372 BOTANICAL GAZETTE [DECEMBER 
Discussion 
A comparison of the action of the roots of seedlings under 
experimental control with observations in the field shows that there 
are four general types of behavior of subterranean organs in these 
bogs. 
1. The roots and rhizomes assume an approximately horizontal 
position above the water table. Typical forms are Aspidium 
Thelypteris, Picea excelsa, Larix laricina (fig. 2), Carex filiformis, 
Pogonia ophioglossoides, Potentilla palustris, Lathyrus palustris, and 
Vaccinium macrocar pon. 
2. The tap roots of the seedlings die at the water surface and 
horizontal laterals appear above. Examples are Pinus Strobus 
and Abies balsamea. 
3. All underground parts are approximately vertical and die 
near the water surface, usually with non-horizontal laterals or 
adventitious roots appearing above, as in Sphagnum, Calopogon 
pulchellus, Sarracenia purpurea (fig. 5), and Drosera rotundifolia. 
4. The rhizomes and roots are able to grow under water. 
Important species are Typha latifolia, Sagittaria latifolia, Scirpus 
validus, Eriophorum, Betula pumila, and Decodon verticillatus. 
While doubtless there are many factors influencing the location 
of roots and rhizomes in bog soils, it becomes evident that the 
two most potent are hereditary tendencies and water level. Rhi- 
zomes of certain plants, such as Typha, assume a depth apparently 
determined by heredity, which places them below the surface 
of the water. Such plants as can readily endure submergence are 
able to persist in the bog unless other factors interfere. Obligate 
deep-rooted plants which are intolerant of submergence are elimi- 
nated by water from this flora. Rhizomes of certain other species, 
as for example Aspidium Thelypteris, are in all cases superficial, 
thus permitting their development above water. On the other 
hand, the roots especially seem to respond rather readily to the 
water surface. A number of species have only shallow roots 
where the water table is high, but deeper ones in most peat or moist 
mineral soil. This was found to be especially well illustrated by 
Aspidium Thelypteris, Pinus Strobus, and Acer rubrum; hence it 
is apparently not the quality of the soil but the presence of water 
