34 BULLETIN 802, U. S. DEPARTMENT OF AGRICULTURE. 
BOG- SHRUB TYPE. 
" Heath peat," " Reisertorf," " Heidetorf." 
Reddish to rusty brown wickerlike peat material, partly finely 
fibrous from rootlets, but with numerous small twigs forming a 
prominent proportion. The woody fragments are derived from roots, 
stems, and branches of various bog shrubs, mainly heaths; the mac- 
erated ground mass is more or less resinous. 
The type is often accompanied by a marked occurrence of highly 
ferruginous impurities either distributed through the mineral sub- 
soil as a hard impermeable layer or pan or in the form of bog iron 
on and near the surface. In coastal climates the bog shrubs show 
beneath the peat material a layer of leached-out whitish or gray 
sand of varying thickness; underlying it is a characteristic blackish 
or yellow to rusty brown iron-stained sand, which often contains 
much of the mineral material and organic colloidal complexes leached 
from the upper sandy layer. The soils when denuded of their 
surface covering of peat material appear to be unsuitable for ordi- 
nary farming practices unless well handled. Pans, however, are by 
no means confined to heath bogs; they often occur in forests and on 
certain marshy and cultivated sandy soils. 
The plant remains in heath peat are derived largely from bog 
shrubs, among which Andromeda sp. and Cassandra (Chamaedaphne) 
sp. are the most prominent of the ericaceous plants. Other genera, 
such as Ledum, Vaccinium, Myrica, and Kalmia, are less numerous in 
individuals and not so general in their distribution as to give rise to 
specific types of heath peat. In some of the sphagnum-cranberry bog 
meadows they are present in sufficient numbers to make a dense 
thicket, thus shading and even destroying the vegetation which 
covers the ground. The plants spread rapidly by means of long 
horizontal underground stems, from which arise at intervals erect 
leafy branches. 
Empetrum nigrum and Calhma vulgaris occur very rarely on bogs 
in the United States, but they are among the low evergreen heath 
shrubs in the bogs of Canada and occur generally on the bogs or 
high moors of northern European peat deposits. 
The chemical and other data cited in Tables I and II relate to 
heath types of peat on high moors. 
THE SWAMP GROUP OF PEAT MATERIALS. 
Types of peat material from coniferous trees and from deciduous 
shrub and tree stages of a vegetation series on a wet substratum with 
the ground-water table generally below the surface during part of 
the year, as in bog forests and pond swamps, or partially submerged, 
as in river and coastal swamps. 
