Virtual Cell Biology Lab

I. Evolution of Vegetative Structures

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A. Moss

1. Observe the living green "leafy" gametophyte stage on the right. Remember that these organisms have leaf-like, stem-like, and root-like structures. You can see more of the details by magnifying the image.

(Note: Click on the image or on the word "magnify" to enlarge the images).

2. Now examine the cross section of a moss (Mnium) "stem". You can see the general structure of the "stem." Magnify the image and identify the following structures.

a. the outer epidermal cells
b. the "leaves" attached to the epidermis
c. the multicellular cortex region
d. the transport tissue

(Although some of the cell walls in the cortex are stained red, moss is a nonlignified plant.

The central portion of the "stem" is composed of much thinner cells. While the central cells are specialized to transport water, they are not lignified so they are not called "vascular tissue." [And therefore, moss plants do not have leaves, stems, and roots.]

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