152 ' Selectio7i of Plants for forming 



that the Natural Order Gramineae contanis 1071 species; but 

 of these species, being all grasses, every one will allow, that 

 any single one would give a tolerably correct idea of all the 

 rest. The same may be said of all the other orders, with 

 more or less obvious truth. In some very large orders the 

 truth may not be so obvious to a general observer ; but such 

 orders being divided into tribes, an individual of each tribe 

 will give to every one as clear an idea of that tribe, as a single 

 grass does of all the Graminese. 



As far as all the plants in the world have been described by 

 botanists, those which may be cultivated in gardens in the lati- 

 tude of Great I^ritain are included under 267 orders. (Lindl.) 

 All the plants known to botanists have not yet been introduced 

 into Britain ; but enough have been introduced to illustrate 

 215 orders, as enumerated in our Hortus Britmuiicus, from 

 p. 492. to 54-2. Hence, 215 plants would give a general idea 

 of about eight tenths of all the plants of the world, as far as 

 they are yet known and described. That division of plants 

 known to botanists as flowerless, or with concealed flowers, 

 with the exception of the ferns and one or two other orders, 

 are left out of view in this calculation, as unfit for cultivation. 



The garden plants of Britain, as enumerated in our tiortus 

 Britmuiicus, coming partly from warmer climates, are in part 

 cultivated in hot-houses, though chiefly in the open air. As 

 the latter is much the easier mode of cultivation, on account 

 of the first cost of the plants and their future management 

 being less expensive; the greater number of orders which 

 can be so illustrated the better. All plants are either ligne- 

 ous or herbaceous ; and some orders consist wholly of one 

 description, while other orders contain both. As hardy herb- 

 aceous plants occupy much less space than hardy ligneous 

 plants, the greater the number of orders that can be illustrated 

 by them, the less will be the space occupied. 



By the table which follows it will be seen that 114 orders 

 may be represented by hardy herbaceous plants, SQ by hardy 

 trees and shrubs, 33 by green-liouse plants, and 36 by hot-house 

 plants. By allowing an average of one square foot to each 

 herbaceous plant, and one square yard to each hardy tree or 

 shrub, the space occupied by them will be 438 square feet, or 

 one ninetieth of an acre. By allowing one square foot for each 

 of the green-house plants, a pit 9 ft. by 4 ft. sunk in dry soil, 

 or in wet soil built with hollow walls, will preserve them 

 through the winter, as well as any green-house ; making the 

 same allowance for hot- house plants, another pit 9 ft. by 4 ft. 

 heated by a flue or pipe of hot water, by a bed of stones 

 heated by steam in Mr. Hay's manner, by a bed of tan 



