Arrows

Arrows are pretty good in general, they're confident, you're making them grow pretty well, and the spaces between the folds are growing as well. Just two things; the first is that you can exaggerate a bit more how exponentially the spaces between folds and the width of the arrow grows as it gets closer to the viewer, it will help to communicate depth better. And the second one is to try not to make the arrows go outside the page. You can make use of dots to plan how much is going to occupy the arrows on the page to help you do this.

Leaves

Leaves are good too, though I would have liked to see more variety on the flows of the arrows themselves; more overlaps, more complex flows, etc. You also have some fraying on both ends on some of the contour cuves so take your time with them so this doesn't happen, ghost if necessary as well.

Lastly, about the added forms on the sides of the arrows, don't cut into the forms. If you can work additively, work additively.

I also think you might have been drawing some of these as if they were only 2d shapes, so try to think of each of them as a 3d form as well.

Branches

Branches are good as well, though a few issues:

-You do seem to be changing the degree of the ellipses on some places of some branches, but there are some where they don't change at all. Don't forget that even if a form is completely straight its ellipses of different sections will have different degrees.

-You also do apply the techinque of dividing the branches on different strokes, but sometimes you do your strokes too long, which makes them lose accuracy. A good rule of thumb is to make a stroke per ellipse each branch has, here is one of the branches were you did this

-Lastly, your transitions are good, but they sometimes are a bit rough. A way to make this better is to start your lines superimposing more on the previous line you've drawn, just like on the superimposed lines exercise. Here's an example.

Plants

On your plants in general you've done a great job! They look pretty solid to me. There are a few issues that I will point out, but like I said, good job overall!:

-First issues I find is basically what I pointed out on the branches and leaves sections, fraying on both ends on contour curves (potato plant or carnivorous plant), degrees of ellipses not changing (pitcher plant)

-Always approach everything in as much constructional steps as you can. For example, on this plant, you've done complex curves directly, while you could have started with simple curves, and then added complexity with other curves over them. Here's how I would have done it.

Another example on this same issue

-When adding forms, a single contour curve can help make them feel a lot more solid. If you don't do them, the objects can end up being flat. Like on this sunflower

Overall pretty good job! Keep in mind those things I said and go on with lesson 4, keep up the good work!