615 



Notes on Polygonum maritimum and P. Rati, as grown together in 

 Jlower-pots inland. By Hewett C. Watson, Esq. 



In the current volume of the ' Phy tologist ' (Phytol. ii. 45 and 333), 

 are some brief notes on the approximation of P. maritimum towards 

 P. Roberti (British Flora) or P. Raii (Bab. Man.), when cultivated 

 inland in a garden. Last autumn I was kindly supplied with seeds 

 of the British P. Raii, by the good offices of the Rev. W. S. Hore. 

 Some of these were sown in flower-pots, at different dates in ihe 

 spring of the present year ; as also, seeds of the garden-descended 

 P. maritimum (of Azoric origin, in 1842) in other pots at the same 

 time. 



The cotyledons of the two were scarce distinguishable from each 

 other, in their stage of vegetation ; but after the appearance of two or 

 three of the earliest true leaves, the plants were so visibly different 

 that had they all been pulled up by the roots and mixed together, it 

 would have been perfectly easy to separate them into their two origi- 

 nal species or varieties. This does not prove them to be permanent- 

 ly distinct, as species, although it may increase the probability of 

 such being the fact ; as it so far shows their peculiarities to be trans- 

 mitted, without inter-commingling, for one generation, when external 

 conditions are made equal. 



In its early state, the Polygonum Raii might more likely have been 

 mistaken for the ordinary corn-field form of Polygonum aviculare, 

 than for Polygonum maritimum ; but in its more advanced stage of 

 flower and fruit, the resemblance became much closer to the P. mari- 

 timum than to the P. aviculare. 



The young plants of Polygonum Raii grew quite erect until two or 

 three inches high, when the stems suddenly bent at one of their lower 

 joints, almost at a right angle, so as to give a horizontal direction to 

 their growth. At the time of writing this notice (August 20), their 

 stems and branches are eight to twelve inches long, still keeping to 

 their horizontal mode of growth, and very slightly bending upwards 

 at the growing extremities. They neither hang down over the sides 

 of the flower-pots, as would any creeping or softer-stemmed plant, 

 nor do they ascend much above the rims of the pots, except that, 

 when v/et by rain or dew, they incline below the horizontal line, ap- 

 pai'ently through increase of weight upon the wiry stems. Compara- 

 tively with those of P. maritimum, the ochreae are thinner and much 

 less nerved ; and although pretty long at first, they tear and wear 

 away more rapidly. The leaves are longer in proportion to breadth. 



