Leaf structures

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Slide 16

Phyllotaxy

It is the mode of arrangement / distribution of leaves on stem or it’s branch.

Phyllotxy ensures that leaves may receive maximum sunlight for photosynthesis.

Slide 17

Alternate Phyllotaxy

In such case only one leaf is attached at each node. The leaves are so arranged that a line drawn on the stem through the leaf bases will take a spiral course. Ex. Hibiscus, Brassica etc.

Slide 18

Opposite Phyllotaxy

In such case two leaves are present at each node, standing opposite to each other. It is of two subtypes -

Opposite decussate

Opposite superposed

Slide 19

Opposite Decussate

Here pairs of leaves at each successive node are placed at right angle to each other. Eg. Ocimum, Calotropis etc.

Slide 20

Oposite Superposed

Here pairs of leaves at each successive node are placed over each other in same plane. Eg.Eugenia,Quisqualis etc.

Slide 21

Whorled Phyllotaxy

In this type more than two leaves are present at each node, forming a whorl. Ex. Oleander, Alstonia etc.

http://www.umanitoba.ca/faculties/science/biological_sciences/lab10/biolab10_4.html#Structure