The grasses (also known as poaceae) are herbaceous (and some woody) plants that belong to the order of monocotyledons. There are more than twelve thousand species of grasses in almost all parts of the world.
There are two types of grasses, according to their life cycle:
- Annual grasses. They have a cycle and reproduce once a year. For example, wheat and oatmeal.
- Perennial grasses. They breed more than once a year. For example: grasses, bamboos.
Importance and use of grasses
Most grasses are used for product development as flour since most are cereals (barley, rice, wheat, among many others).
Others are used to manufacture paper mache, for which they use the stem or straw. In addition, the manufacture of ropes with stems and leaves of grasses is common.
Examples of grasses
- Birdseed
- Rice
- Oatmeal
- Bamboo
- Sugar cane
- Barley
- Rye
- Phalaris (Phalaris tuberosa)
- Robust Fescue
- Corn (Zea Mais)
- Son
- Orchard Grass (Dactylis Glomerata)
- grasses
- Sorghum
- Wheat
Stems
The stems of grasses are also called white hair because they are cylindrical and elliptical. They have solid knots, and between these knots, the canes are hollow, which allows them to have enough flexibility to grow in windy areas. In turn, the stems of grasses can be:
Aerial stems:
- Ascending stems. They are ascending and straight with short internodes near the base and more widely spaced towards the apex.
- Creeping stems. They are stems that do not ascend vertically but do so at ground level.
- Floating stems. They are herbaceous plants that grow in water and float thanks to the hollow stems of grasses.
Underground stems:
- Rhizomes. They are underground stems that give off (with horizontal growth) roots or shoots from their nodes.
- Pseudobulbs. They are stems that thicken at the internodes and are unusual among grasses (an example of this subclass is Phalaris tuberosa or birdseed.
Leaves
The leaves of grasses are composed of three parts:
- Sheath. It covers the stem and overlaps with it.
- Ligule. Membrane or group of hairs between the leaf blade and the petiole (in some species, it may not be present).
- Leaf blade. The lamina that covers most of the leaves of grasses.
Flowers and fruits
They have one structure called inflorescence. That is to say, the flowers are located at the end of the stem. In addition, the flowers of grasses can be unisexual or hermaphrodite. The fruits of grasses can be seeds (most grasses have a seed as their fruit), dry fruits, or caryopses.
It is important to note that grasses produce a significant amount of pollen which is distributed by the wind. Therefore, in the grasses that have sexual reproduction, the seeds are spread thanks to the action of the wind.