scurf (n.) scurfy (adj.)

The white, powdery looking coating on some parts of a plant. It may be on the leaf, more commonly the underside, or the scape or bracts.

The leaf on the left from Aechmea fasciata has scurf or is scurfy . The one on the right from a Quesnelia does not.

It is due to the presence of scales, a mechanism for absorbing water from the air. It is so prominent on some Tillandsias that they appear not only silver, but sometimes almost furry!

It is a relative term. Some plants are more scurfy than others.