Nov., 1890. 
PLANT MARCHES. 
249 
PLANT MARCHES. 
BY J. B. STONE, J.P., F.G.S., F.L.S. 
In following the story of the progression of plant life, from 
the rank vegetation of the Carboniferous period to the glorious 
flora of the present age, some remarkable facts are encountered, 
which not only invite the attention of botanical students, but 
are important guides in determining the broad outlines of 
geologic science. 
The more philosophical reasoning is applied, the more 
evident is it that botanical knowledge is needed to aid the 
solution of the many and unexpected problems which are con¬ 
stantly arising, when tracing the world’s history in its geo¬ 
logical records. It is especially useful, if not needful, to 
possess some knowledge of the causes which have influenced 
and directed the geological distribution of the flora of recent 
times, as the application of the same natural laws assists in 
determining phenomena occurring through series of geological 
epochs. 
For instance, certain types of plants—whose presentments 
are recorded in fossils—connote by their presence certain 
climatic conditions which, by analogy, we may pretty nearly 
determine, and in the prevailing presence or in the remark¬ 
able development of certain vegetable forms, temperature and 
chemical atmospheric conditions may be correctly assumed. 
As an illustration, the presence of fossil plants and their seeds 
embedded in the rocks of Arctic latitudes, whose surviving 
representatives require conditions of a temperate or hot 
climate to sustain life and permit them to fructify, would 
indicate climatic change and possibly something more, for it 
may also demonstrate an altogether different arrangement of 
land areas, if not of continents, with a consequent difference 
in the flow of tropical currents to the Poles. 
Among the more noteworthy effects of great geological 
changes, is the circumstance that the typical flora of any 
geological epoch practically ceased with the epoch ; either 
submergence of land, or some other equally destructive agency, 
swept away the main plant-life of the period, and such 
straggling survivors as fortuitous circumstances permitted to 
escape and perpetuate their race were singularly few. 
It is extremely rare to find any species continuing an exist¬ 
ence through more than one geological period, and the 
exceptions which reappear in a subsequent age, or have a still 
longer tenure of existence, possess more than an ordinary 
interest, and may be considered as being worthy of special 
attention, contributing, as they do, additional information as 
to existing conditions common to the respective periods. 
