So overall, very well done. I'm seeing a great deal of improvement in solving the issues I pointed out previously, especially about not adhering to previous steps of the construction. Just a few comments, then I will get on to answering your questions.

Leaves

I'm seeing a lot of fluidity in your leaves now, which is awesome. The only thing I would ask you to experiment on (aside from complex leaf structures), is wider leaves. You'll find them more difficult to get flowing, but more difficult also means more reason to practice them.

Regarding the edge detail, what you have done is pretty well done. One improvement I can suggest: where the edge detail runs along the previous simple edge, don't draw it again, instead, just leave the previous simple edge there.

Constructions

Very solid plant constructions. The only things I want to talk about are the last plant (Page 11 plant 2) and the plant you were having trouble with (Page 10 plant 2).

• For the last plant, you seem to have omitted the central flow lines for the leaves. Looking at references I understand that these leaves are somewhat stiff in nature (though not entirely), but you should still draw the central flow line. I would also draw a larger, more traditionally shaped leaf for the simple edges, and then cut off the top part of the leaves (the part where the leaf starts to get narrower) to produce the triangular shape, but I'm not entirely sure if that's the right approach.

• For Page 10 Plant 2, I've put together a small demo to show how I would approach it. I've drawn it in pencil because right now I'm still far more comfortable with that than anything else (though it should still work pretty well in fineliner), and I'm still very much learning myself, but hopefully this helps: https://imgur.com/a/3x3J6QI.

I think the major way to improve would have been to approach constructing the petal through the complex leaf construction method, while I see multiple flow lines, you didn't actually draw the simple curves around those flow lines, meaning that you lost the actual flow of those lines in the next construction step.

As for capturing the folds themselves, note that folds really aren't that different from any other edge detail. If you wanted, you could capture the actual folding on the surface through a few texture cast shadows, but for now just showing how the folds change the edge should be good enough.

Questions

Regarding texture, it's important to understand the goal of adding texture. The goal is not to decorate the drawing, or to make it look good. Instead, it is to capture the small forms running along the surface of the object, to give the viewer a sense of how it feels. To do this, you can only draw the cast shadows of the forms. However, there is no requirement to capture all of the forms you see, as you can guess, some textures can get incredibly complex, leading to a lot of cast shadows. The goal is to use the idea of texture gradients, like from lesson 2, to capture only enough texture to give the viewer the impression of how the surface feels (and since gradients require capturing cast shadows, this is why only drawing the cast shadows is important). Ultimately, it's up to you how much texture you want to capture, just remember that a lot of complexity tends to be a focal point, so avoid capture lots of texture in places that you don't want the viewer's eye to be attracted to.

I'm not entirely clear on what you mean when you say ellipses confuse you, but I will try to give a general explanation of how it works. So a lot of flowers have petals that, if you look at them from above, would form a circular shape. This is just a consequence of every petal being roughly the same shape and size, and coming from the same place, so naturally they all end at the same distance from the center. To capture this idea, you can draw a circle, this saves you from having to try to have all the flow lines ending the same distance from the center. Of course, in order for this to work, you need to later draw the flow lines to this circle, otherwise, your petals aren't going to end at the same distance anyways.

An ellipse is just a circle in 3d space, so with an ellipse, we can draw such a flower looking at it from any angle, not just directly from above.

Regarding cast shadows vs form shadows, the key difference is that cast shadows are always cast by another object onto the surface. Whenever you want to draw a shadow, think about what object is causing that shadow, if it's the same object, then it's a form shadow. If it's different, then it's a cast shadow. I understand the distinction can get difficult in certain situations, but that's just a matter of practice. As to how to capture cast shadows precisely, I believe that's just a matter of understanding form better. Understanding form is a goal of this entirely course, so naturally this will be improved as you work through the other lessons.

Anyways, there's plenty of good work here, so I believe you are more than ready to move on to the next lesson. Good luck!