366 BOTANICAL GAZETTE [DECEMBER 
Vaccinium macrocarpon.—Where the prostrate stems of the 
cranberry come in contact with the moist peat, numerous short 
adventitious roots appear growing diagonally downward or almost 
horizontal. As the peat forms above and the roots and stems are 
weighed down to the water level, they die at the surface of the 
water. This species, growing with Aspidium Thelypleris, forms a 
tough woody network over a considerable part of this bog. 
Menyanthes trifoliata.—The rhizome of this plant assumes an 
approximately horizontal position from 3 to 9 cm. deep, while the 
roots may either be horizontal or vertical. The roots were found 
as much as 12cm. deep. They were few in number and compara- 
tively short but much branched. 
Eupatorium perfoliatum.—The base of the stem of this species 
assumes an approximately horizontal position near the soil surface 
Fic. 6.—Lathyrus palustris, map of rhizome system: L, living ena A, 
aerial stems; D, dead rhizome tips; solid black lines, living rhizomes; depth 6 
and the roots grow almost horizontally from this. In the bog the 
roots were found to reach a depth of 4-6 cm., while in mineral 
soil where the water table was much lower they reached down to 
depths of 5-10 cm. 
It should be noted that a very high percentage of all the living 
plant tissue in the bogs studied is above the water level. The 
part above water usually consists of a mat about 6 cm. thick, made 
of a coarse feltlike tangle of living roots and rhizomes largely of 
Aspidium, Carex, Vaccinium, and Menyanthes, and often a dense 
growth of Sphagnum. It is difficult to penetrate this tough mat, 
while just below the water level a sharp contrast appears. Here a 
fibrous, light brown peat is found in which the dead parts of these 
same species can often be recognized to considerable depths. 
_ Almost the only living parts encountered are occasional roots oF 
rhizomes of Typha, Sagittaria, Scirpus, or Eriophorum. 
