4oS Yorkshire Naturalists' Union : Botanical Section. 



Marsh Ragwort. 

 DIP. Phovbia seneciella Meade. Adel Bog, Reformatoi-y side, 

 conspicuous by reason of the characteristic foam-like covering 

 of the larvae showing externally. 

 Cecidomyia spec. Houard, 5858, in the same place. 



YORKSHIRE NATURALISTS' UNION: 



BOTANICAL SECTION, ANNUAL MEETING, October 15, 1921. 



By the kind invitation of Prof. J. H. Priestley, this section met in the 

 Botanical department of the Leeds University. The afternoon was 

 devoted to a discussion on the effects of the abnormal weather, the gist 

 of which is incorporated in the Annual Report. The officials and members 

 of the various Committees for 1922 were recommended for election at the 

 Annual Meeting of the Union at Hull. 



Tea was taken next, the members being greatly indebted to Mrs. 

 Priestley and Mrs. Pearsall for their kindness in providing this stimulus 

 before the evening programme. 



Mr. W. H. Burrell submitted some notes on the Moss flora of Hard 

 and Soft waters. The general conclusions were that the majority of 

 aquatic bryophytes in Yorkshire waters were indifferent to the amount 

 of lime in solution ; some showed a slight preference for either hard or 

 soft water, and a few were strongly calciphilous (as Weisia verticiUata, 

 W. riipestris, Hypnum commutatmn, H. virescens) or calciphobous (as 

 Rhacomitriwn aciculare, Eitrhynchium myosuroides var. rivulare, Hyocom- 

 ium flagellare, Hypniini ochraceum) , and these were useful indicators of 

 the source of the water in which they flourished. 



The total hardness of the waters examined varied from 1° to over 15° 

 Clark. Streams of the gritstone moors showed 1° to 3° ; Mountain lime- 

 stone waters varied between 8° and 15°. The evidence suggested that 

 6° total hardness was the dividing line between hard and soft waters 

 from a bryological point of view, the mosses in certain streams showing 

 that amount of hardness being apparently controlled by the rock in the 

 stream bed rather than by the lime content of the water. 



Mr. J. W. H. Johnson dealt with a peculiarity in the Algal flora of 

 Gordale beck and Airehead, where at certain seasons Tetraspora gelatinosa 

 occurred in great quantity in certain isolated sections of the becks, the 

 cause for which still needed explanation. He also referred to the 

 abundance of a Bacterium — Microspora amoeba — in association with the 

 Alga, and pointed out that the purity of a water should be deterinincd 

 bj?^ the kinds of bacteria present rather than by their numbers. 



Mr. R. W. Butcher, in some notes on a study of Plankton in the 

 Wharfe at Harewood Bridge brought forward the interesting fact that 

 Tetraspora gelatinosa'wsiS present in his dredgings from the 'WTiarfe at a 

 period of the year immediately following the break up of the masses in 

 the Upper Aire at Gordale. He also exhibited specimens of Tillaea 

 fluitans recently discovered in the neighbourhood of Leeds. 



Dr. W. H. Pearsall submitted a note on the relationships of certain 

 mosses to soil acidity. Composite soil samples were taken representing 

 surface soil of a square metre, to a depth of 2 in. These were washed 

 with water, and the washings determined for acidity. In the quadrats 

 dealt with, the mosses showed varying degrees of tolerance : Mniinn 

 horniim and Catharinea undulata were complimentary, the latter being 

 plentiful on feebly acid soils, and the former replacing it on more strongly 

 acid soils. Hypnum cupressiforme covered the whole range of tests, 

 while Hypnum molluscum was restricted to the basic side of the neutral 

 line, and might be accepted as an indicator of soils containing carbonate 

 of lime. — Chris. A. Cheetham. 



Naturalist 



