CHAPTER VIII 
ARMILLARIA MELLEA, THE HONEY FUNGUS 
General. Microscopic details of the fructification, Rhizomorphs. 
Effect on the host. The black line and resin flow. ‘The method of infection. 
Means of prevention. 
Armillaria mellea, (Vahl) Sace.,’ belongs to the large group 
of toadstools. There are about a thousand British species 
of these toadstools, or Agaricaceae, as the mycologists have 
it, a group distinguished from the rest of the higher fungi by 
having gills running radially on the under-surface, as in the 
mushroom ; and the very large majority of them are purely 
saprophytic, living either on the humus in the soil or on 
decaying timber or leaves. But a very few can also live 
parasitically, deriving their nutriment from the tissues of 
the host plants, and thereby causing them damage which 
may be more or less fatal. Of these Armillaria mellea is by 
far the most destructive. Indeed more trees die, in Europe 
at any rate, from attack by this fungus than through any 
1 The name Agaricus melleus dates back to 1777, and is apparently due 
to’ Vahl (Florae Danicae, fasc. 12, plate 1013). No doubt the specific 
name refers to the honey-coloured pileus. Bulliard (Histoire des cham- 
pignons, 1791, plate 377) calls it Ag. annularius, and J. Sowerby (English 
Fungi, vol. i, 1797, plate 101) Ag. stipitis. Fries (Systema Mycologicum, 
1821, vol. i, p. 26) fixes Vahl’s name, and places the species in his section 
Armillaria (L. armilla, a ring), characterized by its clothed stipe and 
partial veil which persists as an annulus, by which points the section is 
distinguished from other white-spored agarics. Saccardo(Sylloge Fungorum, 
vol. v, p. 80) was apparently the first to raise Armillaria to generic rank 
as applied to this species, so that the full title of the fungus is Armillaria 
mellea, (Vahl) Sacc. Innumerable figures of the fungus have been published, 
of which Vahl’s, though uncoloured, is one of the best. The Flora Batava 
contains two figures, viz. vol. x (1849), plate 775, and vol. xi (1853), 
plate 815, the latter under the name Ag. mutabilis. Cooke’s coloured 
drawing (Jilustrations of British Fungi, vol. i, plate 32) is not quite 
characteristic. 
