Micrographs of the root | From Seed to Seed: A Pictorial Story Showing How a Bean Plant Grows. Part 2 The Flowering and Mature Bean Plant

Meanwhile a lot is happening where you can’t see it!

Look at the plant roots!

The roots of plants are amazing structures. This whole mount viewed longitudinally (through the light microscope) shows the epidermis (yellow arrow). The meristem gives rise to the root cap and the cells of the root itself (white circle). The root cap (blue arrow) is at the tip of the root.

Figure 14. *Bean plant root.* A longitudinal section through the root of a red kidney bean plant. This whole mount viewed longitudinally (through the stereo microscope) shows the epidermis (yellow arrow), the meristem (circle) and root cap (blue arrow) of the root. Magnified 40 times. Credit: C.G. Elowsky

Around all the sides of the root and mainly right around the tip, root hairs protrude from the root. Root hairs absorb water and nutrients. They are modified epidermal cells.

Figure 15. *The root hairs on a bean plant root.* Bean plant root hairs (arrows). Magnified 100 times. Credit: C.G. Elowsky

Figure 16. *The root hairs on a bean plant root.* A root hair (arrow) is an expanded epidermal cell. Magnified 200 times. Credit: C.G. Elowsky

When the root is just emerging from the seed and beginning to form branch roots, the vascular tissues are still developing and are not easily identified.

Figure 17. *The bean plant root.* A cross-section through a very young bean plant root. Magnified 36 times. Credit: E.T. Paparozzi

As the root matures, all tissues become well defined and can be stained to distinguish one type of tissue from another.

Figure 18. A cross-section through a bean plant root. Since you can identify the tissues using colored stains, you know this is a mature bean plant root. Note the star shape (yellow) of the xylem in the center of the root. Magnified 100 times. Credit: C.G. Elowsky

Figure 19. *A cross-section through a bean plant root.* This is a closer view of the xylem which is the plant’s water and nutrient conducting tissue (yellow arrow). The xylem contains living and non-living (dead) cells. There are four branches (poles) of xylem that make up the star shape. There is more xylem than phloem (white arrow). Phloem is the ‘food’ conducting tissue. Magnified 200 times. Credit: C.G. Elowsky

Figure 20. *A light microscope view of an emerging bean plant root.* A branch root (arrow) is emerging from the main root. As the main root matures, more xylem tissue develops. Slide prepared by the Nebraska Veterinary Diagnostic Center. Magnified 50 times. Credit: E.T. Paparozzi

One way to look at roots dimensionally at a higher magnification is to use a scanning electron microscope (SEM). This process does not allow for color to identify these tissues.