Calyxes form in tight groups during flowering called racemes. The "buds" you see are just collections of swollen calyxes with small "sugar leaves" growing from them.
The main cola, or any cola for that matter is just a collection of calyxes.
In preflowering, you will usually just see a single calyx (female) with two white hairs (pistils) scattered about the plant where stems intersect with branches.
The pistils grow from the tip of the tear drop shaped calyx. They are there to receive pollen from the male plant. Once pollinated, the pistils die and shrivel and a seed begins to grow in the seed bract (calyx) If not pollinated, the pistils eventually turn orange/brown and shrivel and the calyx swells as if it has a seed in it.
Trichomes (THC containing glands) grow most densely on these swollen calyxes and the small surrounding sugar leaves.