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 Add this item to the list   Merulius lacrymans Jacq. ex Fries
Page number:344 
Description type:Culture description 
Description:Merulius lacrymans Jacq. ex Fries
Cultural characters: (PI. V, Figs. 14, 15; Pl. VI, Figs. 48 to 50).
Growth characters. Growth slow, plates covered in five to six weeks. Advancing zone even or with fans of mycelium extending along edge of Petri dish in advance of mat proper, and then growing in to meet advancing periphery, raised aerial mycelium extending to limit of growth. Mat white at first then developing patches of "barium yellow" (8.0Y8.0/ y 6.5), "citron yellow" (7.0Y8.0/7.5), and "strontian yellow" (7.0Y8.3/9.0) (three weeks) to "Isabella color" (1.0Y5.5/4.3) (five weeks), slightly raised, silky then cottony-woolly, with small strands radiating from inoculum over surface of mat and expanding in fan-like arrangement at margin, or with strands grown up sides of Petri dish and over inner surface of cover. Reverse unchanged. Odor strong. On gallic and tannic acid agars no diffusion zones, diameter of colony 1.5-2.0 cm. on gallic acid agar, no growth on tannic acid agar.
Hyphal characters. Advancing zone: hyphae nodose-septate, 4.5-6.0 µm diameter. Aerial mycelium: hyphae as in advancing zone, 3.0-7.5 µm diameter. Submerged mycelium: (a) hyphae as in advancing zone, but usually narrower, 2.2-3.5 µm diameter; (b) crystals numerous, octahedral.
Type of rot: brown cubical rot of coniferous wood.
Descriptions of cultural characters: Badcock (3), Cartwright and Findlay (51, 52, 54, 56), Edgecombe (69), Humphrey and Siggers (92).
The foregoing description of Merulius lacrymans is based on only one culture, 8787, which grew as described when first examined in 1939, but which had changed when re-examined in 1942. At the later date it resembled the other cultures of M. lacrymans in the collection, all of which had reverted to the haploid condition, characterized by a very slow rate of growth, the radius of the colony being 2.0 cm. or less in six weeks, by the absence of clamp connections on all the hyphae, and by the production of numerous oidia. Cartwright and Findlay (54) quote Falck as having observed a similar change in old cultures of this species, "especially if the culture had been kept for long periods at a temperature above the optimum". The species is included in both the white and colored sections of the key, although the colors are probably always sufficiently deep to warrant its inclusion in the latter group only. Among the colored forms no other species has a key pattern identical with that for M. lacrymans. If it is considered as belonging to the white group, with nodose-septate hyphae, then it falls with several other species, from which M. lacrymans should be readily separable by reason of its consistent production of vivid yellow patches of mycelium and by its plumose growth. The haploid strain, whether taken as white or colored, stands alone in the key.

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