文档介绍：第五章 植物器官的结构及组织分化
四、花
Flower
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The duckweeds (family Lemnaceae) are
the smallest flowering plan
周位花
上位花
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2、花被
花萼 Calyx
花冠 Corolla
萼片：由薄壁组织、维管系统及表皮层组成
Sepal 表皮层上有气孔和表皮毛
花瓣：由薄壁组织、维管系统及表皮层组成
Petal 表皮层细胞的垂周壁呈波纹状或内脊，
表皮层上有气孔和表皮毛
薄壁组织中可含有一些异细胞，成熟
花瓣中 有有色体或细胞液中有花青素
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3、雄蕊群
花药 Anther
花丝 Filament
4、雌蕊群
子房 Ovary
花柱 Style
柱头 Stigma
基本单位是心皮 Carpel
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Parts of a lily (Lilium henryi) flower.
(a) An intact flower. In some flowers,
such as lilies, the sepals and petals are
similar to one another, and the perianth
parts may then be referred to as tepals.
Note that the sepals are attached to the
receptacle below the petals.
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(b) A partly
dissected flower with two tepals and two
stamens removed to reveal the ovary.
The gynoecium consists of the ovary,
style, and stigma. The stamen consists of
the filament and anther. Note that the
sepals, petals, and stamens are attached
to the receptacle below the ovary, which
is made up, in the lily flower, of three
fused carpels. Such a flower is said to
be hypogynous.
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The wall of the pollen grain serves to
protect the male gametophyte on its often
lIozardous journey between the anther
and the stigma. The outer layer, or exine,
is composed chiefly of a substance known
ossporopollenin, which appears to be a
polymer composed chiefly of carotenoids.
The exine, which is remarkably tough
atld resistant, is often elaborately
~culptured.
The sculpturing of pollen grain walls
is very precise and distinctly different
from one species to another, as revealed
ill these scanning electron micrographs
of pollen grains. (a) Pollen grains of the
horse chestnut (Aesculus hippocasta-
num). The pore of each grain through
which a pollen tube may emerge is vis-
ible in the furrow. (b) Pollen grains of
a lily (Lilium longiflorum). (c) Detail
of the surface of a lily (L. longiflorum)
pollen grain. (d) Pollen grai