516 FUNGI IMPERFECTI. 



"Eesembling JEelminthosporium in general habit and structure, 

 in fact only distinguished by the minutely warted conidia " 

 (Massee). 



Heterosporium echinulatum (Berk.).^ (Britain and U.S. 

 America.) The "fairy ring spot" of Carnations. This is a 

 serious enemy of cultivated carnations, and causes great damage. 

 It was first described by Berkeley in 1870 as a carnation pest- 

 The symptoms are light-coloured spots on which are concentric 

 rings of dark-coloured conidiophores. These arise from dark- 

 coloured portions of the mycelium inside the leaf and give off 

 conidia with three or more cells. The conidia are at first 

 terminal, but after one has been formed the conidiophore 

 branches laterally and produces another conidium, repeating this 

 process for a considerable time. The spots are produced on 

 leaves, leaf-stalks, and sepals, causing them to wither. In 

 consequence the flowers do not unfold and the plants are 

 rendered unsightly. 



Cultivation of the carnation in dry airy conditions is said 

 to. keep this disease in check. 



The following are British species occurring generally on 

 fading leaves : 



H. variabile Cooke. On spinach. 



H. omithogali Klotzsch. On Oi-nithoc/alum, Convallaria, and other 

 species of Liliaceae. 



H. typharum U. et M. On Typka angustifolia. 



H. laricis C. et M. On larch needles. 



H. asperatum Massee.^ Occurs as a parasite on Smilacina stellata. 



Napicladium. 



Conidia oblong, three or more celled, and produced singly 

 on the end of short conidiophores. 



" Somewhat resembling Helminfhosporium and Brachysporium^ 

 but distinguished by the less rigid fertile hyphae and the 

 large solitary conidia" (Massee). 



Napicladium (Helminthosporium) arundinaceum (Cord.). 

 (Britain.) This lives parasitic on the leaves of Phragmites 

 communis, and spreads rapidly from plant to plant. The leaves 



^ Worth. G. Smith, Oardener'n Chronicle, xxvi., 1886, p. 244. 



Atkinson, "Carnation Diseases" at American Carnation Society, 1893. 

 ^ Maasee, American Journal of Microscopy, February, 1893. 



