Water has the property of cohesion and adhesion. Cohesion provides the property of water to get attached with other water molecules and it holds water molecules together, adherence provides the property of stickiness to any surface to the water molecule.
These two properties together allow water molecules to move upwards against gravity. Water moves by capillary action through the water column. Cohesion and adhesion create a pull on the column which transport the water towards the leaves from where they get evaporated.
This evaporation then causes tension on another water molecule and this tension then pulls another water molecule towards leaves.
