7 
surviving plant has never been watered with Thames water and 
is quite healthy. 
The importance of providing an adequate supply of rain 
water for plants cultivated under glass at Kew was clearly 
demonstrated in the Temperate House. Plants which were 
supplied with rain water only have thriven throughout the whole 
of this extraordinary hot and dry year, whilst the same kinds of 
plants which were watered with Thames water are either dead 
or badly injured. 
The collection of Orchids comprises many species of such 
large genera as Coelogyne, Dendrobium, Cattleya, Masdevallia, 
Odontoglossum and Catasetum, many other smaller genera being 
represented by only a few or even a single example. Orchids 
generally require water that is pure, and they object to lime and 
salt. The collection has suffered severely from salt poisoning, 
and it is doubtful if many of the plants can recover. The nee 
for an increased storage of rain water for the T Range is abund- 
antly evident in the effects produced by using Thames water for 
the Orchids. Tropical plants in the same group of houses, most 
of which require abundance of moisture both at the roots and 
overhead, have suffered severely from damage by the salt water. 
The Nepenthes made very little growth and few pitchers com- 
pared with those of previous summers. Marantaceae, Musaceae 
and Scitamineae were greatly damaged by the salt, only very 
few of the large number of plants belonging to these three orders 
being sufficiently presentable to be left in the houses open to the 
public. The collection of Begonias has been utterly ruined, the 
bulk of the plants being either killed or very much injured. 
Many tropical Leguminosae were injured. The large plant of 
Amherstia in House No. 1 had all its leaves damaged, except 
those near the top, which the water from the syringe did not 
reach. Camoensia lost nearly all its leaves, as also did the 
-Heveas. All the species of Coffea and a large bush of Cacao were 
among the worst sufferers. 
Aroideae in House No. | have with few exceptions escaped 
injury, the Alocasias being the worst sufferers. The succulents 
in House No. 5 show no ill effects although they were regularly 
watered and hosed with Thames water. They include Cactaceaz, 
Euphorbiaceae, Liliaceae, Amaryllidaceae, Bromeliaceae, Solanaceae, 
Crassulaceae, Saxifragaceae, Geraniaceae, Compositae,Cucurbitaceae, 
Asclepiadaceae, Dioscoriaceae, etc. Tropical Ferns were fortunately 
watered with rain water only, there being a large and ample 
supply collected from the roofs of the houses and sto1ed in large 
tanks. The growth and general health of these plants have been 
unusually gcod this year. 
The following is a list of greenhouse plants which were injured 
by Thames water :— 
Abutilons, Leaves injured 
Achimenes ‘ 2? 3? 
Agapetes buxifolia ” » 
