Stem types

As we have mentioned above, the stem is the mainly aerial part of the plant that is responsible for giving structure to it and supporting its different organs, such as leaves, flowers and fruits. Thus, its two main functions are the support and transport of nutrients and substances between roots and leaves, the result of feeding processes in the former and photosynthesis in the latter.

The stems show negative geotropism, which means that they grow in the opposite direction to gravity. They also have knots, from which the leaves are born, and with different types of internodes and buds.

In addition, in some types of plants, the stem can have specialized functions, such as the storage of nutrients in tubers or the presence of tendrils in some climbing plants.

The classification of the stems can be done according to the medium:

• Underground.
• Aerial.
• Aquatic.

Below we will explain each of these types and discuss their subtypes in detail and examples. In addition, we will also talk about the types of edible stems, the majority being underground and aerial.

The underground stems are those that, as their name suggests, develop underground . They have buds that give rise to both branches and adventitious leaves and roots. There are several types of underground stems , as they can be subdivided into:

• Tubers: they are short and very thick, and are characterized by storing reserve substances and nutrients. They have slits, commonly called eyes, that give rise to aerial stems. Some examples of tuber are potato , cassava, maca and Jerusalem artichoke.
• Rhizomes: thick underground stems that develop parallel to the soil surface. They create protective scales and, when the warm months arrive, their buds give rise to shoots that grow outwards. Examples of rhizomes are lily, ginger , grass, and bamboo . Here you can learn more about rhizomes, their definition and examples of plants .
• Bulbs: they form a capsule that has a short stem with roots at the base and a bud at the upper end, surrounded by several layers of special leaves that serve as a store for reserve substances. In the warm months the stem grows to the outside, and in the cold the bulb survives underground. The onion and the tulip are bulbs . In this other post you can find out more about 15 bulb plants .

Aerial stems are those that grow and develop above ground level . They are divided into several types of aerial stems :

• Upright: they grow completely vertically, without the need for other supports.
• Crawlers: they are not rigid, so they develop horizontally. Examples of creeping stalks are pumpkin and carrot .
• Climbers: use the support of other plants or external objects. An example is the paper flower or helichrysum and the minor bougainvillea .
• Volubles: stems of very little resistance, which develop in a spiral around the stem of a support, which can be another plant or any tutor. An example is the bell.

There are other special types of aerial stems are:

• Large trees and shrubs develop a trunk, a highly branched and resistant stem.
• Some plants have stems that are called cane . They are cylindrical and have very marked knots. An example of this is wheat.
• Like strawberries, some creeping stems are capable of developing at ground level and creating roots to give rise to new plants. These are the so-called stolons .
• Some climbing plants, such as the vine, have specialized stems , in the form of a thin spiral, whose function is to allow the plant to grasp the supports within reach. These are the tendrils .
• Some stems, like those of rose bushes, develop thorns as a defensive measure against predators.

The aquatic stems develop in flooded areas or in places flooded with mud, that is, in land with a lot of puddled water. They can be seen both in submerged plants and in those that float on the surface. Some examples of types of aquatic stems are:

• Water hyacinth
• Water lilies, such as Nymphaea tetragona
• Pistia or water lettuce

If you want to know more examples, here you can see +50 aquatic plants, their names, characteristics and images .

To end this list of types of stems , we want to comment that another way to classify them is according to whether they are edible or not. In fact, there are a large number of types of edible stalks that the different cuisines of the world use regularly.

From the most obvious, such as asparagus , radishes, chard or celery, to others less known in the West, such as bamboo or fern shoots. The latter are usually eaten after light cooking, while bamboo shoots have been consumed in Asia since ancient civilizations, cooked and salted or preserved. Furthermore, not everyone is aware that cinnamon, used as a spice, is also consumed for its stem. Another plant traditionally consumed as food and for its medicinal properties is fennel, consumed in many different ways and key in Provencal cuisine. Finally, other examples are sugar cane, shallot, rhubarb and chard, consumed not only for its leaves but also for its white stem, called penca.