On the module of XYLEM & PHLOEM

In plants different parts absorb water and send it to all parts of the plant.

The tissue that is involved in the transportation of materials is vascular tissue.

The main components of vascular tissue are Xylem and Phloem.

Xylem mainly consists of dead elements where as Phloem consists of living elements .

In some plants they carry water to great heights in the plant body i.e. up to nearly 330ft.

It gives mechanical support to the plant.

Introduction

Xylem is one of the two types of transport tissue in vascular plants.

This word XYLEM derived from the Greek word Xylon (ξύλοv) which means “wood”.

The best known Xylem tissue is wood, that is found through out the plant.

It’s basic function is to transport water, but it also transfers some nutrients through the plant.

Vessels and trachieds are responsible for the conduction of water and minerals.

XYLEM

Pholem is the vascular tissue which carries organic nutrients like photosynthane.

As the Pholem is the inner most layer of the bark its name is derived from reek word philos.

It mostly transports soluble organic material made during photosynthesis. This is called translocation.

Phloem Sieve tubes are responsible for the conduction of organic minerals to all parts of the body.

PHLOEM

Xylem and Phloem

PHLOEM XYLEM Transports food and

nutrients like sugar and amino acids.

Bidirectional (Moves up or down the plant’s stem from source to sink.

Present in roots, stem and leaves.

Living tissue with little cytoplasm but no nucleus.

Phloem is not star shaped.

Transports water and minerals from roots to aerial parts of plant.

Unidirectional (Moves up the plant’s stem)

Present in roots, stems and leaves.

Dead tissue at maturity so it is hallow with no cell contents.

Xylem. is star shape

Differences & Comparision

Unlike xylem, the phloem is composed of still living cells that transport sap.

The sap is water based solution, but rich in sugars.

These sugars are transported to non-photosynthetic areas like rots, or into storage structures.

A hypothesis was proposed by Ernst Munch in 1930 called Pressure flow hypothesis that explains the mechanism of phloem translocation.

Functions of phloem are…

Its main function is to transport water and soluble minerals from the roots through the plant.

It is also used to replace water loss during transpiration and photosynthesis.

Xylem sap consists mainly of inorganic ions and water, although it consists of many organic chemicals.

The transport is passive, not powered by energy.

Functions of Xylem

Transportation of materials