The tumors appear as discoid prominences of varying size and number.
The radiate type is shown by discoid infusoria, by medusæ, by starfish and their allies.
Anterior above with a small, linear-oval, black, discoid spot.
Heads discoid, 15–many-flowered, in corymbose cymes; flowers perfect.
The tubular flowers compose the disk; and a head which has no ray-flowers is said to ...