungi.
Plate 8. Fleshy and milking fungi: Spores whitish and borne on gills
![[Larger illustration]](#467779198995390083_illo051lg.png.id-5567625970399804042.wrap-0.html.html){kind=link}
The odours of many species are very distinct and vary from the smell of coconut and spice to those of various flowers; an odour commonly met with is termed ‘oily rancid resembling butter which has become mouldy’; in early books it was described as being the smell of bed-bugs!
The majority of the species are undoubtedly mycorrhizal: thus L. torminosus is found with birch, L. deliciosus and L. rufus with conifers and L. quietus with oak. Brief notes are given on additional species:—