We recognize three kinds, or shapes, of calyx tubes; namely, the cone-shaped, the funnel-shaped, and the urn-shaped.

Cone-shaped calyx tube. A calyx tube resembling, or conforming to, the general shape of a cone.. Funnel-shaped calyx tube. A calyx tube whose general shape resembles that of a funnel, or which has a little tube attached to the base of the cone-shaped tube. Urn-shaped calyx tube. A calyx tube resembling an urn in shape, or having sides which are neither straight nor funnel-form, but which have a double curve and are comparatively broad and rounded toward the base.