MIDDLESEX POTAMOGETONS 119 
Taphrina Carpinus Rostr. (Exoascus Carpini Rostr.), Frequent 
both over the chalk and lower greensand areas. 
PInE (Pinus sylvestris L.). Two examples observed in Woburn 
Foran so elevated as to be bcouseatile Near Baldock. Mr. 
Larcu (Larix europea DC.). One example; also seen in 
Woburn Woods. 
more crowded ind spreading than in the type. The normal 
foliage measures 13 to 14 mm. in length, the ‘Hisaned from 8 to 
10mm. The leaves show a number of dark spots, evidently the 
fruiting stage of a fungus. In transverse sections of. the leaves, 
prepared by Mr. W. H. Burrell, F.L.S., the mycelium threads are 
visible, some of which are knotted and twisted, apparently in their 
a. 
efforts to force a passage through the stomata. In reference to 
these Tubeuf ras)“ cum ade forms oeegecomt 
shoots in spruce.” Kerner says : ‘ Witches’ brooms also occu 
aig larches, and spruce s fires &e., although hitherto we navi sok 
e to ascertain definitely what parasitic fungi are the causes 
of these cases.’ Rare. Luton Hoo, Woodside. 
MIDDLESEX POTAMOGETONS. 
As unrecorded localities for this county are rms of interest, 
owing to the growth of London, &c., I give the following :— 
ees polygontfolius Pourr. Hounslow Heath. Herb. 
as ard | 
Ros betes Lackney M. Harsh. June, 1797, Herb. Salt 
at Sheti 
P. obtustfolins Mert. & Koch. Paddington. Sept. 9th, 1837, 
W. Wilson in Ca mbridge Herb. ! 
iz aoe ee, Link. Pond on Staines Moor, July 19th, 1879. 
H. Groves. This is a state of the plant with peduncles 1} in. 
e and leaves rather more apiculate than usual. In Fil. ee 
ex 296, “« P. compressus L. (P. mucronatus Schrad. Syme, E. B.) 
is localized “about Staines, abundantly,” on the authority of 
Hudson (Fl. Angl. ed. 2,76). Hudson knew nothing of acutifolius 
or zosterzfolius, but from his reference os R. Syn. (ed. 3), 149, 
ae mp doubt that the former was the plant intended. The 
Isle of Dogs locality in Fl. Midd. does, however refer to P. Friesit 
upr. (P. mucronatus auct.), as is shown the specimen from 
Goodiyer and Rozea (now in Herb. Mus. Brit} on which the record 
P. alpinus Balb. (P. rufescens Schrad.). The authors of the 
Flora of Middlesex say this ‘occurs in ditches by the Colne 
between Rickmansworth and Henefield Mill; a station which if not 
