Arrows

Arrows look better this time, except top right and bottom left they grow as they get closer towards the viewer now, keep trying to make this more noticeable on the next ones.

One thing that can help to get smoother transitions is, just like in the branches exercise, overlap more your strokes as I show here. Keep in mind you can also add lineweight to the overlaps to clarify them with superimposed lines.

Leaves

On the leaves, you're going a bit wild with the flow, which is great, but in some leaves, like the left one feel like they would be impossible. Try to think more about how the leaf would fold naturally before drawing them. Another thing is the detail, keep in mind you should avoid cutting into your forms, draw additively every time you can.

Contours are fraying on both ends as well, so try to place your pen carefully at their start so they can only fray on maximum one end.

Branches

On branches you're mainly doing a main job too; the main problem is that the transition between strokes is a bit scratchy. A thing you can do to get the transitions smoother is to overlap your lines with the previous ones, just like in the superimposed lines exercise. Here's an example. Your branches get better on this by the end of your plant drawings, so good job!

Another thing is that even though you got some branches were the ellipses shift well, you do have some in which their ellipses don't change degrees throught the branch. Remember that just like with sausages, even if the branch is straight, the relationship between the viewer and the section of the branch will change, and thus the degree of the ellipse will change as well.

Plants

Now in your plants, I think you're doing mainly a good job. I'll try to cover the main issues I can catch so you can keep improving:

First thing I find is that you tend to have trouble alligning the ellipses to the minor axis of the branches. One thing that can help is starting by finding the major axis of the ellipses using their 90 degrees angle relationship with the minor axis, as I do here.

Second is that at times you could have gone a bit heavier on construction on some of the subjects. Always try to deconstruct everything as much as you can on the simples forms you can think of. Here's an example.

Third is pretty minor as it's only on the pot drawing, but in general, try to draw through all your forms. You can stop drawing through them if it gets extremely cluttered and doing so will make the drawing unreadable, but in general, try to always go for it.

And other than that, try to do one page per subject. There are some of them that gave you trouble because of their size, and doing so would have fixed that. Also, in the pages like in your potato plant, make sure you use the whole page. It can be hard to guess how much the drawing is going to occupy, and something that can help with that is to mark with dots the overall shape of the drawing. That way it'll be easier to make it fit in the whole page.

Other than that I think that your drawings are pretty solid by the end, and I can see improvement through the set, so I think you're prepared for lesson 4. Good luck with it, and keep it up!