87 
25. COMMON PLEOSPORA. 
(Pleospora herb arum y Rab.) 
On languid loaves of Lisbon Lemon. Lancaster, Victoria. 
Orange leaves, Armadale, near Melbourne. Lemon twig. July, 
1899. Hawthorn, near Melbourne. (Fig. 53.) 
26 LEMON PLEOSPORA. 
{Pleospora limonum , Penz.) 
Scattered or loosely gregarious, minute, black, immersed, 
then erumpent pustules on brown-coloured portion of leaf 
surrounding tissue destroyed by P. omnivora, Perithecia de¬ 
pressed globose, dark-brown to golden-brown by transmitted 
light, coriaceous, of parenchymatous texture, fibrillose at base, 
up to 300/i. diain. with round to elliptical slightly papillate mouth 
(47/i. diam. or 65 x 40/z.). 
Asci oblong-clavate, sometimes somewhat cylindrical, rounded 
at apex and shortly stalked at base, 94-120 X 20-22/1. Para- 
physes hyaline, filiform, simple, tapering slightly at apex, equal 
in length or slightly longer than ascus, up to 10-septate, 2£-3/i. 
broad. Sporidia bright-greenish yellow, generally two-rowed, 
elongated oblong, five transverse septa, and three thicker than the 
others, not constricted at septa, except median, one also longi¬ 
tudinally divided, 24-30 X 11-13/i. 
On languid leaves of Lemon. August, 1899. Burnley, near 
Melbourne. 
This species has been found in Italy on the loaves of the Lomon, 
but rarely, and this may be owing to the fact that it appears only 
to occur at certain seasons of the year. 
I consider this to be the highest or Ascomycetal stage of 
Phoma omnivora from the mode of its occurrence. 
P . omnivora was found on the grey patch of the leaf where the 
substance is reduced by it to the epidermis, and that soon falls 
away. On the brown tissue immediately surrounding this, 
P. limonum occurred. On the 1st of May, some of the leaves of 
this Lemon tree were carefully examined, and only immature 
perithecia with asci were found, but on examining leaves from 
the same tree on the 4th of August, plenty of perithecia with 
mature asci were found. It would appear that after the Phoma 
omnivora has destroyed the tissue within a given area and weakened 
the leaf so that it soon falls, it produces its higher stage towards 
the winter (August), so that when the leaf falls to the ground, 
the spores may rest until a favorable opportunity for germination 
occurs. This may account for the occurrence of the fungus on 
