Tropicals & Tender Perennials: Does anyone know what causes this?, 1 by LeawoodGardener

LeawoodGardener wrote:
I'm a (relatively) new brugmansia gardener (I've had a couple varieties for the last four years) and this summer a very kind DGer sent me a couple starts and some unrooted cuttings from her brugs. The two starts are in pots on my patio and the cuttings are busy rooting on a window ledge in my office.

Recently the two starts have developed gnarled leaves - one of them is covered with the misformed leaves, the other only has the leaves on one side.

Can anyone tell me what's going on here?