plowrightia

from The Century Dictionary.

• noun A genus of pyrenomycetous fungi having the perithecia embedded in black stromata and the spores two-celled and hyaline or light yellow. About 20 species have been described. P. morbosa is a parasite which attacks plum-and cherry-trees and forms more or less extensive warty excrescences on the branches, called black-knots. See black-knot, 2, and black-knot of the gooseberry.