304 SUMMER CROPS. [Cuar. XVI. 
Several other summer crops are cultivated in the 
lowlands. Inthe southern provinces, for instance, 
we find large quantities of the Nelumbium speciosum 
grown for its roots, which are much esteemed ; the 
Trapa bicornis, the castor oil plant, Scirpus tuberosus, 
Convolvulus reptans, and several other vegetables, 
for which there is a great demand in all Chinese 
towns. The sugar cane also is extensively grown 
both in the provinces of Quantung and Fokien, and 
probably in other parts of the empire. 
In the district of Kiangsoo my attention was 
directed to a plant called Tein-ching, which is largely 
cultivated by the inhabitants for the sake of its 
blue dye. In the southern provinces a great deal 
of indigo (Indigofera) is grown and manufactured, 
in addition to a large quantity which is annually 
imported from Manilla and the Straits. In the 
north, however, the plant which we call indigo is 
never met with, owing, I suppose, to the coldness 
of the winters; but its place is supplied by the 
Tein-ching (Isatis indigotica), the leaves of which 
are prepared in the same manner as the common 
indigo. The colour of the liquid at first is a kind 
of greenish blue, but, after being well stirred up 
and exposed to the air, it becomes much darker. I 
suppose it is thickened afterwards by evaporation ; 
but this part of the process did not come under my 
observation. I am very much inclined to believe 
that this is the dye used to colour the green teas 
which are manufactured in the north of China for 
the English and American markets: this, however, 
is only conjecture. 
