I am growing water spinach (Ipomoea aquatica) under grow lights indoors.
Most of them seem to have white 'hairs' growing on the under side of the leaves.
The cotyledons don't seem to be affected.
I don't think these are pest eggs since I am growing them inside and the hairs appear to be stable over many weeks.
The plants appear to be healthy as I've cut them above the nodes for a harvest and they are happily growing back with new side shoots.
The hairs seem to be difficult to wash off, it appears to be a growth from the plant itself.
There is no 'puff' of particulate (spores) released when the plants are moved or disturbed like what would normally happen with mould.
What are these growths? Are they safe to eat?
Update: 1 week later, and clearer pictures.
The side shoots are also now affected. There are a few dozen water spinach plants in this seedling tray and almost every plant is affected to some degree.
The plants still appear to be healthy as you can see they are growing more side shoots just below where I cut the main stem.
The hairs don't appear to be crystals of nutrient deposits. If they were crystals I'd expect them to feel hard, but instead they feel soft.