What is the stomatal density on the upper and lower epidermis of hibiscus and colacasia leaves?

Why are my hibiscus leaves curling?

• I have 9 hibiscus plants that are hardy. Last year one of the plants leaves started curling. Now the one next to it and the one next to that one have started to curl. What is wrong?

• Answer:

  There are several different possibilities. The first and most likely is that your hibiscuses have a viral disease, which would be why it spread. I am not sure what can be done to cure that. A second possibility is that you hibiscuses have a fungal disease or some sort of insect infestation. You can combat those two possibilities through spraying pesticide and other chemicals. A final possibility is that they need more water. I know that citrus leaves curl when they are not given enough water. The same may be true of other plants This is the easiest to check. Try giving them a little more water and see if it helps. Some of this I know from experience, some I got from hibiscus world.