Botany For Dummies
Botany is the study of plants. Plants are very similar to people in a lot of ways, but they also have some differences that can be hard to wrap your brain around. And, like any science class, botany can get a little overwhelming at times. So here are a few items to help you grasp some of the big ideas in botany.
Parts of a Flower
Flowers can be unisexual, having only male or female parts, or bisexual, having both types of parts. The male parts of a flower make up the stamens. The entire whorl of stamens in the flower is called the androecium.
The sac-like structures at the top of the stamen are the anthers. The anthers house pollen, which contain the male gametophytes that make the sperm. The thread-like stalks that lift the anthers up are called filaments.
The female parts of the flower make up the pistils. The entire whorl of pistils in the flower, which may be separate or fused together, is called the gynoecium.
The sticky tips at the top of the pistils that receive pollen are called stigmas. The swollen bases of the pistils are the ovaries. Inside the ovaries are tiny pearl-like structures called ovules. The ovules contain the female gametophytes, which make the eggs. The slender stalks that connect each stigma to an ovary are called styles.
Alternation of Generations in a Plant Life Cycle
During the life cycle of a plant, the plant alternates between two forms: the sporophyte generation and the gametophyte generation. So, a complete plant life cycle includes both generations.
|Characteristics||Sporophyte Generation||Gametophyte Generation|
|Ploidy (# of sets of chromosomes)||Diploid (2 sets of chromosomes)||Haploid (1 set of chromosomes)|
|Types of cell division and what they’re used for||Mitosis to grow
Meiosis to produce haploid spores, which begin the gametophyte generation
|Mitosis to grow
Mitosis to produce haploid gametes, which join together to form the sporophyte generation
|How the generation begins||Begins when haploid gametes (sperm and egg) fuse to form a diploid zygote||Begins when the sporophyte produces a haploid spore|
|What it looks like in different kinds of plants||Most visible form in ferns, gymnosperms, and angiosperms
Small structures on mosses and lycophytes that grow on the gametophytes
|Most visible form in mosses and lycophytes
Small but independent structure in ferns’ very small structures in gymnosperms and angiosperms that are enclosed by the sporophyte
Types of Plant Tissues
Plant tissues come in several forms: vascular, epidermal, ground, and meristematic. Each type of tissue consists of different types of cells, has different functions, and is located in different places.
|Vascular tissue||Xylem is made up of vessels and tracheids
Phloem is made up of sieve cells and companion cells
|Xylem transports water
Phloem transports sugars
|In stems, leaves, and roots|
|Epidermal tissue||Parenchyma||Protect plant tissues and prevent water loss||Outer layer of stems, roots, and leaves|
|Makes up bulk of plant mass||Stems, roots, leaves|
|Meristematic tissue||Parenchyma||Divide to produce new growth||Tips of shoots
Tips of roots
In a ring around the stem in woody plants