Galls ... usually causing a pit on the under surface and a dome on the upper but the reverse may occur ... Sometimes a papilla is formed at the bottom of the pit [or] on the margins of leaves ... The dome may become pale yellow; the papilla may be darkened and the entire gall may become black, especially in the margins of the leaves ... Galls closed ... sorus lemon yellow, becoming orange ... black spot at bottom of dome indicates point of infection. Fungus lemon yellow becoming orange ... [on] Hydrocotyle umbellata