plant which also known as vascular plant form a large group of plants that have xylem and phloem which make them able to
conduct photosynthesis. They reproduce either by spores, cones, or flowers. In this
higher plants group they have three different type which is gymnosperms mainly
the conifers and cycads then angiosperms or also known as flowering plant and
lastly the pteridophytes or ferns
such as clubmosses, and horsetails.
Firstly, gymnosperms is
derived from two Greek words: gymnos
which mean naked, and sperma, meaning
a seed. This naked seed which not contained within an ovary or fruit allowed
them to be directly fertilized by pollination.
It is develop on the surface of scales and leaves and then grow to form
cone or stalk. It have four major phyla which is phylum Pinophyta (Conifers), Cycadophyta (Cycads), Gingkgophyta (Gingko), and Gnetophyta (Gnetophytes).
Conifers, in the phylum Pinophyta, are the most numerous of the gymnosperms
because they are woody and with vascular tissue. It also have cone bearing
trees and shrubs. Conifers can be found mostly in the boreal
forests of the northern hemisphere. It is adapted to survive to
face cold weather by having downward facing branches that allowed snowfall. It also
have and specific biochemical properties that provide resistance to freezing. Conifers include pines, yews,
redwoods, spruces, firs and cedars. As they are in gymnosperms, they did not
produce flower, but they have cones holding the seed. The female cones have
outer scale that carry ovules which after fertilization become seed. The pollen
in male cones will moved by wind so called wind pollination. Even most of the
conifers are monoecious it also have dioecious plant which mean they are
separated male and female plants.
cycads in phylum Cycadophyta they are gymnosperms
because they have evergreen compound
leaves and dioecious where the
fertilization take place after male cones
produce pollen that is carried by wind to
female cones as they are separated plant. Typically they constitutes a
single, stout, cylindrical, woody trunk and a crown of large, hard and stiff, which
grow directly from the trunk in a rosette formation. There are only three
extant families within the cycads today which is Cycadaceae, Stangeriaceae
Next, Gingko is a genus of gymnosperm.
They are closest relatives to the cycads but they have different characteristic.
Apart from having naked seed, they have nice small fan-shaped leaves and higher
tree which is up to 160 feet but slender in shape. They able to face wind and
snow. They are also resistant to disease and insect damage. The seed and leaves
been used in medicine from the past till today in the entire world.
The gnetophyta are unique within the
gymnosperms because they have vessel which mostly
found in the angiosperms. The vessel is in the xylem which transport water. This
phylum have three families. They are Ephedraceae,
Gnetaceae, and Welwitschiaceae. Covering 70 species over three families,
the gnetophyta are morphologically variable,
including trees, shrubs, stumps, vines and creepers with leaf shapes ranging
from opposite, to whorled, scale-like and straplike. The Ephedra found in southwestern North America as they been adapt by
having tiny leaves. They produce spores in cone-like structures which the male
will disperse their spore and female will receive the spores. Gnetum found on tropical and humid
region. As a member of gymnosperms they did not have flower and have a very
strong taproot system which allowed them to have height up to 50 feet. Endemic to the Namib Desert, Welwitschia were adapted to have long flat
leaves which helps the plant to survive at higher temperature up to 65°C by
keeping the soil under the plant to stay cool and moist. The Namib Desert have averages fewer than 100 mm per year of rain
because receives no rainfall during some years.
They are around 80 percent of Angiosperms
which is the flowering plant out of all the living plant species in this earth.
As they are in higher plant group, angiosperms are vascular plants. They do have
stems, roots, and leaves. The different of angiosperms and gymnosperms is
angiosperms seed is in fruits meanwhile the flowers have male or female
reproductive organs. They need to undergo a pollination process before
they can reproduce. The male sex of Angiosperms called stamens. The pollen
grain of the angiosperms is made at the anther which located at the end of the stamen.
The pollen which develop from tissue contain many diploid microsporocyte then
undergoes meiosis to become microspores and then divides once by mitosis to be
separate will be taken to grow down to the stigma and style until reach
the micropyle of the ovule in the ovary. Or else known as pistil for the
female part of the flower. Then the unique event happened in angiosperms is
called double fertilization, where one sperms will unites with egg and form
zygote and the other one will unites with polar nuclei to form endosperm. After
the unique fertilization a fruit and seed is develop.