Question

what is the size, venation and arrangement of hibiscus leaf on a branch

Answer 1

Hibiscus leaves sprout from stems at different intervals. If observing a cutting, notice that every leaf is growing at a slightly different height on the stem from the others. As a rule, a healthy hibiscus plant produces three leafs at each growth site on a stem. The plant produces downward-bending leaves while growing, regardless of the amount of water it receives. Juvenile and mature hibiscus leaves look different because they change shape as they mature. This is dimorphic growth.
Leaf Shape
Every hibiscus leaf's shape is predetermined and established in the seed embryo. Once emerging from the stem, hibiscus leaf buds take the form of two, round lobes. The lobes merge as the leaf matures. When fully formed, it resembles a heart, which is why horticulturists refer to the hibiscus leaf as cordate shaped. Even as a bud, a hibiscus leaf is identified by its crenate, a leaf margin that produces an edge that's etched like teeth. This is called a notch.
Leaf Unfolding Rate
It takes about seven weeks for a hibiscus leaf to mature on the stem. Although temperature may slightly alter the rate at which leaves unfold, all of the leaves on a plant unfold at the same predictable and uniform rate. For that reason, a plant or bush that appears to be a member of the hibiscus family but has leaves unfolding at different rates, is a different species of plant.