Plants are essential to life on earth. Either directly or indirectly, they are the primary food source for humans and other animals. Additionally, they provide fuel, replenish the earth's oxygen supply, prevent soil erosion, slow down wind movement, cool the atmosphere, provide wildlife habitat, supply medicinal compounds, and beautify our surroundings.

Many plants are familiar to us, and we can identify and appreciate them based on their external structures. However, their internal structures and functions often are overlooked. Understanding how plants grow and develop helps us capitalize on their usefulness and make them part of our everyday lives.

This collection focuses on vascular plants--those that contain water- and nutrient-conducting tissues called xylem and phloem. Ferns and seed-producing plants fall into this category.

In several cases, we will distinguish between monocotyledonous and dicotyledonous plants. Sometimes called monocots and dicots for short, these plants have several important distinguishing characteristics. For example, monocots (e.g., grasses and cereal grains) produce only one seed leaf, while dicots have two. The vascular systems, flowers, and leaves of the two types of plants also differ. These differences will become important in our discussion of plant growth and development.

Comparison between monocots and dicots.
Structure Monocot Dicot
Seed leaves 1 2
Vascular system Xylem and phloem are paired in bundles, which are dispersed throughout the stem. Xylem and phloem inside the stem. The ring of phloem is near the bark; the xylem forms the inner ring.
Floral parts Usually in multiples of three. Usually in multiples of four or five.
Leaves Often parallel-veined. Usually net-veined.

Botany Topics

Plant Life Cycles

Based on its life cycle, a plant is classified as an annual, biennial, or perennial.


Internal Plant Parts

Cells are the basic structural and physiological units of plants. Plant tissues are large, organized groups of similar cells that work together to perform a specific function.


Vegetative Plant Parts

Vegetative plant parts include roots, stems, shoot buds, and leaves.


Reproductive Plant Parts

Reproductive plant parts produce seed; they include flower buds, flowers, fruit, and seeds.


Plant Growth and Development

Photosynthesis, respiration, and transpiration are the three major functions that drive plant growth and development.


Plant hormones and growth regulators

Plant hormones and growth regulators are chemicals that affect flowering, aging, root growth, distortion and killing of organs, prevention or promotion of stem elongation, color enhancement of fruit, prevention of leafing and/or leaf fall, and many other conditions.


Environmental Factors Affecting Plant Growth

Plant growth and geographic distribution are greatly affected by the environment. Either directly or indirectly, most plant problems are caused by environmental stress. Environmental factors that affect plant growth include light, temperature, water, humidity, and nutrition.

By Ann Marie VanDerZanden | Article

Plant communities

Interactions between plants are important for gardeners. The study of these interactions is called plant or landscape ecology.


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