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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/Leaf8/3/2019 SBC chap 7.4_7.5
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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=S8/3/2019 SBC chap 7.4_7.5
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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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