[j.wuarv BOTANICAL GAZETTE 42 



furnishing protection and humus, is characteristic of the climax 

 forest. Unlike conifer needles, the leaves fuse during the winter 

 into a single tough layer averaging 2-5 mm. thick, thinnest in late 

 summer and thickest in late fall. Its base continually decomposes, 

 adding to the humus below. 



Twigs are always abundant on the forest floor; and since the 

 herbage is open they interfere little with it. Their fall is light and 

 they reach the ground soon, being smooth and slender and not 

 liable to catch. They are easily pushed aside by all plants. 

 Branches often remain on the tree for some time after death, but 

 combined action of basal rotting and weather eventually tears them 

 loose. Yet even then one may not fall, at times hanging by a strand 

 of cortex and alburnum that is often remarkably small, or it may 

 catch on the parent or a nearby tree at one of the crotches or lower 

 branches. Usually one large branch is found on every 3-10 sq. m. 

 Annual vegetation can be hurt for but one season, but perennial 

 aerial parts are injured permanently. 



The fallen trunk rots slowly, leaving a soil ridge and a narrow 

 lane for many years. Stumps rot as slowly into a low mound, but 

 hemlocks remain standing as giant stubs 10-20 m. tall with the 

 branches lost. Their wood rots until it cuts like putty, but the 

 bark will hold up for many years, being thick and tough, rich in 

 tannin, and not rotted by fungi or eaten by insects. Maples and 

 beeches rarely leave such stubs, except as the result of fungus en- 

 trance some distance up the trunk. Those that are left do not 

 stand long. 



Lichens are found sparingly on trunks above the sapling syn- 

 folium and on exposed trees. They are also seen on the larger 

 branches and are. more common on the maples and hemlocks, 

 because the beech affords poor foothold. A year after a big tree 

 falls, however, its bark is covered by a luxuriant and varied growth 

 of foliose lichens, in consonance with the removal of the substratum 

 from a xerophytic to a richly mesophytic environment. 



Mosses are not common on vertical trunks. Ferns are not seen 

 as epiphytes in this region, though not from lack of either individuals 

 or species. Both may be found growing on rotting stubs (not 

 hemlock). 



