Pepal
A floral diagram illustrates:
Key floral whorls – \(\text{calyx}\), \(\text{corolla}\), \(\text{androecium}\), and \(\text{gynoecium}\) – are depicted in concentric circles from outermost to innermost.
The combined perianth (outer floral envelope) comprises undifferentiated \(\text{sepals}\) and \(\text{petals}\). When these structures are morphologically similar, each unit is termed a \(\text{tepal}\) – the correct designation for the floral elements shown in the diagram.
A tepal is a part of a flower's perianth, which is the outermost whorl of floral structures. The perianth consists of petals and sepals, which can sometimes be indistinguishable in certain plants. When petals and sepals are similar in appearance, they are collectively called tepals.
In the given graph, \( E_a \) for the reverse reaction will be