whorl

Photograph and axial plane floral diagram of Friesodielsia desmoides, showing the whorled pattern of multiple concentric objects. Leaf whorls on a herbaceous Lilium michiganense Leaf whorls on a woody tree, Brabejum stellatifolium In botany, a whorl or verticil is a whorled arrangement of leaves, sepals, petals, stamens, or carpels that radiate from a single point and surround or wrap around the stem or stalk. A leaf whorl consists of at least three elements; a pair of opposite leaves is not called a whorl.

For leaves to grow in whorls is fairly rare except in plant species with very short internodes. Genera with species having whorled leaves include Galium, Nerium, Elodea, and Lilium. Leaf-like bracts may also be whorled (as in Trillium, e.g.). Leaf whorls occur in some trees such as Brabejum stellatifolium and other species in the family Proteaceae (e.g., in the genus Banksia). In plants such as these, crowded internodes within the leaf whorls alternate with long internodes between the whorls.