Ed Golson Outdoor Education

basic plant structure

Plants come in a variety of different shapes and sizes. Not all plants have the same basic structure, but most of them share many different characteristics.

Roots
Roots are the base of plants. Unlike the rest of the plant, roots grow downwards into the ground providing a support for the stem and anchoring the entire plant to the plant1ground. Aside from providing support for the plant, roots also provide the very important job of absorbing nutrients and water from the soil. There are two major types of root systems in plants: taproot systems and fibrous systems. Taproot systems are found in plants such as nut trees, carrots, radishes, parsnips and dandelions. These taproot plants have a single main root with only a few roots growing outwards from it (much like a carrot with small branches). Taprootsplant2 are often used to store extra sugar in the plant. Fibrous plants, however, have many branched out roots. Grasses, and beans are some examples of fibrous roots. Fibrous roots also provide a stronger hold to the ground for plants. Try pulling a carrot (a taproot plant) out of the ground compared to pulling a few blades of grass (a fibrous rooted plant) with all of its roots and see which is harder to pull!
So we see the differences in how the roots act to support the plant, but how does it keep it alive being so far into the ground? The plants roots, be it taproot or fibrous, all have root hairs growing from main roots. These root hairs absorb water and nutrients from the soil and feeds it to the entire plant. Some plants can have over 14 billion roots hairs, such as the rye plant which is no bigger than wheat. All those roots hairs can make up the surface area of an entire football field!

Stems
 Stems are the main trunk of the plant. Stems usually grow outwards from the ground and are usually the easiest part of the plant to identify.  They carry the water and nutrients provided by the roots to the buds and shoots that grow from the stem itself. Stems act as a support for leaves, flowers and fruits. In some cases, stems can also store food for the plant. Stems come in many sizes ranging from tall (sunflowers or trees) to short (dandelions).

One of the most important function of a stem is to move water and minerals through the plant. In humans, our vascular system moves blood through out bodies as the digestive moves food. In plants the water/mineral moving system is called the xylem (ZYEY-lem) and the food-moving is called the phloem (FLOW-em). These systems are like tubes inside the stem that travels everywhere to the plant that requires water, mineral and food.
The cambium is also another important part of the stem. The cambium is found in two separate areas of the plant; encircling the stem and in the buds. Cambium that is found in buds helps to increase the length of the plant while cambium that encircles the stem increases girth. Injuring the cambium layer in some plants can result in killing the plant such as trees.

Leaves
 plant3Leaves are outgrowths of the stem.  Their primary function is to produce food for the plant. Leaves are usually flat, wide and green, though some can be narrow and pointed like pine needles. The broad shape of leaves help them catchpine needle the sunlight and make food through photosynthesis. The outside of leaves are covered by a waxy cuticle. Cuticles prevent harmful organisms from entering the plant and also prevent drying out. The leaves also have tiny holes on them called stomata that regulate the amount of water and gasses that enter and leave the plant.

Buds
Buds are undeveloped flowers, fruits, and shoots of a plant. The places plant5where buds formplant6 on the stem are called nodes.  Buds can be classified in two categories: terminal and lateral. Terminal buds are usually found on the tip of a stem while lateral buds are found on the sides of the stems. An example of a plant with lateral buds are lilacs and an example of a terminal buds are cabbages.

 

Fruits
Fruits are the ripened ovary or group of ovaries containing seeds. When the fruit starts off, it is unfertilized.  When the ovary is fertilized, the seeds develop and the ovarysunflower enlarges forming the mature ripened fruit. There are different ways that fruits can form. Simple fruits are formed by simply ripening the ovary of a single pistil (sunflower seeds, grains, peanuts). Aggregate fruits form from several simple pistils that form fruits like raspberries and strawberries. Multiple fruits form from a cluster of several flowers such as pineapples and grapes. Fruits help to get seeds dispersed from the parent plant so that seedsthey don't end up competing with each other as they grow. Some fruits, like those from maple trees or milkweeds, are shaped in such a way to make it easier for the wind to blow the seed away. Some seeds are covered with sweet and attractive flesh so that animals will come along and eatMalus the fruit, with the seeds inside. The seeds can then pass through the animal unharmed and land some distance from their parent. Some seeds actually need to be digested before they will germinate.

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