CHAPTER 25

THE PLANT KINGDOM: FLOWERING PLANTS

THE EVOLUTION OF FLOWERING PLANTS

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 the developmental.

Flowering plants probably descended from gymnosperms

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 flowering plants.

Gnetophytes are the gymnosperm group.

TRIVIA: 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

The basal angiosperms comprise three groups

These are : Amborella, Water Lilies and Star Anise

Basal Angiosperms consists of 170 species thought to be ancestral to all other flowering plants.

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 Amborella Trichopoda.

Magnoliids, monocots, and eudicots composes the core angiosperms

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.

A Survey of 12 Flowering Plant Families

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 indirectly.

Organisms: -deer -garter snake -toad -grasshoppers

The Magnolia Family includes ornamentals and timber trees

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 and America.

The Walnut Family provides nuts and woods for making furniture

Walnut Family (Juglandaceae). Walnut family are monoeciuos and

bear separate male and female flowers on the same plant.

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 stalks.

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 America.

The Cactus Family is important for its ornamentals

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 Mediterranean.

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 plants.

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 “.