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Polygonum mite is usually contrasted against the Hydropiper or 

 minus ; and as it is sometimes confused with one or the other of them 

 by good botanists, that course would seem to be necessary. Accord- 

 ing to my own view, it is much more closely allied to Persicaria than 

 to either of those two species ; and, indeed, I can separate it from 

 Persicaria by no other good mark besides the difference of inflores- 

 cence, which is slight enough in some examples. 



It may be that I am not sufiiciently familiar with P. laxum. If 

 understood, I take it to be simply a variety of lapathifolium. Taken 

 together, these two are readily distinguished from the rest by the hol- 

 low surfaces of their fruit. Persicaria and mite are recognized by 

 their larger flowers, which are opaquely milk-white when expanded, 

 though the perianth is usually coloured on the outside. Their fruit 

 distinguishes them from the two former, by its angularity or convexity, 

 from minus, by its greater size ; from Hydropiper, by its shining sur- 

 face. The flowers and fruit of minus are scarce half so large as those 

 of the other species. The drooping inflorescence, glandular perianths, 

 and opaque fruit amply distinguish P. Hydropiper, which is also fur- 

 ther distinguishable from mite by the narrower segments of the peri- 

 anth, and their more transparent or watery-white tint internally. The 

 real difficulty comes when Persicaria and mite have to be distinguished 

 fi'om each other, since we have only the difference of broad and slen- 

 der spikes for contrast here, and some examples of mite come rather 

 inconveniently near to Persicaria. 



In respect to some other characters which have been used for spe- 

 cific diagnosis, it may be said that they are too variable for reliance 

 apart from the fruit and inflorescence. Thus, the ochreae of mite are 

 sometimes almost glabrous, and those of Hydropiper are occasionally 

 strigose. The fringe of the same organ, formed by the excurrent 

 nerves, is absent in some of the upper ochreae of Hydropiper, and oc- 

 casionally present in some of the lower ochreae of lapathifolium. I 

 have seen both glabrous and hispid peduncles on the same plant of 

 Persicaria. The rounded or attenuated bases of the leaves are incon- 

 stant characters. And the stems of all these species (unless P. laxum 

 be an exception), vary from simple to much branched, from erect to 

 decumbent and rooting at the lower joints. On the whole, the fiuit 

 and inflorescence offer the best characters for specific diagnosis. 



I have not had the opportunity of seeing the figure and description 

 of P. mite, in the ' Supplement to English Botany.' Here I possess 

 only the small edition of that work, and I do not find P. mite among 



