26.3 Angiosperms

• The compound ephedrine comes from the small, scale-like leaves of the plant.
• Because it is similar to amphetamines, its use is restricted to prescription drugs.
• Some parts of Africa, South America, and Southeast Asia have gnetum species.
• The oddest member of the group is Welwitschia.
• Some plants are hundreds of years old and produce only two leaves.
• The male and female gametes are produced on different plants.

• The strangeness of Welwitschia is described in a video.

• The angiosperms--or flowering plants-- have evolved to dominate most of the land.
• The Anthophyta has more than 300,000 species and is second only to insects in terms of diversity.

• There are flowers in a garden.
• Plants are abundant in the landscape.

• The vivid colors of flowers are adapted to pollination by animals like insects, birds, and bats.

• The reproductive structures of flowers and fruits are responsible for the success of angiosperms.
• The flower's function is to ensure pollination and protect a developing embryo.
• The colors and patterns on flowers can be used to identify birds and bats that have coevolved with them.
• Some patterns can only be seen in the ultraviolet range of light.
• For some people, flowers are a reliable source of food.
• The scent of the flower helps to find its pollinators.
• Some flies and beetles prefer scents that signal putrefaction, which is why sweet scents attract bees and butterflies.
• The ovule and developing embryo are protected by flowers.
• The fruit is used for seed protection and dispersal.
• The dispersal strategies that help spread seeds are reflected by the different fruit structures or tissues on fruit.

• The flowers are organized around a central receptacle.
• The structures of the flowers are the same, even though they vary greatly in appearance.
• The flower is usually attached to the plant by the peduncle.
• There are some exceptions to the fact that Sepals are usually photosynthetic organs.
• The corolla in lilies and tulips has three sepals and three petals that are almost identical.
• The sexual organs are located at the center of the flower.
• The gynoecium may be located deeper in the receptacle, with the other floral structures attached above it.

• Each of the carpels in the female reproductive unit has a stigma, style, and ovary.
• Carpels can be singular, multiple, or fused.
• The anther is supported by the filament, where the microspores are produced by meiosis and develop into haploid pollen grains.

• The structure of a flower is depicted.
• Male and female floral organs are produced by perfect flowers.
• Some flowers have more than one carpel, but the flower shown has one.
• The gynoecium is made up of all the carpels.

• The main phase of an angiosperm's life cycle is the adult phase.
• Gymnosperms are Heterosporous.
• The male and female gametophytes will form an ovule that contains female gametophytes.
• Inside the anther's microsporangia, male sporocytes divide by meiosis and give rise to haploid microspores, which in turn give rise to pollen grains.
• There are two cells in a pollen grain, one of which will become a sperm and the other will become a pollen tube cell.

• The life cycle of a plant is shown.
• The embryo sac and the pollen grain are the actual gametophytes.
• The process of double fertilization is unique to angiosperms.

• The megasporangium is protected by two layers of integuments and the ovary wall.
• There are three small and one large haploid megaspores within each megasporangium.
• The megaspore divides three times to produce eight nuclei in the female gametophyte or embryo sac.
• There are three cells located at the embryo sac.
• The three cells at one pole become synergids.
• The center cell has two nuclei.
• The endosperm of the seed will eventually be produced by this cell.
• The mature embryo sac contains one egg cell, two synergids or "helper" cells, three antipodal cells, and a central cell with two polar nuclei.
• When a pollen grain reaches the stigma, a pollen tube extends from the grain, grows down the style, and enters through the micropyle: an opening in the integuments of the ovule.
• The embryo sac contains sperm.

• There is a double fertilization event.
• The sperm and egg combine to form a diploid embryo.
• The tissue is used as a food reserve for the embryo.

• The basis for the two major groups of angiosperms is the difference in the number of leaves.
• The seed food reserves are stored outside of the embryo.
• The embryo is protected by a layer of integuments forming the coat, the endosperm with food reserves, and at the center.

• Male and female flowers are carried on the same plant.
• There are male and female flowers in dioecious plants.
• Crosspollination can be accomplished by either a physical agent (wind or water) or an animal.

• There is a female inflorescence.
• There is a male inflorescence.

• The walls of the ovary begin to form fruit as the seed develops.
• As the seeds grow, the ovary enlarges as the seed forms.
• Vegetables are actually fruits.
• Tomatoes, bell peppers, and string beans are all technically fruits because they are derived from the thick ovary tissue.
• The winged maple "helicopter seeds" or whirligig are also fruits.
• Only a few of the fruit categories are actually sweet.

• Fruit that is mature can be dry.
• Fruit with flesh include the familiar berries, peaches, apples, grapes, and tomatoes.
• Some examples of dry fruit are rice, wheat, and nuts.
• Not all fruits are derived from the ovary.

• Some fruits are derived from different parts of a flower.
• Some fruits, like watermelon and orange, have rinds.
• Fruits are an agent of seed dispersal.
• The dispersal mode is reflected in the variety of shapes and characteristics.

• Light dry fruits of trees and dandelions are carried by the wind.
• Water moves coconuts.
• The seeds are dispersed through the feces of the herbivore.

• Other fruits have hooks to hold onto fur and hitch rides on animals.

• Modern angiosperms are thought to be a monophyletic group, which means that they originated from a single ancestor.
• There are three major groups within the angiosperms.
• Basal angiosperms are a group of plants that are thought to have branched off before the separation of the monocots.
• They are categorized in different ways.
• The Magnoliids, which include the star anise, are part of the angiosperms.
• The structure of the cotyledons, pollen grains, and other structures are used to differentiate the monocots and dicots.
• The dicots form a multi-branched group that includes roses, cabbages, sunflowers, and mints.

• The magnolias, laurels, and peppers are part of the Magnoliidae.
• Magnolias are tall trees with large, fragrant flowers and are considered archaic.
• The magnolia flower's petals are undifferentiated and called tepals.
• The reproductive parts are arranged in a spiral around a cone-shaped receptacle.
• There are fragrant leaves and flowers in the trees.
• The Laurales are small trees and shrubs that grow in warmer climates.
• The bay laurel, cinnamon, and spice bush are familiar plants in this group.

• There is a cluster of carpels above the inflorescence, which have shed their pollen.
• The petals and sepals of the flower are undifferentiated.

• Black pepper is the main product that was traded along spice routes.
• The leaf venation is similar to the monocots and the dicots.

• The roots of the plant are at the bottom of the lake and are visible from the surface of the water.
• The red seeds are starting to appear on the fruit in its final stage.

• There are veins that run parallel to and along the length of the leaves and flower parts that are arranged in a three- or six-fold symmetry.
• Most of the time, true woody tissue is not found in monocots.
• The primary and secondary thickening meristems form the trunk in palm trees.
• The feature is still present in the modern monocots.
• There is a ring in the roots of the stem that holds the scattered tissue.
• There is no major tap root in the root system.
• Adventitious roots emerge from the leaves.
• Plants such as the true lilies (Liliopsida), orchids, yucca, asparagus, grasses, and palms can be found in the monocots.

• The world's major crops are flowering plants.

• Flower parts come in four, five, or many whorls, and Veins form a network in leaves.
• In monocots, the stem has a ring in it.
• The pollen that is trisulcate or triporate is produced by most eudicots.
• The root system is usually anchored by a single root.
• Two-thirds of flowering plants are Eudicots.
• Table 26.1 summarizes the major differences between monocots and Eudicots.
• Identification of a plant as a monocot or eudicot is not always easy because some species may exhibit characteristics that are associated with the other group.