Transport in plants 1

Transport in Plants

L/O to be able to describe, with the aid of diagrams andphotographs, the distribution of xylem andphloem tissue in roots, stems and leaves of

dicotyledonous plants;

Plant

Stem

Role of the stem

• Support – hold leaves in place for sunlight• Support – hold flowers in place for pollination• Movement of materials from leaves to other

parts• Movement of water in stream from the roots

to leaves. Also move ions.• Are green and carry out a small amount of

photosynthesis

The Three Tissue Systems

Dermal Tissue – plant’s protective covering in contact with the environment

Vascular tissue – this tissue conducts water and solvents between organs and provides mechanical support

Ground tissue – packing and supportive tissue accounts for much of the bulk of the young plant

Cross section of a stem

Vascular Tissue• Xylem and phloem conducting elements are associated with parenchyma

cells• Phloem – transports organic solutes (sucrose) in the plant• Have lost their nuclei and much of their cytoplasm• Actively transport soluble food products into and out of sieve tube

elements

Vascular Tissue - Xylem

• Carries water and dissolved ions in the plant• Dead cells at maturity that lack a plasma

membrane• Cell wall has been secondarily thickened and

lignified (lignified tissue called metaxylem)• Enables very long continuous tubes to be

formed

Vascular bundle...

Notes pgs 68-69...• Give the functions of xylem, phloem,

meristem, cambium, vascular bundle

xylem

phloem

Definitions• Cambium - A cellular plant tissue from which phloem, xylem, or

cork grows by division, resulting (in woody plants) in secondary thickening

• Vascular Bundle - A strand of conducting vessels (transport tissue) in the stem or leaves of a plant, typically with phloem on the outside and xylem on the inside.

• Meristem - A region of plant tissue consisting of actively dividing cells forming new tissue

• Phloem - The vascular tissue in plants that conducts sugars and other metabolic products upward and downward between the leaves and root.

• Xylem - The vascular tissue in plants that conducts water and dissolved nutrients upward from the root and also helps to form the woody element in the stem

Summary...

• The vascular tissue in a leaf forms a network of bundles that finally merge to form one central (1) which runs into the stalk of the leaf that is also called the (2). The vascular tissue found nearest to the upper surface of the leaf is (3). In stems, the vascular tissue nearest the outside of the stem is (4). Inside this tissue is a layer of dividing tissue called (5) and outside it there is often a region of supporting tissue called (6). The vascular tissue in stems forms a cylinder towards the outer edge as this arrangement best resists the (7) forces that stems are subjected to. In roots, the vascular tissue is central in order to resist the (8) forces experienced by the roots.

Missing words…

1. Vein2. Midrib3. Xylem4. Phloem5. Cambium (meristem)6. Parenchyma7. Shearing/bending8. Pulling