SACCONE IS THE COOLEST Chapter 26 Sexual Reproduction in Plants

SACCONE IS THE COOLEST (I) Structure of the Flower Some flowers contain both stamen and pistil while other flowers contain only one of the two Petals and sepals are also present in flowers

SACCONE IS THE COOLEST (I) Structure of the Flower The complete circle of petals is called a corolla The complete circle of sepals is called a calyx.

SACCONE IS THE COOLEST (A) Stamen Male reproductive structure Composed of an anther and filament Through meiosis, the diploid cells of the anther produce pollen grains that are haploid

SACCONE IS THE COOLEST (B) Pistil Female reproductive structure Composed of stigma, style, and ovary As a result of meiosis, the eggs developing inside the ovary are haploid

SACCONE IS THE COOLEST (III) Pollination The transfer of pollen grains from the anther to the stigma Pollination may be aided by wind, insects, and birds. In some instances, the colored petals act as a visual attractant for insects If pollination occurred in a dry environment, the pollen grain would not dehydrate (dry up) due to a thick wall that surrounds it Two types of pollination: 1. Self-Pollination 2. Cross-Pollination

SACCONE IS THE COOLEST Self-Pollination The transfer of pollen grains from the anther to the stigma of the same plant

SACCONE IS THE COOLEST Cross-Pollination The transfer of pollen grains from the anther of a flower one one plant to the stigma of a flower on a different plant Allows for variations due to the combination of two different plants

SACCONE IS THE COOLEST Following pollination, the pollen grain germinates to the stigma and forms a pollen tube Pollen tube is an adaptation for internal fertilization Two haploid sperm cells travel down the pollen tube and only one fertilizes the egg in the ovule

SACCONE IS THE COOLEST (IV) Fertilization and Embryo Development The union of a sperm cell and an egg cell results in the formation of a zygote The zygote undergoes development resulting in the formation of an embryo (ripened ovule) The ripened ovule develops into the seed The ripened ovary develops into the fruit

SACCONE IS THE COOLEST Plant Embryo (seed) Hypocotyl- develops into the root, and in some species, the lower portion of the stem Epicotyl- develops into leaves and the upper portion of the stem Cotyledon- contains stored food and provides nutrients for the germinating plant

SACCONE IS THE COOLEST (V) Germination In flowering plants, seeds develop within fruits which are specialized structures that aid in seed dispersal Ex: animal eats fruit  feces Germination will occur if there is: 1. Sufficient moisture 2. Proper temperatures 3. Oxygen

SACCONE IS THE COOLEST (VI) Growth Growth occurs in specific regions known as the meristematic region Two types: 1. Apical meristem- region of growth found in the tips of stems and roots (length of plant) 2. Cambium- region of growth located between the xylem and phloem (width of plant)