Plant Tissues: A Rational for Study

Plants as organisms are quite impressive in consideration of their diversity, specialized structure, and biochemical attributes. Plants, like all living organisms, have basic needs for survival. Most of us are familiar with plant structures that provide for these needs, namely roots, stems, leaves, and flowers. There is great variety in these structures and biologists may never comprehend all the selective pressures exerted upon and within various plant groups. However, by examining the histology of plant structure and making comparisons between plants biologists gain insight into these selective forces. This plant tissue module is specifically designed to provide an understanding of basic plant histology. However, by learning plant cells and tissues insight into factors that determine variations in plant form follow.

 

In consideration of the basic needs all plants have we can make some important generalizations.. For example, all plants require support as they grow stems, branches with leaves or erect reproductive structures with flowers. Similarly, as multicellular organisms, most plants require tissues for transport, to move water and nutrients from one plant part to another. And finally, all plants require tissues for storage, for the pigments and products accumulated as they engage in photosynthetic activities. You will find plants assemble and employ these supportive, transport, and storage tissues in different ways; as adaptations to selective forces in nature. In this context, types and organizations of tissues can provide insight into speciation and the phylogeny of plant groups. A plant living today can be a surviving member of a group that appeared thousands or millions of years ago. If so, the structure of tissues in the living member can provide a view of more primitive attributes and adaptations to selective pressures spanning millions of years.

Physical forces do impose limits on cell sizes and shapes. As a result, plants have a limited number of cell types they can use to build more complex structure. A tissue by definition, is a collection of cells of common origin or structure working together to provide specific function! Since there are limited cell types plants can use, there are not many different types of tissues. Assume then, diverse structures within the plant kingdom are variations on common themes. Our goal here is to learn about these common themes!

Remember these key points!

All plants possess needs for support, transport, and storage!

Cells of common origin specialize in structure and function to form tissues!

All plant structures are products of a limited number of building blocks, cells and tissues, used in various combinations!

What we see today in a living plant is a product of selective forces that operate through time!


Module Overview and Launching Pad to Content


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