NECTRIA. 



189 



of Breslau, Berlin, Paris, Kew, Glasnevin (Dublin), and 

 Edinburgh. 



Nectria ipomoeae Hals.^ Stem-rot of egg-plant and sweet 

 potato. In America this attacks young growing plants, and 

 causes stem-rot. The Fusarium-stage developes as a white 

 mouldy coating on the withered stem, and is followed later 

 by flesh-coloured clusters of perithecia. 



Poly stigma. 



On the leaves of species of Prunus, one finds bright-coloured 

 spots, these are the stromata of this family, and in them 

 are embedded pycnidia containing hook- 

 shaped conidia. Perithecia embedded 

 in a similar manner are developed 

 after the fall of the leaves, they contain 

 asci with eight unicellular elliptical 

 spores, which are expelled on reaching 

 maturity in spring. 



Polystigma rubrum (Pers.) (Britain 

 and U.S. America). This appears as red 

 circular spots on the leaves of plum and 

 sloe. Micropycnidia are developed in 

 summer on the under-surface of the leaf 

 and give rise to curved conidia. The 

 perithecia begin their development in 

 summer, but only reach maturity in the 

 following spring, after the leaves have 

 fallen from the tree and lain on the 

 ground over winter. The asci are club- 

 shaped, long-stalked, and contain eight ^.^.^^^J^^ 

 spores, which are set free in succession SoTn ^^^hSTpSi. /.^"^ 

 from April to June. Germination ensues StteieS!'Tv.°?ubeuf?Fei.')^'' 

 on young leaves, and in six weeks 



pycnidia reappear. A variety, "Amygdali Desm.," is found on 

 the leaves of the almond {Amygdalus communis). 



Frank and Pisch found in connection with P. rvbrum^ 

 certain hyphae which they designate as trichogynes, while 

 they regard the small form of conidia as spermatia which 



^Description and illustrations in .A^. Jersey Agric. Exper. Station Report, 1891. 



Fig. S2. — Poly&tigma rubrum 



