Botany Basics, Parts of a plant leason

Diagram of external plant parts (from OSU Master Gardener Program).

The different plant structures are actually called organs. Each organ is a specific type of tissue that performs a particular function. For today’s blog, I’m only going to focus on the vegetative parts. These include the roots, stems, shoot buds, and leaves. The second group of structures has to do with sexual reproduction. I will save this latter group for part 2, next week.

Interesting note: Even though the vegetative parts are not involved in sexual reproduction, they can be used in asexual reproduction such as cuttings or grafting.

Roots: They have the principal function of the absorption of water and nutrients, and they also act as an anchor for the plant and a support for the stem.

A primary root that has few lateral roots and continues to extend downward is called a taproot. An example of a taproot would be a carrot, a root that we eat as a vegetable. If the primary root stops elongating and many lateral roots develop, the root is referred to as fibrous. An example of a fibrous root structure would be turf grass.

Gardening tip: When transplanting a young plant into the garden or planting a seed, do not put fertilizer in the transplant hole or next to the seed. Instead, place a band of fertilizer 2 inches below and 2 inches to the sides. As the plant begins to grow, the roots will soon reach the needed nutrients for optimal early growth.

Stems: Their function is to be the plant’s plumbing system, carrying water, dissolved nutrients and sugars. Stems also have nodes which are areas of active cellular growth. Nodes are where small buds develop into leaves, stems or flowers.

Here are some very interesting facts about stems. We think of stems as being above ground, but they also grow below ground in the form of rhizomes (bluegrass), tubers (potatoes), corms (gladiolus) or bulbs (daffodils). To be classified as stem tissue, it must have nodes for buds or leaves.

There are also specialized above-ground stems. Stolons are horizontal stems, sometimes called runners (strawberry), crowns are compressed stems and leaves (dandelion), and spurs which are short, little side stems that are fruit bearing (pear, apple, and cherry). A stem that we commonly eat is asparagus.

Buds: They are the location of an undeveloped shoot that will either be a leaf or a flower. Leaf buds tend to be less round and more elongated, and flower buds are the opposite.

Terminal buds are located at the tip of a stem and lateral (axillary) buds are located on the sides of a stem. A terminal bud that we eat is cabbage. A lateral bud that we eat is brussels sprout. Broccoli is an example of a flower bud that is eaten.

Leaves: The main function of a leaf is to absorb sunlight and to produce sugars through the process called photosynthesis. The leaf can be stalkless and attach directly into the stem, or it can be attached with a little stem called a petiole. An example of a leaf that we eat would be lettuce. A petiole that is eaten is rhubarb.