62 HERBACEOUS PLANTS 



but developing into shrubs and small trees of great worth in 

 warm countries. The tropical genus Hibiscus supplies dyes, 

 thickening for soups, flavouring for coffee, and rope. Gossy- 

 pium produces a fibre surrounding its seeds, known as cotton. 

 We import about a million tons of the raw material every year, 

 and another half a million tons of cotton-oil for making soap 

 and feeding cattle. 



The Hollyhock, Althaea rosea, is a conspicuous feature in 

 Indian gardens, and was formerly so in England ; but after 

 1873 the plants were attacked by the Hollyhock disease, 

 caused by a fungus, Puccinia, and the species ran a risk of 

 being exterminated. Sulphur-dusting is the best remedy. 



Closely related orders are 



Ord. 34. STERCULIACEAE. The Chocolate-tree, Theobroma cacao, 

 is growing in one of the stove-houses. 



Ord. 35. TILIACEAE. Forest trees. Three Limes on the bank of the 

 Cherwell : eight along the High Street. 



GERANIALES 



Ord. 36. LINEAE. Flax, Linum usitatissimum, will be found 

 in a small round bed near the middle of the plot, next to the 

 Mallows. Our imports of the seed of this useful plant amount 

 to close on 2,000,000 quarters per annum. After the linseed- 

 oil has been squeezed out, " oil-cake," the well-known cattle- 

 food, remains. 



The tribe Erythroxyleae are exotics. Erythroxylon coca in one of the 

 Green-houses. 



Ord. 38. MALPIGHIACEAE are one of the families which, by their rope- 

 like stems (lianes), contribute to the tangle of S. American forests. 

 Galphimia glauca in the Stove-house. 



Ord. 39. ZYGOPHYLLACEAE. Guaiacum is a West Indian genus. 



Ord. 40. GERANIACEAE, The Crane's-bills fill the south- 

 east bed of the plot. 



Tribe Oxalideae. The Wood-sorrel, Oxalis acetosella, is 

 stated to be the original of the Irish Shamrock, but owing to 

 the fact that it is not available as early as St. Patrick's Day, a 



