The positions of the xylem and phloem are all different in the various parts of a dicotyledon. In this post, I'll share some ways that might make remembering/visualising them a bit easier.
The xylem in the root is....?
I guess it's not too difficult to "visualise" the position of the xylem in the root. We all know that roots absorb water for the plant... so the root should have a "big" vessel for water... right?
The one outside in the stem is the....?
For T.S. of a stem, because it's usually circular, you might want to think of a group of people sitting around a circular dining table as an analogy... would the food be placed further away from you or nearer to you? Yup, the food (phloem transports manufactured food) is nearer to you, that is, it's nearer the edge (the one outside). I've drawn an illustration of this.. maybe looking at it makes it easier to visualise..!
Eh... in a leaf, the one on top is the....?
To remember this, I think of rain (which is mainly water) and when it falls on a leaf, it touches the top surface of a leaf. Too far-fetched...? This is the only way I can think of to remember it easily... please drop me a message if you know of an easier way so I can share with others too!
I was kinda hesitant to share this initially. I'm worried that misconceptions might arise (with some of you thinking that water from rain is absorbed by the leaves directly into the xylem) so please keep in mind that water is absorbed by roots of the plant!
Hope these tips help!