Sentence:  If every the cultivation of <WSD>Rhubarb</WSD> in this kingdom becomes ſo extenſive as to ſuperſede the neceſſity of its importation; to the Society for the promotion of Arts, Manufactures, and Commerce, will the community be indebted for an advantage, the magnitude and importance of which cannot be too highly appreciated. From whatever cauſe, which it is unneceſſary here to inveſtigate, certain it is the conſumption of this valuable drug is increaſed, and continues to do ſo to a very great degree. 
Meaning of the word marked with <WSD> tags:  Any plant of the genus "Rheum", especially (noshow=1), having large leaves and long green or reddish acidic leafstalks that are edible, in particular when cooked (although the leaves are mildly poisonous).