The plant kingdom is divided into a number of divisions (sometimes called phyla) . There are 12 living divisions in the Plant Kingdom and numerous extinct divisions. Plants in a division share common characteristics. For this class, we will be concerned with only three Divisions: the Division Coniferophyta, Division Ginkgophyta, and Division Anthophyta.
These three divisions are separated by reproductive features. In two divisions, the Coniferophyta and Ginkgophyta, the seeds are not enclosed in an ovary. The informal term for these two divisions is "gymnosperm", which means "naked seed" in reference to this feature. The third division, the Division Anthophyta, is composed of the flowering plants. Members of this group produce flowers, and their seed is enclosed inside the ovary (fruit). The Division Anthophyta is informally called "angiosperm".
In a complex world it is natural to organize objects into groups. Grouping objects makes it easier to work with a particular subject. For example, when selecting plants for your garden you might place plants into two groups: sun and shade plants. These could be called "functional groups", and recognizing them is an important landscape design tool.
When botanists place plants into groups, the goal is to organize plants into natural groups; groups that represent relationships. Plants that are in the same group are more closely related to each other than those in two different groups. Some of the groups used by botanists include the plant kingdom, plant divisions, plant classes, families, genera and species.
As you read through the next topic, notice how quickly the plant kingdom gets broken down into divisions. Those divisions will be broken down even further into smaller groups, such as classes, then families, genera and eventually the smallest division, the species. The species is the basic unit of this classification system; you can think of the species as a "kind" of plant. For example, the blue oak is a species or kind of plant.
If this system seems complex, it is. It is a reflection of the complexity of the plant kingdom. As a horticulturist, it is good to have a general understanding of this organization, if for no other reason than to help you identify plants.
Kingdom Plantae - the Plant Kingdom
All plants are placed into one kingdom, the Kingdom Plantae. One of the most significant features of plants is the presence of the green pigment, chlorophyll. Chlorophyll traps light energy to make food (sucrose sugar and starch), and in the process produces oxygen. Additionally, members of this kingdom are multicellular and have cell walls composed of a chemical called cellulose.
STUDENT RESEARCH QUESTION:
1. Plants use sunlight energy to make food by a process called photosynthesis. What are the two common molecules that the plant gets from the air and soil to produce sucrose sugar and starch?
The Plant Kingdom – an overview