Plant Morphology

primary cell wall layer that is formed outside of the growing plant cell. There is also a secondary cell wall that is formed inside of the primary cell wall when the cell has matured.

PLANT MORPHOLOGY

Plant morphology is basically the same thing as plant anatomy from a macroscopic viewpoint. We will learn more about the structure and function of plants later in this chapter but in this part, we will look at the most obvious parts of the plant structure. In this section, we will look at the morphology of vascular plants, which is the typical plant one thinks of with regard to plants. Figure 41 shows the basics of plant morphology:

The roots of the vascular plant usually are not seen as they grow underground. They are responsible for the absorption of nutrients and water for the plant. There are two different types of roots: taproots and fibrous roots. The taproot is a single thick root extending beneath the plant with a network of roots that extend out from it. Fibrous roots are roots that have no taproot. There is just a dense collection of thinner roots without a major taproot. Both types of roots are covered in root hairs. The hairs increase the surface area of the root so that more water and nutrients can be absorbed.

The stems of the plant are the parts above the plant that hold the reproductive structures and the leaves. There are three types of stem tissues: 1) ground tissue (this is parenchymal tissue that makes up the bulk of the stem, 2) dermal tissue (this is the “outer skin” layer of the plant that protects the interior of the stem), and 3) vascular tissue (this involves the xylem and phloem of the stem or the vasculature of the plant).

The xylem is a tubular structure that moves water in one direction up the plant. The phloem is a tubular structure that moves water and nutrients up and down the plant. Water is moved up from the roots in the xylem, while energy and nutrients move through the plant from the leaves to the rest of the plant.

The leaves of a plant are the major area of photosynthesis. Most leaves are flat and green but, in other plants, the “leaves” can be needles as in conifer trees or thicker structures as in aloe plants. Leaves have dermal tissue, vascular tissue, and ground tissue, attached to the stem through a structure called a petiole. Leaves will have stomata, which are pores through which the water can pass in the process of evaporation. This contributes to the transpiration process, in which water moves throughout the plant. There is an outer cuticle and epidermis in plant leaves with mesophyll in between. Figure 42 shows the structure of the leaf:

The flower of a plant is referred to as an inflorescence. There are many types of flowers, all of which are the main reproductive structures of flowering plants. Flowers will carry both the male and female aspects of reproduction of a plant. These will be covered further when we talk about the reproduction of plants.

Fruit on a plant comes from the flowers and forms many different shapes and sizes. Fruits will hold the seeds of the plant and contain the plant’s ovary. Exceptions to this are fruits like strawberries, which are accessory fruits. This type of fruit comes from the head of the flower. On the accessory fruit are the seeds, which are mature plant ovaries that contain the seeds of the plant inside them.