Lesson 8 of 13 · 9 min
Calyx, corolla and aestivation
NCERT §5.5.1.1, §5.5.1.2, Figure 5.11
Nithya slices across a fat china rose bud and a pea bud with a razor and looks at the cut ends. In the china rose the petals wind round in one direction like a pinwheel; in the pea the biggest petal wraps around all the others.
The lesson in notes
In short
Calyx: the outermost whorl, made of sepals. Sepals are usually green and leaf-like and protect the flower while it is a bud.
Gamosepalous: sepals united. Polysepalous: sepals free.
Corolla: made of petals, whose bright colours usually serve to draw insects in for pollination. Gamopetalous: petals united. Polypetalous: petals free.
Corolla form varies a great deal. Common shapes: a tube (tubular), a bell, a funnel, or a flat wheel.
Aestivation is the way sepals or petals lie in the bud relative to their neighbours in the same whorl. Main types: valvate, twisted, imbricate, vexillary.
Valvate: neighbouring members just meet at their edges and do not overlap. Example: Calotropis.
Twisted: each member overlaps the next one with one margin, all the way round in one direction. Examples: china rose, lady's finger, cotton.
Imbricate: the margins overlap, but with no single direction. Examples: Cassia, gulmohur.
Vexillary or papilionaceous (pea, bean): five petals; the largest, the standard, overlaps the two lateral wings, and the wings overlap the two smallest anterior petals, the keel.
Simulations in this lesson
Each on its own page
In past papers
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