RUSTS. 
327 
its specific name from tlie fact that the pustules, which appear 
on both surfaces of the leaves, are often opposite to each 
other (Plate XII. fig. 5) . These pustules are generally seated on 
a discoloured spot (fig. 6 enlarged), and are surrounded by the 
remains of the ruptured epidermis. The spores are globose 
and brown (fig. 7). I have not met with any other Uredine on 
the sorrel leaves, though one having a similar appearance to 
the naked eye, is not uncommon on several species of dock. 
The fern rust ( Uredo filicum), which occurs on the under 
surface of the fronds of two or three species of ferns, I have 
never met with, and do not think that it can be considered 
common. It has been found in the west of England, on 
Gystopteris, and Sowerby collected it, probably not very far 
from London. 
One of the most common is the rust found on the leaves of 
the enchanter's nightshade ( Gircoea lutetiana), sometimes 
nearly covering the under surface with its tawny snuff- 
coloured spores. The plant on which it is found is rather 
local, but the rust ( Uredo Girccece ) seems to abound wherever 
the plant on which it is parasitic flourishes. Another fungus 
of a very similar external appearance may be collected, more 
rarely, from the leaves of the same plant, but in this the spores 
are two-celled, or divided by a transverse partition. This fact 
is mentioned to guard against disappointment, should the 
spores be found to differ from the characters of this section, 
and to show that the microscope is essential to the study of 
fungi. The spores of the true Uredo are globose and without 
any partition (Plate XII. figs. 3, 4) . 
I may also observe that a very interesting species may be 
found on several species of St. John's wort ( Hypericum ). 
Another occurs on the leaves of some of the wild garlics 
(Allium) ; one is not uncommon on some of the stitchworts ; 
another on saxifrages ; another on willow-herbs (Epilobium), 
and one on the leaves of the cowberry. All of these have 
yellowish spores. A species with brown spores occurs on sea 
lavender ( Statice ). Space to write on my own part, and 
patience to read on the part of others, induce me to dismiss 
all these species with the bare allusion to them and the plants 
on which they may be found. Some of them may occur in one 
locality and some in another, and enough has perhaps been 
said to enable any one to place any that he may find in the 
proper genus, if not with the scientific name. 
Prom the numerous instances I have met with of persons 
wholly disinterested in the subject, collecting, and making 
inquiries concerning the bright orange patches next to be 
referred to, I am led to conclude that most persons have, at 
least, seen them. These patches of orange-coloured powder 
