Plant Tissue Under the Microscope

Today, I would like to share a few images taken of different plant tissues when viewed under a microscope. For this post, I selected 6 slides from my permanent slide collection, including slides containing root, leaf, and pollen samples.

Vicia faba leaf with Stomata:

This slide contains a section of a Broad bean (Vicia faba) plant that clearly shows microscopic pores known as stomata. Stomata are microscopic openings on the epidermis of leaf tissue that regulate the exchange of gases into and out of a plant. Typically being found on the underside of leaves, these structures are responsible for the intake of carbon dioxide to be used in photosynthesis as well as the expulsion of the oxygen produced as a byproduct of photosynthesis. The opening of each stoma is flanked by two specialized cells, known as guard cells, that regulate the size of the stoma's opening and thus the rate of gas exchange.

Root Meristem:

Meristematic tissue refers to undifferentiated stem cells found in a variety of locations in a plant body including the tips of roots and stems as well as in buds, nodes, and the cambium of dicotyledonous trees and shrubs. This tissue is characterized by densely packed cells with thin walls, large nuclei, and minimal intercellular space that continually divide to produce what will later develop into differentiated cell types within a plant body.

Onion Epidermis:

The epidermis refers to the outermost layer of cells that cover leaves, stems, roots, and flowers alike in plants. Depending on its location in the plant body, this single layer of cells is responsible for functions ranging from regulating gas exchange, to absorbing water, to secreting metabolic compounds.

Poa Leaf Cross Section:

This cross section of a leaf gives a better visual representation of some of the differentiated cell types found within the typical plant leaf. The outermost tissue shows epidermal cells dotted with the occasional guard cells of stomata. Internally, vascular tissue can be identified by large round cavities used to conduct nutrients and water throughout the plant body. Flanking these internal channels are mesophyll cells that contain the chloroplasts responsible for facilitating photosynthesis.

Young Pine Staminate Cone:

The lifecycle of gymnosperms, such as conifers, is characterized by alternating generations of diploid, spore-bearing generations known as sporophytes, and haploid, gamete-producing generations known as gametophytes. Conifers in particular produce both male and female cone structures. Male cones, containing pollen, are known as staminate cones, whereas female cones, containing ovules, are known as ovulate cones. Male cones are typically smaller than their female counterparts and are located on lower in the branches to reduce chances of a tree self-fertilizing as pollen are carried by the wind. Pollen grains in staminate cones are contained within structures known as microsporangium. This slide shows pollen grains located at the opening of one of a staminate cone's microsporangium. More information on the life cycle of gymnosperms can be found here.

Pollen Gem:

This pollen grain (gem) is an example of what an angiosperm's pollen may look like under a microscope. The ornately patterned texture to the outer surface of these pollen grains is referred to as exine ornamentation and is often used as acharacteristic for identification when the angiosperm that produced it is unknown. Examples of pollen surface patterns and terminology can be found here.