In evolution, new structures or organs often
originated by modification of previously existing
structures or organs.
Comparisons of the arrangement of vascular
tissues in both flowers and leafy stems and of
In the middle of Jurassic period (180 million
years ago –mya-) several gymnosperm lines
existed, resembling those flowering plants.
Coevolution is a mutual adaptation between
plants and their animal pollinators.
Paleobotanists ( biologists who study fossil
plants) determined that ancient gymnosperms
are in the direct line of evolution leading to the
Gnetophytes are the gymnosperm group.
The oldest definitive trace of flowering plants
in the fossil record in Jurassic and Lower
Cretaceous rocks some 125 million to 145
million years old.
The oldest fossilized flowers are about 118
million to 120 million years old
These are : Amborella, Water Lilies and Star
Basal Angiosperms consists of 170 species
thought to be ancestral to all other flowering
It is also arranged spirally (as opposed to
fewer parts with a whorled arrangement).
And the oldest surviving group of basal
angiosperms is represented by a single living
species which is AmborellaTrichopoda.
Core Angiosperm are divided into three
subgroups: Magnoliids, Monocots and Eudicots.
Magnoliids is the group of flowering plants and
classified traditionally as “dicots”.
Magnoliids include several economically
important plants such as black pepper,
avocado,nutmeg, and bay laurel.
Flowering plants as the principal photosynthetic
organisms in land, provide other organisms with
a continuous supply of energy that they must
have to survive.
All animals require flowering plants directly or
Magnolia family (Magnoliaceae).
They are easy to recognize because they have
simple, alternate leaves and
large, conspicuous flowers that contain
numerous stamens and pistils.
The fruit is conelike.
And about 220 species of trees and shrub
native to temperate and tropical areas of Asia
Walnut Family (Juglandaceae).
Walnut family are monoeciuos and bear
separate male and female flowers on the
The leaves are pinnately compound and
arranged alternately on the stem.
The male flowers occurs in catkins clusters of
tiny pendulous stalk, produce pollen that is
carried by the wind to a female flowers.
The female flowers are small, lack petals, and
usually occur individually on small, erect
And about 50 to 60 species of
walnuts, hickories, and pecans. All are
deciduous trees native to the temperate and
subtropical areas of Asia and North and South
The Cactus Family (Cactaceae).
There are more 200o species of perennial
herbs, vines, shrubs, and small trees that are
native to North and South America, also
naturalized in China, India and the
The greatest number and variety of cacti
occur in Mexico; in USA most abundant in
Texas, Arizona, and New Mexico.
Cacti usually live in deserts and are succulent
Most cacti have spines.
Cacti are of economic importance primarily
as ornamentals, although some are cultivated
for their fleshy, edible fruits.
Some cactus species are in danger of
extinction because they have been over
collected for “ desert landscaping “.
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