Drawing Power from Trees  

gaiamoon.blogspot.com/2010/12/dark-goddess-Hekaté

Spell thanks to James Kambos. The spell is edited by me for specific reasons mentioned below. Feel free to add my additions to your version of the spell if you so desire, or add your own. Do this as you feel led by the Spirit of the Tree you have chosen because He/She has also chosen you. 

"Trees are ancient beings. They are keepers of the life force. They receive nourishment from Mother Earth and Father Sun." -- James Kambos.

To gain power from a Tree and to receive the same magickal energy which they possess, perform the following spell: 

Be sure to cast a Circle around yourself and the Tree before doing the spell.

01) Remove three hairs from your head and tie them together with ordinary garden twine.

02) Go to a wooded area where you won’t be disturbed. Walk around until you find a tree you’re attracted to. [Or: if the desired Tree is in your yard then choose that Tree. The closer the Tree is to you, the better in my opinion.]

03) The Tree should represent the powers you’re looking for - e.g., a Willow Tree for healing/protection; an oak tree for strength, etc. From my personal workings with Willow Trees is that they are perfect for Wisdom-related spells.
  Although the author of this spell (James Kambos) does not mention Willow and Wisdom in the same sentence, I would strongly recommend placing the hair on a Willow Tree for Wisdom purposes since all Trees are filled with Ancient Wisdom.
  The Willow is a Tree of the Moon and Hekaté and thus the Willow is connected to the Two Sources of eternal Wisdom.

04) Tie your bundle of hair to a longer piece of twine. Wrap the twine about the tree trunk and tie as you say the following:

With hair and twine,
my strength (substitute with desired need) is yours,*
and your strength is mine.

*Substitute "power" with desired need - e.g., Wisdom, healing, love, fertility, etc.

05) You and your sacred tree are now bound, from toe to crown.

06) As an addition to "binding" yourself to your chosen Tree, I would suggest taking a piece of bark (small enough to carry with you) from the Tree.  
This will symbolize your bond and the ever-present presence and power of the Tree with you. Be sure to leave an offering before taking the bark. This will increase your relationship with the Tree.
Always ensure to give offerings whenever possible, or when you feel led to do so.

Respect for the Trees are above all most important.

Finding the right Tree for the Spell need: 

Alder: Completeness, Spirituality

Apple: It symbolizes living life to the full, focusing mind and heart together positively

Ash: Prosperity, Protection, Healing

Aspen: Intuitive knowledge, understanding

Beech: Inspires us to let go of old patterns, to see more of the good that is in the world

Birch: Protection of Children, Purification

Blackberry Vines: Prosperity, Protection, Healing, Inspiration

Blackthorn: Cleansing and renewal, leading to a sudden, spontaneous flowing of the spirit.

Cedar: Release from the unwanted, purification, renewal

Cherry: Success, productivity

Dogwood: To distinguish between, to see beyond, spiritual inspiration

Elder: Exorcism, Prosperity, Banishing, Healing

Elm: Mystery, home to the elven folk, encourages renewed faith in the value of our life's work

Eucalyptus: Transformation, kindness, transmutation

Fir: Ancient wisdom, regeneration

Fire Maple: Intense energy

Gorse: Aura of contentment, fulfillment, optimism.

Grape Vines: Fertility, Inspiration, Prosperity, Binding Spells

Hawthorn: Fertility, Peach Prosperity

Hazel: Manifestation, Protection, Fertility

Heather: Reviving and soothing Holly: Protection, Prophecy, Magick for Animals

Ivy: Healing, Protection, Cooperation, Exorcism

Maple: luck, strength, family

Oak: All Positive Purposes

Pear: Hope, generosity, inner growth

Pine: Ancient wisdom, eternal life

Poplar: Vision, peace

Redwood: Long memory, strength

Reed: Fertility, Protection, Love

Rowan: Healing, Empowerment

Willow: Love, Healing, Protection, Fertility 

May the divine Spirits of the Ancient Trees be with you.
Blessed be