Zygomorphy in Cassia flower is due to

A flower which can be divided into equal vertical halves by more than one plane of division is

An example of axile placentation is

Placentation in tomato and lemon is

Differentiate between :

$(a)$ Bract and Bracteole

$(b)$ Pulvinus and Petiole

$(c)$ Pedicel and Peduncle

$(d)$ Spike and Spadix

$(e)$ Stamen and Staminoid

$(f)$ Pollen and Pollenium

When the margins of sepals or petals overlap one another without any particular direction, the condition is termed as