Corolla

The corolla, made up of petals, is usually the most visually attractive floral whorl in most flowers and is typically brightly coloured; its role is to display the flower prominently and attract pollinators. Petals may stay distinct - an apopetalous (polypetalous/choripetalous) condition, as in Hibiscus - or fuse together into a sympetalous (gamopetalous) corolla, as in Datura. Each fusion condition then has its own named shapes. Among apopetalous, actinomorphic corollas: cruciform has four petals arranged in a cross (Brassica, mustard, radish, cauliflower); caryophyllaceous has five long-clawed petals whose limb sits at right angles to the claw (Caryophyllaceae, Dianthus); rosaceous has five to many sessile or minutely clawed petals with radiating limbs (rose, tea). Among apopetalous, zygomorphic corollas: papilionaceous ('butterfly-shaped') is made of five distinct petals of three kinds - one large posterior standard petal (vexillum), two lateral wing petals (alae) and two smaller anterior petals fused into a keel (carina) - as in Clitoria ternatea, pea and bean. Among sympetalous, actinomorphic corollas: tubular has petals fused into a narrow tube with very short limbs (disc florets of sunflower); campanulate is fused into a bell shape (Physalis, Cucurbita maxima, Campanula); infundibuliform is fused into a funnel shape that gradually widens (Datura, Ipomoea); rotate is fused into a wheel shape with a very short tube and a spreading circular limb (brinjal, Evolvulus); salver-shaped (hypocrateriform) is fused into a long narrow tube with spreading limbs (Catharanthus, Ixora, Tabernaemontana); and urceolate is fused into an urn or pot shape (Bryophyllum calycinum, Diospyros). Among sympetalous, …