LINNEAN SOCIETY OF LONDON. 49 



the Colonies and various foreign countries, and in it is entangled 

 a variety of seeds. In the process of \vashing the wool the seeds 

 are swept into the river, and some of them, deposited on the 

 shingle or on the banks of the river, germinate and grow into 

 more or less hardy plants. In this way plants that ai-e natives 

 of Australia, IS'ew Zealand, Cape Colony, South America, and 

 other foreign countries are seen to be growing side by side with 

 plants of the British Flora. 



Erodium Botrys, Bert. No. 1 specimen. A South European 

 species. 



There are a great many European species of Erodium by the 

 river-banks and on mill waste-heaps. 



Medicago precox, DC. No. 2 specimen. 



This geuus, like the Erodium, is a very common one in the 

 Tweed district. Eight different species have been collected ; the 

 species now exhibited, however, has not hitherto been recorded. 



The history of this Medicago is interesting. Originally a South 

 European species, it has become widely spread in Argentina. 

 The Spaniards, in the sixteenth century, introduced into that 

 country some of their domesticated sheep which probably carried 

 some fruits of the Medicago with them. The seeds, finding there 

 a congenial soil, have flourished and now come back to Europe and 

 to the Tweedside in bales of wool. The fruits are also found iu 

 the wool of Australia and other colonies, and probably also have a 

 similar origin. 



The fruits, or burrs as they are locally called, are very detrimental 

 to the wool. This, however, is overcome to some extent by the 

 following process, which is now much practised in the manu- 

 facturing districts of this country and on the Continent. The 

 rind of the burrs is carbonised by a weak solutiou of sulphuric 

 acid, and then subjected to a dry heat of about ISO degrees. 

 Tlie burrs are then pulverised by heavy rollers and blown out by 

 strong fans. The seeds themselves are uninjured by this process 

 or even by being boiled in the process of dyeing. 



T'illcEa VaiUaniii, Willd. Specimen Xo. 3. Native of France 

 and Spain. 



Plentiful for two successive years. It has stalked flowers and 

 their parts are in fours, while in Tilloia muscosa the parts are in 

 threes, and the flower sessile. 



The genus Helipterum^ of which I have specimens of three 

 different species, Nos. 6, 7, 8, Ilelipterum corimhijlorum, Schlecht., 

 JleUpterum Jloribundum, DC, Hdipterum hgaloitpermum, F. von 

 Mueller, is perhaps the most interesting of these alien plants. 

 This geuus has hitherto been unrecorded for Great Jiritain, and 

 3'et has been found growixig as' far nortli as the banks of the 



LINN. SOC. PKOCEEDINGS. — SESSION 1910-11. e 



