Vrksasana :: TREE

from a standing position in tadasana (mountain pose) bring the weight into the right foot. root the foot into the earth, lift the left foot and place on the right ankle. find a drishti (focal point) in front of you and slowly begin to bring the left foot to place on the calf or inner thigh -- being sure to avoid placing the foot on the knee. with hands at Anjali mudra (heart center) find stability by pressing the foot against the thigh as you create an equal and opposing energy by pressing the thigh against the foot. maintain the rootedness in your trunk as you extend the arms and reach up to grow your tree branches. 

hold this balance as long as desired while continuing with your breath and focus. 
release the foot and repeat on the other foot.

•activates stability
•ignites inner core
•increases balance
•strengthens the solar plexus chakra
•relieves sciatica and reduces flat feet

modifications : 
•leave the foot placed at the ankle
•use the wall (or a tree) for support
•place foot in half padmasana (lotus)

be careful of:
•low blood pressure
•high blood pressure