Page 146 - Ultimate Visual Dictionary (DK)

PLANTS

Pollination REPRODUCTIVE STRUCTURES IN
WIND-POLLINATED PLANT
Sweet chestnut
(Castanea saliva)
POLLINATION IS THE TRANSFER OF POLLEN (which contains
the male sex cells) from an anther (part of the male Flower bud Male
reproductive organ) to a stigma (part of the female Prominent stigma flower
reproductive organ). This process precedes fertilization protrudes from flower
(see pp. 146-147). Pollination may occur within the same Female
flower (self-pollination), or between flowers on separate flower
Peduncle
plants of the same species (cross-pollination). Part of male (inflorescence
Petiole catkin
In most plants, pollination is carried out either stalk)
(leaf stalk) (inflorescence
by insects (entomophilous pollination) or by the adapted for
wind (anemophilous pollination). Less commonly, Bract wind Filament
(leaflike pollination)
birds, bats, or water are the agents of pollination.
structure)
Insect-pollinated flowers are typically brightly
colored, scented, and produce Peduncle Anther
(inflorescence
nectar, on which insects stalk)
feed. Such flowers also Stigma
FEMALE MALE
tend to have patterns that
are visible only in ultraviolet REPRODUCTIVE STRUCTURES IN
INSECT-POLLINATED PLANTS
light, which many insects can
see but which humans cannot.
Endothecium
These features attract insects, (pollen sac wall)
which become covered with the
Style
sticky or hooked pollen grains
Pollen
when they visit one flower, Dehisced grain
and then transfer the pollen (split open)
pollen sac Anther
to the next flower they visit. Stamen
Wind-pollinated flowers are Filament
generally small, relatively
inconspicuous, and unscented. Boundary between
They produce large quantities two fused carpels
of light pollen grains that are (each carpel
consists of a stigma,
easily blown by the wind to style, and ovary)
other flowers. Calyx
Ovary (whorl of
sepals)
MICROGRAPHS OF MICROGRAPH OF CARPELS (FEMALE ORGANS) MICROGRAPH OF STAMENS (MALE ORGANS)
POLLEN GRAINS Yellow-wort Common centaury
Exine (outer coat of pollen (Blackstonia perfoliata) (Centaurium erythraea)
grain) Colpus Colpus
(furrow-shaped Exine
(furrow-shaped
aperture) (outer aperture)
coat of
pollen Exine
grain) (outer
coat of
pollen
Pore grain)
Exine Baculum
Pore (outer coat of (rod-shaped Equatorial
pollen grain) structure) furrow
EUROPEAN FIELD ELM JUSTICIA AUREA MEADOW CRANESBILL BOX-LEAVED MILKWORT
(Ulmus minor) (Geranium pratense) (Polygala chamaebuxus)
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