Apple: healing and love.

Cherry: death and rebirth; new awakenings.

Flowering Almond: hope.

Holly: death and rebirth; protection; overcoming of anger.

Oak: Independence; bravery; protection, strength, stability, endurance, continuity.

Poplar (Genus Populus; Lombardy Poplar, Cottonwood): ability to endure and conquer; courage.

Aspen (other species of Populus, including Quaking Aspen): determination; overcoming fears and doubts.

Elder (as in elderberry; Genus Sambucus): "indicates the end in beginning and beginning in end; Life in Death and Death in Life".

Cedar: healing, cleansing, protection.

Beech: prosperity.

Cypress: sacrifice (I would use this to dedicate plantings for the over 300 rescue workers lost in the collapse).

Andromeda: self sacrifice (another plant to honor fallen rescue workers).

Arbor Vitae: unchanging friendship

Spruce: hope in adversity.

Elm: strength of will; patriotism.

Pine: balance of pain and emotions.

Geranium: healing, happiness, renewed joy.

Hyacinth: overcoming of grief; gentleness.

Nasturtium: patriotism

Rose: love, strength through silence. White and red roses together signify unity.

Rosemary: remembrance

Rudbeckia: justice

Sweet William: gallantry