What are xylem what is their purpose

Plant transport tissues - Xylem and phloem Xylem The xylem is a tissue which transports water and minerals from the roots up the plant stem and into the leaves. The cells that make up the xylem are adapted to their function: They lose their end walls so the xylem forms a continuous, hollow tube. They become strengthened by a substance called lignin. Lignin gives strength and support to the plant.

We call lignified cells wood. Phloem The phloem moves food substances that the plant has produced by photosynthesis to where they are needed for processes such as: growing parts of the plant for immediate use storage organs such as bulbs and tubers developing seeds Transport in the phloem is therefore both up and down the stem.

The cells that make up the phloem are adapted to their function: Sieve tubes - specialised for transport and have no nuclei. Each sieve tube has a perforated end so its cytoplasm connects one cell to the next. Sucrose and amino acids are translocated within the living cytoplasm of the sieve tubes. Companion cells - transport of substances in the phloem requires energy. One or more companion cells attached to each sieve tube provide this energy. Phloem consists of living cells.

The cells that make up the phloem are adapted to their function:. Plant transport tissues - xylem and phloem Xylem The xylem transports water and minerals from the roots up the plant stem and into the leaves.

Vessels: Lose their end walls so the xylem forms a continuous, hollow tube. Become strengthened by a chemical called lignin. The cells are no longer alive. Lignin gives strength and support to the plant. We call lignified cells wood. Phloem The phloem moves food substances that the plant has produced by photosynthesis to where they are needed for processes such as: growing parts of the plant for immediate use storage organs such as bulbs and tubers developing seeds Transport in the phloem is therefore both up and down the stem.

It also provides storage and support to the plant Myburg. In simple terms, xylem is a type of vascular tissue responsible for conducting water throughout the plant body.

Xylem comprises complex systems and several types of cells for transporting water and dissolved minerals to support and provide nutrition to plants. What are xylem and phloem? Xylem and phloem are vascular tissues responsible for transporting water and food, respectively. How is xylem different from phloem? You can also look at the table below.

Also, you may read this for phloem definition and more information. What is the role of xylem in a vascular plant? The phloem of vascular plants is responsible for transporting nutrients including, sugar , proteins , and organic molecules that help plants to remain alive and reproduce.

Angiosperms known as flowering plants are one of the major groups of vascular plants. The others are gymnosperms naked seed-producing plants and pteridophytes e. These groups can be distinguished based on their xylem tissues. For instance, the xylem tissues of flowering plants contain xylem vessels that are absent in the xylem tissues of gymnosperms or ferns. They have no xylem vessels but only tracheids. In most angiosperms, the xylem vessels serve as the major conductive element.

Nonetheless, both tracheids and xylem vessels lose their protoplast at maturity and become hollow and non-living. The polymer lignin is deposited forming a secondary cell wall. The xylem vessels, though, have thinner secondary walls than the tracheids. Then, both of them form pits on their lateral walls.

The xylem vessel is a series of cells called vessel members or vessel elements , each with a common end wall that is partially or wholly dissolved. This is in contrast to a tracheid, which is an individual cell. Also, the tracheid cell is typically longer than the vessel member. However, the vessel member is wider in diameter. Because of this, the xylem vessel conducts more water than the tracheid. Angiosperms may be grouped into two major groups: 1 the monocots e.

The two groups are differentiated basically by the number of cotyledons they have — monocots have one cotyledon whereas dicots have two. Apart from the cotyledons, they can also be differed by their xylem tissues.

In particular, the xylem of a dicot root has a star-like appearance 3 or 4-pronged. See Figure 4. In contrast, the monocot root has alternating xylem and phloem tissues. Another marked difference between the two in terms of xylem tissues is the xylem vessels.

Dicot roots have polygonal or angular xylem vessels whereas monocot roots have oval or rounded. The xylem-phloem elements are fewer in dicot roots typically 2 to 6 than in monocot roots typically 8 or more. Apart from the roots, the dicots and the monocots have apparent differences in their stems. The vascular bundles i. Furthermore, dicots have secondary growth. In their stems, they form growth rings annual rings. Thus, this leads to a subgroup of dicots: herbaceous dicots e.

In woody plants, there produce two types of xylems: 1 primary xylem and 2 secondary xylem. The primary xylem is responsible for the primary growth or the increase in length. The secondary xylem also called wood is for secondary growth, which is the increase in girth. Angiosperms are not the only ones that produce wood secondary xylem , though. Gymnosperms also produce wood.

The angiosperm wood is called hardwood whereas gymnosperm wood is called softwood. The name is due to hardwood being more compact and denser than softwood. If you will recall, the angiosperms have xylem vessels apart from tracheids. Most gymnosperms have only tracheids. Thus, this makes many hardwoods denser than softwoods. However, there are exceptions. Yews and longleaf pines are softwoods that are extremely durable and harder than many other hardwoods. On the basis of structure, development, function, and role of xylem tissue, the biologists divided xylem divided into two main types, i.

These two types of xylem perform the same function and are categorized by the type of growth for their formation. The primary growth of plant formation of primary xylem occurs at the tips of stems, roots, and flower buds. Also, the primary xylem helps the plant to grow taller and makes the roots longer.

Thus, it occurs first in the growing season, so this is called primary growth. The purpose of primary and secondary xylem is to transport water and nutrients. With the secondary growth of the plant, secondary xylem is formed that helps the plant to get wider over time. An example of the secondary growth of plants is wide tree trunks. It happens each year after the growth. Plus, the secondary xylem gives dark rings that determine the age of trees. Xylem consists of four types of elements: 1 xylem vessels, 2 tracheids, 3 xylem fiber, and 4 xylem parenchyma.