GOOSEFOOT TRIBE. BUCK-WHEAT TRIBE. 489 



under the name of mangel wurzel^ or root of scarcity, to furnish 

 winter food for cattle; it is often a very profitable crop, the 

 roots growing to the weight of 20, 30, or even 601bs. ; and it 

 does not exhaust the soil. Another species or variety of Beet 

 is extensively cultivated in France, on account of the sugar 

 which it yields ; this product is not so good as that made from 

 the cane, nor can it be raised so cheaply ; nevertheless the nation 

 is obliged to employ it, on account of the heavy duty which is 

 placed upon the sugar of the West Indies, Brazil, &c. Another 

 plant, which was at one time of much importance, is the Salsola 

 soda, which, when grown near the sea-shore, contains a large 

 quantity of the alkali Soda ; and this was obtained from it by 

 burning. Soda is now more abundantly procured, however, by 

 other processes. Another British genus, the Salicornia or Glass- 

 wort, was of similar utility ; this is remarkable for having but 

 a single stamen. The genus Atriplex, or Orache, deserves men- 

 tion on account of its being polygamous^ that is, bearing com- 

 plete, as well as incomplete flowers on the same plant. The 

 complete and stamineous flowers have a five- parted calyx ; whilst 

 the calyx of the pistilline flowers is formed of two valves only. 



66(J. The next order to be mentioned is that of POLYGONS, 

 or the Buck-wheat tribe, which, like the last, contains many of 

 the most common weeds that overrun waste places in every lati- 

 tude, together with sevepal important plants. The characters of 

 this order are easily recognised. The perianth is composed of 

 from three to six pieces, adherent at the base, and folded over each 

 other, sometimes to such a degree, as to give the appearance of 

 a double whorl. The stamens are usually few in number, and 

 are inserted in the bottom of the perianth. The ovarium is 

 superior, with a single erect ovule in its cavity ; and has more 

 than one style or stigma. In these respects, the Polygoneae do 

 not present any marked difference from the Chenopodeae; but 

 they may be distinguished by this important character, that, 

 whilst the latter are destitute of stipules, the former have them 

 very large, and cohering round the stem, so as to inclose the 

 leaf-buds, before they expand, in the manner of a boot ; this is 

 well seen in the common garden Rhubarb. The seed usually 



