Why Aren't Leaves Sweet Despite Containing Sugar from Photosynthesis?

[gfd43tg]

So I was thinking, in the process of photosynthesis

$CO_{2} + 6H_{2}O \xrightarrow{light} C_{6}H_{12}O_{6} + 6O_{2}$

Where is the glucose being deposited in the leaf tissue? Also, why aren't leaves sweet if I were to eat them, considering they are making sugar!

 

[Simon Bridge]

The glucose gets burned as energy to help the plant grow.
Excess glucose is stored int he leaves and other parts of the plant as starch: think where potatoes get all that starchy goodness from?
Glucose is transported around the plant in sap - think: Maple syrup.
Some leaves do taste sweet. But generally plants don't want animals eating their leaves and sap and so on, so they add other stuff to them to make them taste bad and maybe make them poisonous.

 

[Torbjorn_L]

So I was thinking, in the process of photosynthesis

$CO_{2} + 6H_{2}O \xrightarrow{light} C_{6}H_{12}O_{6} + 6O_{2}$

Where is the glucose being deposited in the leaf tissue?

Intriguing question.

First I note that the anabolic carbon from photosynthesis isn't all destined to become C6 sugars. It starts out as phosphated C3 sugars:

The Calvin cycle, Calvin–Benson–Bassham (CBB) cycle, reductive pentose phosphate cycle or C3 cycle is a series of biochemical redox reactions that take place in the stroma of chloroplasts in photosynthetic organisms. It is also known as the light-independent reactions.

Hexose (six-carbon) sugars are not a product of the Calvin cycle. Although many texts list a product of photosynthesis as C₆H₁₂O₆, this is mainly a convenience to counter the equation of respiration, where six-carbon sugars are oxidized in mitochondria. The carbohydrate products of the Calvin cycle are three-carbon sugar phosphate molecules, or "triose phosphates," namely, glyceraldehyde-3-phosphate (G3P).

Then there is the RuBP regeneration:

Thus, of six G3P produced, five are used to make three RuBP (5C) molecules (totaling 15 carbons), with only one G3P available for subsequent conversion to hexose.

[ http://en.wikipedia.org/wiki/Light-independent_reactions#Calvin_Cycle]

I don't know how sweet C3 sugars are, and if cells would chose to export them. Obviously the mitochondria expects hexoses rather than trioses, so the internal cellular use would rely on C6 production.

I think Simon's response covers the rest of this.