Urophlyctis pluriannulatus, an obligation parasite of Sanicula spp. . . . produces small crateriform galls on the petioles and blades of the host leaves . . . [The parasite] produce[s] marked enlargement of infected host cells . . . and cause[s] division of neighboring cells . . . [After] lysis of the surrounding walls . . . a large cavity is formed . . .