How can water be transported into the leaves of a tree?

Answer 1

with the help of XYLEM and PHLOEM present in the tree vascular tissues.

phloem is the innermost layer of the bark ,

StructureMultiple cross sections of a stem showing phloem and companion cells[1]

Phloem tissue consists of less specialized and nucleate parenchyma cells, sieve-tube cells, and companion cells (in addition albuminous cells, fibers and sclereids).

Sieve tubes

The sieve-tube cells lack a nucleus, have very few vacuoles, but contain other organelles such as ribosomes. The endoplasmic reticulum is concentrated at the lateral walls. Sieve-tube members are joined end to end to form a tube that conducts food materials throughout the plant. The end walls of these cells have many small pores and are called sieve plates and have enlarged plasmodesmata.

Companion cells

The survival of sieve-tube members depends on a close association with the companion cells. All of the cellular functions of a sieve-tube element are carried out by the (much smaller) companion cell, a typical plant cell, except the companion cell usually has a larger number of ribosomes and mitochondria. This is because the companion cell is more metabollically active than a 'typical' plant cell. The cytoplasm of a companion cell is connected to the sieve-tube element by plasmodesmata.

There are three types of companion cell.

1. Ordinary companions cells - which have smooth walls and few or no plasmodesmata connections to cells other than the sieve tube.
2. Transfer cells - which have much folded walls that are adjacent to non-sieve cells, allowing for larger areas of transfer. They are specialised in scavenging solutes from those in the cell walls which are actively pumped requiring energy.
3. Intermediary cells - which have smooth walls and numerous plasmodesmata connecting them to other cells.

The first two types of cell collect solutes through apoplastic (cell wall) transfers, whilst the third type can collect solutes symplastically through the plasmodesmata connections.

In vascular plants, xylem is one of the two types of transport tissue, phloem being the other. The word "xylem" is derived from classical Greek ξυλον (xylon), "wood", and indeed the best known xylem tissue is wood, though it is found throughout the plant. Its basic function is to transport water.

Physiology of xylem

The xylem is responsible for the transport of water and soluble mineral nutrients from the roots throughout the plant. It is also used to replace water lost during transpiration and photosynthesis. Xylem sap consists mainly of water and inorganic ions, although it can contain a number of organic chemicals as well. This transport is not powered by energy spent by the tracheary elements themselves, which are dead at maturity and no longer have living contents. Two phenomena cause xylem sap to flow:

• Transpirational pull: the most important cause of xylem sap flow is the evaporation of water from the surfaces mesophyll cells to the atmosphere. This transpiration causes millions of minute menisci to form in the mesophyll cell wall. The resulting surface tension causes a negative pressure or tension in the xylem that pulls the water from the roots and soil.
• Root pressure: If the water potential of the root cells is more negative than the soil, usually due to high concentrations of solute, water can move by osmosis into the root. This causes a positive pressure that forces sap up the xylem towards the leaves. In some circumstances the sap will be forced from the leaf through a hydathode in a phenomenon known as guttation. Root pressure is highest in the morning before the stomata open and allow transpiration to begin. Different plant species can have different root pressures even in a similar environment; examples include up to 145 kPa in Vitis riparia but around zero in Celastrus orbiculatus[2].

[edit] Anatomy of xylem

Xylem can be found:

• in vascular bundles, present in non-woody plants and non-woody parts of plants with wood
• in secondary xylem, laid down by a meristem called the vascular cambium in woody plants
• as part of a stelar arrangement not divided into bundles, as in many ferns.

Note that, in transitional stages of plants with secondary growth, the first two categories are not mutually exclusive, although usually a vascular bundle will contain primary xylem only.

The most distinctive cells found in xylem are the tracheary elements: tracheids and vessel elements. However, the xylem is a complex tissue of plants, which means that it includes more than one type of cell. In fact, xylem contains other kinds of cells, such as parenchyma, in addition to those that serve to transport water.

Primary and secondary xylem

Primary xylem is the xylem that is formed during primary growth from procambium. It includes protoxylem and metaxylem. Metaxylem develops after the protoxylem but before secondary xylem. It is distinguished by wider vessels and tracheids.

Secondary xylem is the xylem that is formed during secondary growth from vascular cambium. Although secondary xylem is also found in members of the "gymnosperm" groups Gnetophyta and Ginkgophyta and to a lesser extent in members of the Cycadophyta, the two main groups in which secondary xylem can be found are:

1. conifers (Coniferae): there are some six hundred species of conifers. All species have secondary xylem, which is relatively uniform in structure throughout this group. Many conifers become tall trees: the secondary xylem of such trees is marketed as softwood.
2. angiosperms (Angiospermae): there are some quarter of a million to four hundred thousand species of angiosperms. Within this group secondary xylem has not been found in the monocots. In the remainder of the angiosperms this secondary xylem may or may not be present, this may vary even within a species, depending on growing circumstances. In view of the size of this group it will be no surprise that no absolutes apply to the structure of secondary xylem within the angiosperms.

with the help of XYLEM and PHLOEM present in the tree vascular tissues.

phloem is the innermost layer of the bark ,

StructureMultiple cross sections of a stem showing phloem and companion cells[1]

Phloem tissue consists of less specialized and nucleate parenchyma cells, sieve-tube cells, and companion cells (in addition albuminous cells, fibers and sclereids).

Sieve tubes

The sieve-tube cells lack a nucleus, have very few vacuoles, but contain other organelles such as ribosomes. The endoplasmic reticulum is concentrated at the lateral walls. Sieve-tube members are joined end to end to form a tube that conducts food materials throughout the plant. The end walls of these cells have many small pores and are called sieve plates and have enlarged plasmodesmata.

Companion cells

The survival of sieve-tube members depends on a close association with the companion cells. All of the cellular functions of a sieve-tube element are carried out by the (much smaller) companion cell, a typical plant cell, except the companion cell usually has a larger number of ribosomes and mitochondria. This is because the companion cell is more metabollically active than a 'typical' plant cell. The cytoplasm of a companion cell is connected to the sieve-tube element by plasmodesmata.

There are three types of companion cell.

1. Ordinary companions cells - which have smooth walls and few or no plasmodesmata connections to cells other than the sieve tube.
2. Transfer cells - which have much folded walls that are adjacent to non-sieve cells, allowing for larger areas of transfer. They are specialised in scavenging solutes from those in the cell walls which are actively pumped requiring energy.
3. Intermediary cells - which have smooth walls and numerous plasmodesmata connecting them to other cells.

The first two types of cell collect solutes through apoplastic (cell wall) transfers, whilst the third type can collect solutes symplastically through the plasmodesmata connections.

In vascular plants, xylem is one of the two types of transport tissue, phloem being the other. The word "xylem" is derived from classical Greek ξυλον (xylon), "wood", and indeed the best known xylem tissue is wood, though it is found throughout the plant. Its basic function is to transport water.

Physiology of xylem

The xylem is responsible for the transport of water and soluble mineral nutrients from the roots throughout the plant. It is also used to replace water lost during transpiration and photosynthesis. Xylem sap consists mainly of water and inorganic ions, although it can contain a number of organic chemicals as well. This transport is not powered by energy spent by the tracheary elements themselves, which are dead at maturity and no longer have living contents. Two phenomena cause xylem sap to flow:

• Transpirational pull: the most important cause of xylem sap flow is the evaporation of water from the surfaces mesophyll cells to the atmosphere. This transpiration causes millions of minute menisci to form in the mesophyll cell wall. The resulting surface tension causes a negative pressure or tension in the xylem that pulls the water from the roots and soil.
• Root pressure: If the water potential of the root cells is more negative than the soil, usually due to high concentrations of solute, water can move by osmosis into the root. This causes a positive pressure that forces sap up the xylem towards the leaves. In some circumstances the sap will be forced from the leaf through a hydathode in a phenomenon known as guttation. Root pressure is highest in the morning before the stomata open and allow transpiration to begin. Different plant species can have different root pressures even in a similar environment; examples include up to 145 kPa in Vitis riparia but around zero in Celastrus orbiculatus[2].

[edit] Anatomy of xylem

Xylem can be found:

• in vascular bundles, present in non-woody plants and non-woody parts of plants with wood
• in secondary xylem, laid down by a meristem called the vascular cambium in woody plants
• as part of a stelar arrangement not divided into bundles, as in many ferns.

Note that, in transitional stages of plants with secondary growth, the first two categories are not mutually exclusive, although usually a vascular bundle will contain primary xylem only.

The most distinctive cells found in xylem are the tracheary elements: tracheids and vessel elements. However, the xylem is a complex tissue of plants, which means that it includes more than one type of cell. In fact, xylem contains other kinds of cells, such as parenchyma, in addition to those that serve to transport water.

Primary and secondary xylem

Primary xylem is the xylem that is formed during primary growth from procambium. It includes protoxylem and metaxylem. Metaxylem develops after the protoxylem but before secondary xylem. It is distinguished by wider vessels and tracheids.

Secondary xylem is the xylem that is formed during secondary growth from vascular cambium. Although secondary xylem is also found in members of the "gymnosperm" groups Gnetophyta and Ginkgophyta and to a lesser extent in members of the Cycadophyta, the two main groups in which secondary xylem can be found are:

1. conifers (Coniferae): there are some six hundred species of conifers. All species have secondary xylem, which is relatively uniform in structure throughout this group. Many conifers become tall trees: the secondary xylem of such trees is marketed as softwood.
2. angiosperms (Angiospermae): there are some quarter of a million to four hundred thousand species of angiosperms. Within this group secondary xylem has not been found in the monocots. In the remainder of the angiosperms this secondary xylem may or may not be present, this may vary even within a species, depending on growing circumstances. In view of the size of this group it will be no surprise that no absolutes apply to the structure of secondary xylem within the angiosperms.

The End

Answer 2

Water is held inside a tree in two ways. 'Free Water' is water that is held in the vessels and cells and its purpose is to distribute nutrients inside the tree. 'Cell' water (also known as 'bound' water), is an intrinsic part of the tree's cell walls. During the seasoning process a tree loses its 'free' water and a high proportion of its 'cell' / 'bound' water.Hope it helped!! :)

Answer 3

rain falls and then pours in to plants and into roots the tree has nutrients now