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PLANT MAGAZINE

THE PLANTS:

FLOWERS

STEMS AND BUDS

FRUITS

ROOTS

SEEDS

GLOSSARY

The leaf  

 

THE LEAF : TYPES

According to the petiole:

Petiolated (Stalked)


Sessile. (Unstalked)

Petiolated leaves are those that have a petiole. This can be different in length from one plant to another.

Sessile leaves do not possess a petiole. The blade expands itself directly from the stem.


According to the blade:

Simple leaf

Compound leaf

Simple leaves show an undivided blade or , in case it has divisions, they do not reach the midrib.

Compound leaves have a fragmented blade,with divisions reaching the midrib. Sometimes each one of these fragments is similar to a single leaf. They are called leaflets.


According to the edge:

Entire

Sinuate

Dentate

Serrate

Lobed

Entire leaves have a smooth margin.

Sinuate leaves have little curves with smooth edges like waves.

Dentate leaves have little teeth at the margin.

Serrate leaves have little bent teeth like those of a saw.

Lobed leaves have divisions that do not arrive the center of half blade.


According to the shape of the blade:

elliptic

lanceolate

acicular

ovate

cordate

Hastate

linear


Elliptic leaves : remembering to a ellipse. 2 or 3 times longer than wide

Lanceolate leaves : spear-shaped. Gradually extending at the base and lessening to the apex.

Acicular leaves : needle-shaped. Several times longer than wide; ending sharply at the apex.

Ovate leaves : egg-shaped. Wider at the base than the apex.

Cordate leaves : heart-shaped . More extended at the base than the ovate type and with a notch

Hastate leaves: halberd-shaped. Remembering to that old fashioned weapon which was a combination between a spear and a battle-ax. Wider at the base but with lobes ending sharply.

linear leaves: strip-shaped. Several times longer than wide. Not pointed at the apex like in the acicular type.


According to the veins:

Parallel-veined

Pinnate

Palmate

Parallel-veined leaves : the veins run at the same distance to each other, like in canes.

Pinnate leaves : There is a main nerve, called midrib, from which the other nerves derive, remembering a plume.

Palmate leaves: The nerves diverge from the main point such as the fingers do in the palm of the hand.


According to the arrangement along the stem:

alternate

opposite

whorled

rosulate


alternate: springing one per node at different levels of the stem.

opposite: two per node, facing opposite sides of the stem.

whorled: Several leaves disposed at the same level around the stem.

rosulate forming a rosette, like a ring around the stem.


Do the following activities before the test:
     
     
Now you can do the test:

 

Observe the following plants and choose the suitable answer in each case:

How would you define the leaves of the heather according to the blade?

-Simple

-Petiolated

-Compound

How would you define the poppy leaves according to the margin?

-Lobed

-Dentate

Sinuate

How would you define the mint leaves according to the nerves?

-Palmate

-Parallel-veined

-Pinnate

How would you define the daffodil leaves according their arrangement along the stem?

-whorled

-Opposite

-Rosulate













 

 

 

 

 

 

 

 

 

 

 

 
















 

 

 

 

 
 

 

 
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