85^ 



REPOKT — 1903. 



9. On the Colonisation of a Dried River-hed. By Miss M. C. Stopes. 



The stream under consideration ran through meadows into the Thames, just 

 west of Northfleet, Kent. Its width was from 15 to 25 feet, locally widening to 

 40 or more, and there was an uninterrupted flow of 2 to 3 feet of clear water pro- 

 vided hy a perennial spring in the chalk. Aquatic animals and plants abounded 

 on the muddy bottom, and tangled masses of Potamogeton, Callitriche, Ranunculus 

 aquatilis, &c., floated to the surface. On the sides and banks were growths 

 of Typha, Phragmites, Sparganium, Myosotis, &c. 



The supply of water was tapped in the winter and early spring of 1900-1 by 

 the powerful pumps of a new waterworks, and by April 1901 all water had 

 ceased to flow. By July the mud was firm enough to walk on, and was broken 

 at short intervals by cracks 6 inches across and several feet deep. Last year's 

 plants had left very few traces either in or on the mud. The only true aquatics 

 still growing were R. aquatilis var. trichaphyllus, which retained its divided 

 leaves, one plant of which flowered, and Lemna minor living under an inch or two 

 of mud. Of semi-aquatics there were : — 



Few. 



Caltha palmtris. 

 Carex hirta. 



Uupatorinm cannabinum. 

 Junous articulatus. 

 „ obtusiflorus. 



CONSIDEEABLB NUMBEES. 



Scattered, 

 A liima plantago. 

 Carex riparia. 

 Digraphis arunditiacea. 

 Irii pseud- aoor lis. 

 Juncus communis. 

 Ranunculus sceleratus. 

 Rumex Jiydrolapathum. 

 Sparganium ramotum. 

 Scrophularia aquatioa. 

 Typha lati/oUa. 

 Veronica anagallis. 

 „ heccahunga. 



Total frequent — twenty, of which eight were locally dominant. 



Dominant locally. 

 Carex paludosa. 

 Epilobium hirsutum. 

 Olyceria aquatica. 

 Heloscladium nodiflorum. 

 Myosotis palustris. 

 Nasturtium officinale. 

 Phragmites communis. 

 Salix. 



Plants encroaching from land :- 



Few, 



Asparagus officinale 



(1 plant). 

 Convolvulus sepium (1), 

 Dipsacus sylvestris. 

 Hpilobium parvifiorum. 

 I'ield jjea (1). 

 Papaver rhrcax (2). 

 Phalaris caiiariensis (2). 

 Prunus communis, 

 Sonchus arvensis. 

 Trifoliiwi repens (2). 

 Vioia Cracca. 



Considerable Numbers. 



Scattered. 

 A nthoxanth urn odoratum. 

 Agrostis vulgaris. 

 Bromus sterilis. 

 Olyceria distans. 

 Holcvs lanatus. 

 Jliimulus Ivpiihis. 

 Polygonum hydropipier. 

 ,, periscaria. 



Rumex co)!glomcratux, 



„ ■ obtusifolius. 

 Solanvmi dulcamara. 



„ nigrum. 

 Tussilago farfara. 



Dominant locally. 

 Chenopodium Bonus 



Henricus. 

 Chenopodiuvi alba, 

 Equisetum pali/stre. 

 Polygonum InpathifoU n m , 

 Urtica dioica. 



Total frequent — eighteen, of which five are locally dominants 



There were, also, a little thalloid hepatic and moss which never reached 

 maturity, Funaria hygrometrica, one patch of Botrydium granulatum, and 

 Vaucheria down the cracks. Notable scarcity of Oompositse and Leguminosae, 

 as of Bryophytes and Algse. 



1902. — At first slow increase in dominance of land plants except grasses ; 

 absence of Alisma and Ranunculus aquQtilis, Lemna minor still alive uudtr 



