The epidermis of petals also form a variation of trichomes called conical cells. These cells all develop from the pavement cells, which make up the majority of the plants surface cells. In short, cellular differentiation of the epidermal cells is controlled by two major factors: genetics and environmental conditions.
Azaleas and rhododendrons thrive in acidic soil. Azaleas and rhododendrons thrive in the acidic soil that is common under pine trees. Both plants are classified under the genus Rhododendron; the main difference is the smaller, funnel-shaped flowers on the azalea.ake soil samples from the area under the trees where you want to plant the azaleas or rhododendrons. Mix the samples in a bucket and test with a soil pH test kit.
How to Deal. Because sunburn is not something that will spread throughout the rhododendron, you have the option of just leaving the leaves alone and taking the steps necessary to protect the plant from the sun. New, hopefully healthy growth will eventually push out the sunburned leaves. Or, you can prune off the leaves. Pruning a rhododendron is not necessary, but it can clean up the appearance of the plant, control for size and rejuvenate old or diseased plants. Since rhododendrons are always pruned from the outside in, it won't hurt the plant to remove the stems containing sunburned leaves.