Agriculture Reference
In-Depth Information
Propagationandlandscapeuse
A plant's manner of propagation will
determine its landscape use and how it should
be pruned. Plants can be propagated sexually
or asexually; that is, they can be grown from
seed, a product of sexual union (pollination)
between pollen (male cells) and ovules
(female cells), or grown asexually by cuttings,
grafting or budding, or from tissue culture.
of the same species, although there are
exceptions. Most plants have perfect flowers;
that is, they carry both male and female parts
in the same flower. They may need cross-
pollination from another of the same species
or can be self-pollinating/self-fertile.
Some plant species are
monoecious
.
This means that male flowers and female
flowers are produced separately, but both
on the one plant ('mono' meaning 'one').
Pumpkins, squash, sweet corn, hazels
and walnuts are all examples of this
(see Figure 2.12).
Asexual propagation results in plants that are
genetically identical, therefore they will
perform in a uniform manner given the same
growing conditions.
Seedgrownplants-sexualpropagation
As a result of sexual reproduction, seedlings
are as variable as we are. This has advantages
and disadvantages. In recreated natural
landscapes, genetic diversity is of primary
importance so only seed-grown plants should
be used. If an avenue of trees or a hedge is
being planned where uniformity of growth is
required, plant asexually propagated plants;
that is, clones.
Seedling-grown plants have a typical tap root
system that anchors them in the ground (see
Figure 1.3, page 3). In large woody plants
these root systems are easily damaged with
dire consequences, especially with eucalypt
species. Care must be taken when selecting
such plant material (see page 18) as the root-
to-shoot ratio is critical in the successful
establishment of seedling-grown large woody
plants.
Pollination
Pollination that results in seed/fruit
production can only occur between members
Figure 2.12
Corn is monoecious; the male flowers at the
top drop pollen on the cornsilk stigmas that lead to the
corn's ovaries below.
