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 tOcadstools. There are about a thousand British species 

 of these toadstools, or Agaricaceae, as the mycologists have 

 it, a group distinguislied 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 



^ 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 cles cham- 

 qngnons, 1791, plate 377) calls it Ag. annularius, and J. Sowerby (English 

 Fungi, vol. i, 1797, plate 101) Ag. siipitis. Fries (Si/stema 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 ]ierHists as an aniuilus, by which points the section is 

 distinguished from other whito-spored agarics. .Saccardo (/bV/Z/of/c Fmujurnm, 

 vol. V, ]). 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) 8acc. Innumerable figures of the fungus have been ])ublishod, 

 of which Vahl's. though uncolourcd, is one of the best. The Flora Batuva 

 contains two figures, viz. vol. x (1849), plate 775, and vol. xi (1853). 

 plate 815, the latter under the name Ag. mutahilis. Cooke's coloured 

 drawing {llUislrations of British Fungi, vol. i, plate 32) is not (|uile 

 characteristic. 



