epigeal dicot seedling anatomy radical-hypocotyl transition zone
 

Can anyone list some morphological charactersitics (visible to naked
eye or under low magnification) that might be used to discern the
radical-hypocotyl transition zone in seedlings of epigeal dicots? The
particular species I am interested in is Abutilon theophrasti. Some of
the observations will be made before root hairs develop so I am not
sure how to distinguish where the radical ends the hypocotyl begins.
It seems that there is some color changes and maybe the hypocotyl has
a smoother surface. I want to minimize the level of subjectivity in
the observations if possible.

Thanks!