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laeobotany and Palynology, 2009,
156(1-2): 79-89 4 图 版 .
The morphology and ultrastructure of
some dispersed pollen grains from the
Permian of the Russian Platform were
studied using light microscopy (LM),
scanning electron microscopy (SEM)
and transmission electron microscopy
(TEM). Although being morphologically
similar in LM (more or less circular in
polar view with reticulate structure),
these pollen grains demonstrate strong
differences when studied under SEM
and TEM, showing that they correspond
to two different pollen taxa. The first
one exhibits under SEM a coarser reticulum
over the poles of the pollen grain
and a finer peripheral reticulum. The ectexine
includes a perforated tectum,
spongy infratectum with rather regular
short partitions, and a supposed foot
layer. The thick inner layer (supposed
endexine) appears nearly homogeneous,
but in places lamellate structures are distinguishable
suggesting that this layer
was originally lamellate. Such pollen
grains may be identified as Reticulatina
microreticulata. The second pool of
specimens was assigned to
Samoilovitchisaccites turboreticulatus.
The pollen grains of S. turboreticulatus
demonstrate a continuous tectum completely
covering the underlying exinal
layers; under SEM these pollen grains
appear nearly smooth. Differing in ectexine
ultrastructure, they are similar to
Reticulatina in the ultrastructure of the
innermost layer. Although both taxa are
of gymnospermous (pinopsid) affinity,
the similarity between the surface of Reticulatina
exine and that of Cretaceous
angiosperm pollen is fascinating.
2010010062
三 叠 纪 苏 铁 Delemaya spinulosa 的 花
粉 及 其 在 苏 铁 演 化 上 的 意 义 = Pollen
of the Triassic cycad Delemaya spinulosa
and implications on cycad evolution.
( 英 文 ). Schwendemann A B; Taylor T N;
Taylor E L. Review of Palaeobotany and
Palynology, 2009, 156(1-2): 98-103 1 图
版 .
The Cycadales are an order of gymnosperms
that represent one of the oldest
lineages of seed plants. Cycads are
thought to have originated in the Carboniferous,
and subsequently diversified
and geographically expanded throughout
the Mesozoic. Despite the geologic diversity
of the group, the evolutionary
history of cycads remains unresolved.
To a large degree this is because the
leaves of cycads and various other fossil
groups (e.g., pteridosperms and Bennettitales)
are morphologically similar.
To date there are relatively few fossil
cycad reproductive structures. Several
are known from the Permian of China,
but these compression specimens provide
little detailed information useful in
tracing the evolution of cycad cone
morphology and anatomy. A permineralized
cycad pollen cone from the Triassic
of Antarctica, Delemaya spinulosa, contains
in situ pollen. The objective of the
current study is to further elaborate the
structure of the pollen grains in this species,
with particular emphasis directed at
the structure and organization of the pollen
wall. The elliptical shape, monosulcate
aperture, and small size of the pollen
grains are like those of extant Cycadales.
The exine, although originally
described as homogenous, appears to
possess an alveolar organization. Pollen
and cone features are compared to those
in extant Cycadales.
2010010063
木 贼 的 系 统 发 生 及 演 化 : 来 自 孢 子 外
壁 结 构 的 证 据 = Phylogeny and evolution
of the horsetails: Evidence from
spore wall ultrastructure. ( 英 文 ). Grauvogel-Stamm
L; Lugardon B. Review of
Palaeobotany and Palynology, 2009,
156(1-2): 116-129 4 图 版 .
A new comparative TEM study of the
ultrastructure of the spores of the Carboniferous
genus Calamites with those
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