Lactarius repraesentaneus namely repraesentins B and C. These compounds were shown to promote the radicle elongation of lettuce seedlings by 136%, 118% and 184% at 67 ppm, respectively. Other compounds reported in 2006 are repraesentins D, E, and F. Repraesentin E showed the strongest growth promotion activity, 164% at 3.6 µm, of the three compounds toward the radicle elongation of lettuce seedlings. Lactarius repraesentaneus Lactarius repraesentaneus, commonly known as the northern bearded milkcap, the northern milkcap, or the purple-staining milkcap, is a species of fungus in the Russulaceae family. It has a northerly distribution, and is found in temperate regions of North
Lactarius repraesentaneus uvidus", "L. luridis", "L. psammicola", and "L. speciosus". The mushroom is commonly known as the "northern bearded milkcap", the "northern milkcap", or the "purple-staining milkcap". The specific epithet "repraesentaneus" is Latin for "well-represented". The cap of "L. repraesentaneus" is wide, convex to broadly funnel-shaped. The margin (the edge of the cap) is conspicuously bearded on young specimens. The cap surface is faintly zoned to azonate, with a thin layer of matted fibers, often becoming scurfy with age. It is dry to somewhat sticky, light yellow to orange-yellow, sometimes with rusty tints when older. The attachment of the gills to the