Jan., 1919] Effects of the Eruption on Vegetation 195 



PLANTS WHICH LAY DORMANT FOR THREE YEARS. 



At first it was supposed that such recoveries of buried 

 herbage could occur only when it was exhumed soon after the 

 eruption, for it did not seem possible that ptants could sur- 

 vive burial for many months. But the observations of 1916 

 showed that this supposition was incorrect, for it was found 

 that in many places where the ash had lain undisturbed for 

 three years, until removed by the great flood of July 1915, 

 plants from the old roots had come up in all their original 

 vigor, forming in some places a rank and thrifty growth. (See 

 pictures opposite). When first observed, an effort was made 

 to interpret these patches in some other way than as sur- 

 vivals of such prolonged burial. It was first thought that 

 the areas must have been uncovered at an earlier date, for it 

 appeared incredible that they could have withstood a burial 

 of three years. But some of the areas were so associated 

 with high water marks many feet above the valley, that could 

 only have been made by the great flood, the date of which was 

 known, that the duration of the period of burial became a 

 certainty. It was then thought that the rich soil exposed 

 by the flood might have served simply as a favorable sub- 

 stratum on which wind distributed seeds had started, while 

 they failed on the adjacent banks of ash. But this hypoth- 

 esis was rendered untenable when it was observed that this 

 new growth appeared only in places where the original surface 

 of the ground had been left undisturbed by the flood waters. 

 Wherever the wash had been stronger, so as to carry off not only 

 the ash layer but also the surface soil with its included seeds 

 and remnants of vegetation, the bared areas, although as 

 rich as the surface soil, remained for the time, practically barren. 



The condition of the plants themselves was more positive 

 evidence, however, for it admitted of only one interpretation. 

 The new growth could be traced in most cases directly back 

 to the old stocks grown before the eruption. Associated 

 with these were, in many instances, the much weathered 

 remains of the growth before the eruption, but no remains 

 of growth of intervening years, such as would undoubtedly 

 have been present had any shoots appeared in those years, 

 were noticed. No plants were found which showed any indi- 

 cation of growth for several years back. 



