In general, the elementals of trees tend to adhere to the following rules:
The elemental of tall trees (and occasionally trees with low density wood) tends to be Air.
The elemental of hot climate trees, trees with red berries, trees with reddish wood, or trees with bright red, orange, or yellow autumn leaves tend to be Fire.
The elemental of short trees or trees with high-density wood tends to be Earth.
The elemental of trees that grow in very moist conditions tends to be Water.
The following list summarizes the elementals, phases, and genders associated with each magical wood commonly used in the making of magic wands.
Alder - Elementals: Water; Phases: Light and Darkness; Gender: Male
Apple - Elementals: Quintessence, Fire, and Earth; Phase: Light; Gender: Female
Ash - Elementals: Air , Fire, and Earth; Phase: Light; Gender: Male
Birch - Elementals: Quintessence and Earth; Phase: Light; Gender: Female
Blackthorn - Elemental: Earth; Phase: Darkness; Gender: Male