A farmer shows Ira a pea flower. Its five petals are of three kinds…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
A farmer shows Ira a pea flower. Its five petals are of three kinds. The largest one covers the two side petals, and these cover the two smallest ones. The flower can be cut into similar halves in one plane only. (a) Name the aestivation. (b) Name the three kinds of petal. (c) What kind of symmetry does it show? (d) The stamens are in two bundles. What is this called? (e) Name its placentation.
Need a reminder? The key ideaShow
A flower has the calyx, corolla, androecium and gynoecium. Bisexual or unisexual; actinomorphic, zygomorphic or asymmetric. Hypogynous (superior ovary), perigynous (half inferior), epigynous (inferior). Aestivation: valvate, twisted, imbricate, vexillary. Stamens: filament and bilobed anther with four pollen sacs; epipetalous, epiphyllous, monoadelphous, diadelphous, polyadelphous. Carpel: ovary, style, stigma; apocarpous or syncarpous. Placentation: marginal, axile, parietal, free central, basal.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. The aestivation. It is vexillary.
Step 2. The petals. The large one is the standard. The two side petals are the wings. The two small ones form the keel.
Step 3. The symmetry. Only one vertical plane gives two similar halves, so the flower is zygomorphic.
Step 4. The stamens. They are diadelphous, in two bundles.
Step 5. The placentation. The ovules sit on a ridge along one side of a single chamber, so it is marginal.
Answer: (a) vexillary; (b) standard, wings, keel; (c) zygomorphic; (d) diadelphous; (e) marginal.
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