Hi there!

Starting with your arrows, they're looking pretty good, though they are a bit wobbly, both the lines of the arrow itself, the hatching and the lineweight you've applied to the arrows. Don't forget that you should always prioritize confidence over accuracy. So when doing the lines, make sure you ghost them and that you focus on confidence, don't worry if the lines miss the mark or don't overlap perfectly in case of lineweight.

On branches take a look at this. And keep in mind that even if the branches are straight the ellipses degrees will have to change, you got some branches on your exercise in which the ellipses don't shift much. Other than these things they're looking pretty solid.

And on leaves this.

On plants generally you've done a good job as well. There are a few issues I want to comment on however, so you can keep improving:

First thing I want to comment on is drawing through forms and cutting into forms. Here on this plant, you could have worked additively instead and it would have been the same thing. As a rule of thumb if you can work additively work additively as it's easier.

About drawing through things, do it always that you can. For example on this same drawing you didn't do it on the pot. Don't forget to always do it.

Second is texture. On this plant you approached texture trying to scribble a bit. On drawabox you should always approach texture with purposeful marks, looking carefully at the reference before doing every single mark. Plan everything out and be patient. On this cactus another thing comes up, which is that you are outlining the forms when doing the texture of the plant. When doing drawabox textures you should also only draw cast shadows of the forms that cast them. You're not allowed to outline the forms unless they're breaking the silhouette of the subject. (As in the case of the fur thingy on the previous plant).

Third is connected with the cutting into forms thingy I explained before. This plant you did is an example in which working substractingly is actually the way to go. But just like with the additive method you should be in control of every line you do, which means not attempting complex curves in one go. Here's how I'd do it.

From here on, most of the issues on your drawings is stuff I've already commented on those. As a last thing, whenever you're approacing a form that has ellipses, such as a branch or a mushroom, draw always the minor axis first, so it helps you allign the ellipses properly around it.

Overall pretty good job like I said. The main issue I can see is the confidence with your lines. Make sure you focus on getting your confidence up on the next exercises. Congratulations on finishing lesson 3, and good luck on lesson 4!