You've definitely got a good deal of energy and flow driving your arrows, which carries over for the most part into your leaves. A lot of students have a tendency to stiffen up their leaves, as they focus on how they're finally drawing something solid and tangible, but you're still doing a reasonably good job of maintaining that sense of fluidity here. I did notice however that your leaves do feel somewhat small, and I feel you'd benefit from drawing them larger, taking advantage of the space you have on the page to further engage both your brain's spatial reasoning abilities, and your whole arm while drawing.

You've got a good start with the branches exercise, though you've definitely got a lot of little visible tails where we want to aim to have the segments flow seamlessly into one another. One thing that can help when practicing this is to force yourself to use the last bit of the previous segment as a runway for your next stroke. That is, overlapping it directly before shooting off towards your next target, instead of ignoring it and drawing the following mark where the previous one ought to have been. This forces you to contend with what had happened previously, which will allow you to improve more quickly.

I think overall there's a lot of signs that you're employing the principles covered in the lesson fairly well, but that there's merely a lot of room for growth and improvement. There are a few specific things I want to address, however:

On this page, you definitely ended up drawing very small, not taking up as much of the page as you could have, and leaving the majority of it blank. In doing so, you ended up stiffening up more than in other drawings. You likely drew more from your wrist (given that it's much easier to end up doing that when drawing smaller), and as a result there's a lot more rigidity to your linework. Always be sure to draw large, as you've done on other pages.

Another point I wanted to mention in regards to this drawing are the many lines you drew along the length of each petal. It seems to me that this is detail/texture that you're trying to capture, but you're doing so by employing line rather than the shadow shapes we explored back in lesson 2's texture section. You do this in a number of places, in fact, such as outlining the pebbles at the base of this cactus, and doing effectively the same thing with the little nodules along the cactus' surface. It's true that you didn't outline some of them entirely, which is moving in the right direction, but you didn't treat it as though you were drawing the shadows they cast - instead you were just drawing a line that stopped. When dealing with texture and detail, don't think in terms of line. You're not drawing these elements directly, you're implying their presence by drawing the effects they have on their surroundings.

Here you've got a lot of great fluidity and flow to your lines, though you also have a tendency to go back over your marks in a manner that appears more instinctual and reflexive, rather than demonstrating the kind of control and forethought that we want to see here. Make sure that you're not allowing yourself to draw any marks without applying the ghosting method - every single mark needs to be planned and considered, and nothing should be drawn by instinct.

In this drawing, the main thing that causes it to fall apart is that you start thinking more in terms of the idea that you're drawing lines on a page. Instead of working with lines, what we're doing here is creating individual, solid, three dimensional forms within a 3D world. Nothing exists as a free-floating line, every line is merely a tool to help enclose an area of space to create a form. Therefore if you've got lines flying off on their own, there's definitely something wrong.

All in all I do think that you're moving in the right direction, and that while there's plenty of room for growth, that will come with practice. As such, I'll go ahead and mark this lesson as complete, but be sure to keep what I've mentioned here in mind as you move forwards.