so you want to know how to draw any flower? well its sorta simple as they use basic shapes and structures. So as long as you know how to draw basic shapes then you are more then set.
The leaf structure is a bit overwhelming at first but I promise it is not. the leaf is composed of the blade (the leaf itself) and there are a few parts to it such as; the veins, margin (leaf outline), and the tip (apex). So long as you keep these key features in mind; you will be fine for more simple designs. anything more detailed you would ad the axillary bud, stipules, and or another stalk that buds into a flower.
There are many types of leaves as there are as many biomes of earth. Some leaves are thin due to harsh environments. Just as some are as large and soft looking like a pillow in calm and stable environments.
some blades are shaped like the sails of ships. these are usually found where there is lots of sunlight.
some leaf blades are shaped like arrowheads, usually found in forest that have moisture.
The most common leaf tips are acute (pointed). However if you do want to diversify your library of leaves, use some of these other apexs.
Some leaf tips split off into two or more apexes, or they can be tapered off as if they been cut.
Again the most common end would be the acute, however dont be afraid to draw these other variations of leaf bases.
The leaf margin is just the outer edge of the blade. Not every leaf is a straight edge like the entire; they do have variations. Some are sawtoothed.
Some margins are rounded, or digited like fingers.
Also not every leaf is flat; some curl in or out of itself, as well as form a cup like shape.
leaf venations mean the texture of the veins and secondary veins of the leaf.
leaves usually face one of three directions, upright, flat, or down.
leaves also have different types of arrangements besides growing from a simple stalk. some form around a pod, such as an opposite decussate. Or form an x pattern with an equitate formation.
Some even grow up in a chain like cord of lights, or form a bundle of needles.
Trifoliate means three. Pinnate means the leaves are spaced out opposite of each other, but they can alternate.
Bipinnate are just pinnate formations that make up a larger pinnate formation. Digitate means shaped like a hand, hence the digit as in the digits of the fingers.
Leaf habits differ; not all plants are in the erect (upwards) formation. Some snake away from the ground, or sprawl out. Some even climb up or downwards depending on where its growing from. So dont be afraid of changing it up.
The round parts is the head or bud of the flowers. (the actual flowers themselves). These are the many common formations of them.
The flower itself seems overwhelming but its not. Its three main shapes are the calyx (sepals or the support leaves after it buds. it also protects the head when it is developing), the petals (corolla) and the Pistil.
Flowers face one of three directions; erect (upright), nodding (slumped), and pendant (downwards)
Flowers come in many different shapes such as star, saucer, bell, and pitcher. these are the most common formations of flowers.