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7.4 C3 and C4 plants

2 Types of plants according to carbon fixation

in photosynthesis:

1. C3 pathway= C3 plant

2. C4 pathway=C4 plant

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C4 Leaf Anatomy

The C4 plants possess a characteristic leafanatomy. Their vascular

bundles are surrounded by two rings of cells. The inner ring, called

Bundle Sheath Cells, contain starch-rich chloroplastslacking grana

which differ from those in mesophyll cells present as the outer ring.

This peculiar anatomy is called Kranz Anatomy (Kranz-

Crown/Halo).

The primary function of the Kranz is to provide a site in which

carbon dioxide can be concentrated, thus reducing photorespiration.

In order to facilitate the maintenance of a significantly higher carbon

dioxide concentration in the bundle sheath compared to the

mesophyll, the boundary layer of the Kranz has a low conductance

to carbon dioxide, a property which may be enhanced by the

presence of suberin.

http://en.wikipedia.org/wiki/Leafhttp://en.wikipedia.org/wiki/Starchhttp://en.wikipedia.org/wiki/Chloroplasthttp://en.wikipedia.org/wiki/Mesophyllhttp://en.wikipedia.org/wiki/Mesophyllhttp://en.wikipedia.org/wiki/Chloroplasthttp://en.wikipedia.org/wiki/Starchhttp://en.wikipedia.org/wiki/Leaf

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Kranz anatomy

A specialized leaf anatomy found in C4 plants,where the vascular bundle sheath comprises 2

concentric layers around the vascular bundles.Outer layer of large mesophyll cells that oftenradiate out from the bundle sheath and containa greater abundance of often largerchloroplasts than usual cells and inner layer ofbundle sheath = mestome sheath.

http://ecoport.org/ep?searchType=glossaryShow&glossaryId=27562&viewType=Shttp://ecoport.org/ep?searchType=glossaryShow&glossaryId=10466&viewType=Shttp://ecoport.org/ep?searchType=glossaryShow&glossaryId=3579&viewType=Shttp://ecoport.org/ep?searchType=glossaryShow&glossaryId=3579&viewType=Shttp://ecoport.org/ep?searchType=glossaryShow&glossaryId=10466&viewType=Shttp://ecoport.org/ep?searchType=glossaryShow&glossaryId=27562&viewType=S

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7.5 Petiole Anatomy

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Anatomical characteristic of petiole Tissue of petiole may easily compared with the primary tissue

of the stem as tere is a close similarity between them with

regards to their structure of epidermis The supporting tissue is collenchyma or sclerenchyma

The vascular bundles may be collateral or concentric

The petiole does have the structure of epidermis, hypodermisof collenchyma, ground tissue and vascular system or

complex. The arrangement or pattern of the vascular bundles are vary

among species and also vary according to where the petiolesection is made

Usually for the purpose of comparative anatomy in systematic

the petiole sections are made at the half way from the base tothe starting of the blade (middle), at the base of the petiole ornear to the blade and arrangement of the vascular system willbe observed. The outline of the petiole will also has taxomicvalue: concave, convex, ridged etc.

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Plants which characteristically grow in certain

ecological niches and show a type of structure

which is believed to adapted to that particular

environment.

This type of adapted structural anatomy due to

the environment = ecological anatomy.

7.5 Ecological Anatomy

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Hydrophytes: plant live wholly or partly submergedin water or very wet place

Mesophytes: plant live in habitat that shows neitherexcess nor deficiency of water, average temperatureand moisture

Xerophytes: plants grow at dry habitat whereevaporation stress is high and the water supply is low

Halophytes: plants that grow in saline soil or water

Epiphytes: plants that grow upon other plants, but donot absorb food from the host

Parasite: plants that grow upon other plants andabsorb food from the host

Saprophytes: plant that leave on decaying organicsubstances

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