While I am going to ignore the confusion regarding construction-only/detail thing, there's actually a bigger issue in play here. Still not something that'll require a redo, but I'll touch upon it when I get into your plant constructions.

Starting with your arrows, you've got these flowing very nicely through space with a great sense of confidence and fluidity. Do however remember that as we look farther back, the gaps between our zigzagging sections will get narrower due to perspective, as shown here.

That sense of fluidity and confidence carries over very nicely into your leaves, where you're doing a great job of capturing not only how they sit in space but also how they flow through the space they occupy. One thing I want to draw your attention to however is that successive phases of construction - that is, when we introduce more complex edge detail and such - should not be approached with the kind of heavy additional line weight you've added here, nor should it be an attempt to redraw marks that have already been drawn. Keep the weight of your lines roughly the same, and focus only on drawing the parts that change as shown here on another student's work, as well as in this demo.

When it comes to line weight, that is added towards the end of a drawing, and it's important to keep it subtle. You're doing so quite heavily here (it actually looks like you're using a different pen, which you should not be doing). Line weight is essentially a whisper to the viewer's subconscious - subtle enough not to be visibly obvious to the eye, but something that the subconscious will pick up on to help clarify how certain forms overlap one another. When we get into the use of cast shadow in our constructions, that's an area where we can be much bolder, but cast shadows work differently - they do not cling to the silhouette of a form, but rather are cast upon a neighbouring surface, and therefore cannot be used quite in the same way as line weight.

Moving onto your branches, your work here is generally coming along well. You're doing a good job of getting your segments to flow smoothly into one another, achieving more seamless transitions, and maintaining the illusion of a single continuous form. Just don't forget to fully draw through your ellipses 2 times before lifting your pen, as discussed back in lesson 1.

Now, getting onto your plant constructions, the issue I was alluding to above is the fact that you approached most of your drawings with an underdrawing in green, followed by tracing back over those marks as needed to create your final drawing in black. This is not a process I want you to employ within this course, at all, as it contradicts many of the core principles of Drawabox.

Drawabox focuses on the idea that every single mark we put down defines a solid, three dimensional form, and that we are always working in 3D space. The way we end up approaching a clean-up pass either involves tracking back over our underdrawing - a process that itself focuses overmuch on how those marks exist as lines on a flat page, not edges in 3D space - or we end up cutting back across the silhouettes of the forms we'd already drawn and disregarding the fact that they exist there as solid, 3D forms, as explained here.

It is fundamentally important that we draw every mark towards the purpose of defining solid, 3D forms, and that we build upon those forms, reinforcing the fact that they exist in a 3D world by defining how they relate to their neighbours. Treating these things like they're just drawings gives us far too much freedom - the freedom to make lines that contradict the illusion we're attempting to present to the viewer. And so, remember that what you're doing here is not sketching. It is constructing, and we need to commit to every mark we draw, even where we might drift away from our reference image.

Aside from that key issue, your constructions are largely well done, and you even approach texture and detail fairly well (though of course, remember that the focus is not on creating a pretty picture, but rather in every drawing being an exercise in spatial reasoning - generally speaking the underdrawing thing leans pretty hard towards a focus on the end result).

I noticed that while earlier on, in one of your cactuses, you made pretty heavy use of hatching lines, whereas later on you were leaning more firmly into purposefully drawing clearly designed cast shadow shapes instead. That is a good improvement - in this course, stay away from hatching lines in general when it comes to your actual constructions. Hatching is usually employed when we try to shade our drawings, which as explained here is not something we're getting into in this course. While you leaned more into cast shadow shapes in most places, there were a couple spots where you fell back into basic rendering/shading, like in these venus flytraps.

Anyway, make sure that you do not rely on underdrawings in the future. Aside from that, keep up the good work. I'll go ahead and mark this lesson as complete.