The vegetation at the ending of Carboniferous times was much affected by
the great changes in the earth’s surface which happened then. The
thrusting up of great mountain chains, the slow encroachment of
continental glaciers, and the other phenomena characterizing that period
could not but be reflected in the plant population. For one thing the
giant club mosses and horsetails were much reduced in extent and finally
disappeared, leaving only the immediate ancestors of our present-day
forms. _Cordaitales_ gave place to trees not unlike some of the modern
yew trees. True ferns as well as the cycadlike ferns with seeds appear
to have lived side by side with true cycads, which subsequently
supplanted their obvious cycadlike fern ancestors. There was an obvious
dwindling of ancient Carboniferous forms, some of which, however,
persisted in considerable numbers. Many other plants existed then, some
of which died out there, and some of which still survive in descendants,
particularly among our conifers and ferns. But there happened toward the
upper end of this period an event in the history of the plant kingdom so
dramatic, of such far-reaching results, that its appearance might be
likened to the overthrow of the Czar in Russian history or to the
downfall of the Kaiser in Germany. For with it dawned a new era for the
plant world, the effects of which we see all about us to-day.
Somewhere in the rock strata of this period we find the first
angiosperm, or plant that matures its seed in a closed ovary, and with
the origin of that habit there began such a development of plants of
this type that its impetus has not yet been lost. It is impossible to
tell at this distance from the origin of that first angiosperm from what
it developed, nor how many ages it may have existed before the accident
of its preservation as a fossil revealed its presence. It is certainly
not without significance that it bore conelike fruits, such as all its
associates and predecessors among flowering plants had done, but its
possession of large, showy petals is the first evidence of a flower
characteristic that was destined to make our present vegetation the
lovely thing it is. This exceedingly interesting plant was a _Magnolia_
(Figure 110), or so like our present plants of that genus as to be their
obvious ancestor. Somewhere here, too, must have arisen the insect
fertilization of flowers which we have seen to be such an important part
of flower economy at the present time. Most of this ancient magnolia’s
associates must have relied on wind pollination for seed production, as
many modern plants still do, but the origin of insect fertilization
appears to have come with the appearance of the first really
petaliferous flower.
[Illustration: FIG. 110.--COMMON LAUREL MAGNOLIA
(_Magnolia virginiana_)
The fossil record tells us that probably the first flowering plant was
some ancestor of magnolia.]
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