Calamus, the name of a plant, was the title given to a group of poems in the 1860 edition of Leaves. The rather phallic-leafed plant may suggest comradeship or "adhesiveness." Whitman was interested in phrenology, a pseudo-science dealing with character as supposedly revealed by a study of skull formation. Adhesiveness is a term used in phrenology to refer to emotional comradeship between men.
The Calamus poems (which Whitman originally thought of calling Live-Oak), thirty-nine in number, are marked by emotional intensity and eloquent expression. They also raise the question of Whitman's life in relation to his poetry.
Whitman makes use of the Calamus as a many-faceted metaphor. It stands for "athletic love" and for varying degrees of attachment between men. Its different connotations arise from the varied levels of the love between comrades — the resilience and depth of that love. Calamus grows in various shapes and forms and its variety accords with the diversity of love between men.