Corolla shapes
Corollas of fused petals have various shapes.
There are several radially symmetrical shapes:
Urceolate corollas are urn shaped, widening rapidly at the base and narrowing toward the tip.
Campanulate corollas are bell-shaped, being rounded at the base then having straight or gradually widening sides toward the tip.
Funnelform or funnel-shaped corollas gradually increase in diameter from the base toward the tip.
Salverform corollas have a fairly abrupt transition between a narrow tube and a distal, flat limb where the corolla lobes spread into a lobed disk or wheel-like structure. The throat of a salverform corolla is the region where the limb meets the tube.
Rotate corollas are like salverform corollas with either no tube or a very short tube. They form a fairly flat wheel-like structure.
Bilateral flowers with 5 fused petals often form a corolla with two lips (bilabiate corollas). Usually the lower lip has three lobes and provides a landing platform for pollinators; the upper lip has two lobes.
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