Fossil plants, Vol. 3 : $b A text-book for students of botany and geologySeward, A. C. (Albert Charles)
Science
Fossil plants, Vol. 3 : $b A text-book for students of botany and geology
Seward, A. C. (Albert Charles)
Paleobotany
_Wardia fertilis_ (White). Another example of a fern-like frond bearing
seeds is afforded by specimens from the Lower Pottsville series of
Virginia (correlated with the Millstone grit of British geologists)
described by Mr David White[456] as _Aneimites_ (_Wardia_) _fertilis_.
The compound fronds usually referred to the genus _Adiantides_ or
_Adiantites_[457] are characterised by cuneate pinnules with a thin
lamina and forked, slightly divergent veins (fig. 445, A, D). White
discards the name _Adiantides_ in favour of Dawson’s genus _Aneimites_
on the ground that Goeppert[458], who instituted the former term,
applied it in the first instance to leaves of _Ginkgo_ which he
identified as simple Fern fronds. In spite of this misapplication of
the name it has been constantly used and is well established. The
discovery of seeds is, however, a reason for the adoption of a new
generic name, and as White proposed _Wardia_ for the seeds it may
appropriately be extended to the fronds in place of the provisional
term _Aneimites_. The seeds which occur at the apices of slender
pedicels on pinnae bearing relatively small pinnules with a reduced
lamina (fig. 445, B, C) are rhomboidal in shape, 4·5 mm. long and 2·5
mm. broad. The bilaterally symmetrical seeds were probably enclosed,
as White suggests, in a fleshy integument which on pressure became
laterally extended as a wing-like border. In some of the seeds there
is an indication of a ‘slight collapse within the apex of the nutlet,’
which may mean the presence of a pollen-chamber; but while the
preservation is too imperfect to afford any decisive evidence as to
anatomical features, there is no reason to doubt the conclusion as to
the seed-nature of the organs described by White. Nothing is known of
the stem, though the opinion may be hazarded that _Wardia_ is a member
of the Medulloseae.
_Adiantites bellidulus_ Heer and _Lagenospermum Arberi_ Nathorst.
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