Bretschneider, Hist. of Bot. Disc., I. p. 5 (Google Books ⧉, Amazon ⧉, Bookshop ⧉)

The Travels of Marco Polo

‘Polo is correct in giving Tangut as the native country of Rhubarb (Rheum palmatum), but no species of Rheum has hitherto been gathered by our botanists as far south as Kiang‐Su, indeed, not even in Shan‐tung.’ (Bretschneider, Hist. of Bot. Disc., I. p. 5.)