Honestly, the concerns you listed made me worried that this would be a difficult critique... but looking at your actual work, I think you're just a little prone to being afraid that you're doing the wrong thing. In all honestly, your work throughout this lesson is actually very well done.

I'll answer both your questions, of course, though I'll leave the first for when I get to your branches. When it comes to distinguishing construction from detail, it's a little more useful to refer to the latter as "texture" instead. Construction is all the information we convey to the viewer to tell them what it'd be like to manipulate the object in their hands, and we approach it using explicit/constructional drawing techniques. We outline our forms, and clearly establish their relationships with other neighbouring forms. Texture is all the information we convey to the viewer that tells them what it'd be like to run their fingers over the object's various surfaces. These are the things we convey using implicit, textural drawing techniques, focusing on only the shadows those forms cast on their surroundings (aside from the spots where those textural forms push past the silhouette of the larger object to which they adhere). We do not employ any outlines for those forms, but rather imply the presence of those textural forms through the shadows they cast on their surrounding surfaces.

All of these address forms, and it is ultimately up to you where you draw the line between constructed forms and textural forms - but there are rules of thumb which you can apply. For example, if a form exists stuck to the surface of another form, especially if there are a lot of those smaller forms all clinging to that surface, then that starts to smell of texture. If however a form is floating freely in space, or isn't really adhering to any surface at all, then it's hard to approach it any way other than constructional. There are grey areas where you can choose for yourself, but depending on the circumstance, you'll find one approach applies better than the other depending on the case.

Now, I certainly did want you to draw each and every constructed form in its entirety - every single leaf, regardless of how unreadable you feel the result may appear. In fact to me, that first plant isn't particularly confusing to look at, specifically because my eyes have been trained over the last many years to insect drawings of this sort. Because, as you probably well know, these are all exercises, designed to help you develop your understanding of 3D space. As you continue to do them, you'll get better at being able to tell what's going on. Surely they're not for the average viewer who's just here for a pretty picture - they serve a deeper purpose tied to what they teach you through their very process.

Now while what you've drawn may confuse you, you have shown a fair capacity to understand it well enough to produce it, not to get overly confused by it, and to leverage line weight to help clarify some of those overlaps. Were it truly a disorganized mess, we'd address that - but since it isn't, I'm pleased with your results.

Now I'm getting ahead of myself, as there are other exercises to get into first.

Your arrows are looking solid. They flow smoothly and confidently, and you're showing a clear awareness of how foreshortening ought to apply to both their positive and negative spaces. You carry that strong sense of flow and fluidity over into the arrows, where you've first and foremost captured how those leaves not only sit in 3D space, but how they move through the space they occupy. You clearly focused on establishing this first, and then went into greater complexity by building out the more complex edge detail, and then digging into the textural aspects all in their due time. As a result your leaves still feel solid and believable, but convey a ton of information to the viewer. Very well done.

You mentioned you weren't happy with your ability to draw ellipses at a similar enough size throughout, and while objectively it's true that they're not precisely all the same size, I think you're being way too hard on yourself. What I'm seeing are branches that still appear solid, whose ellipses are close enough in size, and whose segments flow seamlessly and smoothly from one to the next without overwhelming breaks in their flow. There are little visible tails here and there, and what would help is to always remember to extend them fully halfway to the next ellipse (as shown here), as you sometimes only extend them a little past the previous one. Still, your work here is really well done and as a result those branches feel like solid 3D forms.

Now, getting back into the plant constructions, as I mentioned you've done a good job overall. There are just a couple things I want to touch upon that I haven't yet:

• This cactus is really the only weak drawing of the bunch, which usually means it's not worth talking about due to its status as a statistical outlier. All the same, there are reasons it didn't come out well. Firstly, you didn't draw through the forms in their entirety, establishing them more as 2D shapes rather than interpenetrating 3D forms. Relatedly, leaning so heavily on individual contour lines that sit on the individual forms, rather than taking advantage of the opportunity to really push how those forms connect to one another (think more intersectional contour lines) resulted you using twice as many lines for half the effect. This one isn't your fault - it's simply not something we've gotten into as much yet, but it's worth mentioning here. The contour lines we use in the form intersections exercise define the relationship between two forms, and in doing so, they become far more effective than those that sit on a single form from the contour lines exercise. Often times, if you're able to leverage them well, you can make the latter kind of contour line unnecessary. Another reason this drawing didn't come out too well was that each individual mass was actually more complex - not just a simple ball, but a ball with a tapering end, and that complexity further undermined its solidity. Anyway, again - every other drawing you did was overall successful, so this one was an experiment gone wrong. That's all.

• For this one you again didn't draw through your leaves, but here the result wasn't quite as harmful to the overall drawing. I really cannot stress enough however how important it is that you draw through your forms in these exercises. Another issue I noticed was that your cast shadows aren't consistent - you've got the same form casting a shadow both above and below it on the page. Assuming a single light source (which without any other obvious signs is what the viewer will assume), the shadows should be biased towards one side. Always keep the location of your light source in mind.

• For these tomatoes, you appear to have drawn them quite hesitantly - make sure you draw through your ellipses to keep them nice and smooth. The hesitation in your lines undermine the solidity of that form. Even if the form you're after isn't entirely round (one of them appears to be intentionally a bit flatter on one side, though I'm not sure if that's from the reference), the ball form is a good starting point. Whether or not that flattened section is something you want to pursue as part of this drawing is something you can decide once that mass is present in the world, and believably so. Remember that our job here is not to reproduce a reference image - it is to communicate what the image itself conveys. Should we decide the uneven shape of the tomato is important, then we can take steps to build that up in the form (though that's a bit more advanced, something we'll tackle in the next few lessons in how we can build more forms on top of the base structure, wrapping them around). That said, it is not a requirement - we may decide that this aspect of the reference is unimportant, or even contrary to what we wish our focus to be. It is our decision what we wish to convey.

So! With that, I'll go ahead and mark this lesson as complete. Keep up the good work, and remember to draw through your forms in every instance.