A HISTORY OF BERKSHIRE 



THE LIVERWORTS (Hepatic^) 

 The recorded species include : 



Scapania nemorosa Madotheca platyphylla 



Jungermannia albicans Metzgeria furcata 



- crenulata var. seruginosa 



- sphaerocarpa Pellia epiphylla 



ventricosa Aneura pinguis 



pumila Marchantia polymorpha 



bicuspidata Plagiochila asplenioides 

 Lophocolea bidentata Frullania dilatata 

 Radula complanata 



but the damp woods of Aldermaston Soak, Padworth, Hermitage and 

 Finchhampstead are at present unexplored. 



CHARACE^ 



This curious group of aquatic plants, of which twenty-eight have 

 been recorded as British, and eleven of which have been found in 

 Berkshire, inhabit pools, streams and ponds, but are often of very 

 ephemeral duration, occurring sometimes in immense quantities for one 

 season and then disappearing for many years. They often occur in 

 newly cleared out ditches and pools, and it may be that the competitive 

 growth of leafy forms of phanerogams such as Callitriche exert a malign 

 influence by shutting out the sunlight, and that it is to this cause rather 

 than to the exhaustion of the food supply that their short-lived duration 

 is due. 



One of the rarest species, Nitella mucronata, was discovered in Britain 

 for the fourth time by me in 1892, and then it filled up a large ditch for 

 about 100 yards just on the border of our county at Godstow, and subse- 

 quently I found it on the Berkshire side of the Thames. It existed in 

 quantity till the following February, since which time I have been unable 

 to find it in the ditch where it was so abundant. 



On the basic strata of the north of the county the species Chara 

 vu/garis, C. contraria and C.fragilis, the latter chiefly as the var. Hedivigii, 

 occur, the latter often in great quantity in the Thames tributaries. 



Tolypella glomerata is very sporadic in its occurrence, and for one year 

 I noticed T. prolifera opposite the college barges at Oxford. On the 

 more silicious Bagshot sands Nitella Jiexilis and N. opaca, the latter com- 

 mon in Virginia Water, and the very handsome N. translucent are found, 

 Pools of stagnant water, as at Wytham, Buckland and Cothill, yield the 

 large species Chara hispida. 



FRESHWATER ALG^E 



Very little systematic work has been done at this group, but the 

 county affords very rich hunting grounds not only in the marshes and 

 ditches of the north but in the bogs and peaty moors of the south. In 

 the saline meadow at Marcham Vaucheria dichotoma var. submarina occurs. 



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