See:
Greenhouse Plants, Ornamental - Shoot Proliferation and Leafy Gall
Notes Plants commonly affected include Acanthus sp. (bear's breech), Argyranthemum sp., Aster sp., Geranium sp. (crane's-bill), Heuchera sp. (coral bells), Hosta sp., Iberis sp., Leucanthemum x superbum (Shasta daisy), lily, Monarda sp., Nemesia sp., Pelargonium spp., Petunia spp., Veronica sp., and Viola sp. A proliferation of partially expanded buds or shoots (a leafy gall) is the main symptom which often occur at the base of the plant. Diseased plants found in home landscapes can be left as they do not pose a significant threat to home gardens. Disease management depends on prevention but once an infected plant is introduced into a greenhouse, sanitation is extremely important.