HO'RTUS BRITANNICUS. 



PART II. 



NATURAL ARRANGEMENT. 



EXPLANATORY INTRODUCTION. 



JL HE species under the different Classes, Orders, and Tribes, are enumerated with reference to their garden 

 culture, and the totals given under each of the principal Subdivisions, Orders, and Tribes. The space of 

 ground which the hardy plants of the different ordess would occupy is estimated with a view to the formation 

 of arboretums and herbaceous grounds, arranged according to the Natural System. In the latter estimation 

 the following rules have been adhered to : The rootless Cryptogamia, such as JV/usci, Hepatica?, &c., have not 

 been included. All climbers, whether ligneous or herbaceous, have been allowed a square of two feet on the 

 side. All other hardy plants, whether ligneous, herbaceous, or aquatic, under one foot in height, have been 

 allowed a square of one foot on the side ; all of one foot and under two feet, a square of two feet on the 

 side ; all of two feet and under six feet, a square of three feet on the side ; all of six feet and up to thirty 

 feet, a square of ten feet on the side ; all above thirty feet, a square of twenty feet on the side. Supposing it 

 intended to estimate, according to these rules, the space which the hardy herbaceous plants of any tribe or 

 order would occupy; then the first thing is to find the space allowed for each species or variety separately, by 

 multiplying the side of the square allowed to each species or variety by itself; the next thing is to add the 

 products of the multipliers of each separate species or variety together ; and the last process is to take the 

 square root of the total so obtained. This root gives the side of a square which would contain all the smaller 

 squares, and consequently the size of a square bed or compartment which would contain all the hardy her- 

 baceous plants of the tribe or order. Every gardener knows, or ought to know, how to modify this square to 

 a parallelogram, a triangle, or a circle, of the same capacity. 



The same process has of course been followed in estimating the size of the compartments requisite for each 

 of the orders and tribes of the hardy ligneous plants. The same also in ascertaining the sides of the squares 

 that will contain all the orders in a subclass ; all the subclasses in a subdivision ; all the subdivisions in a 

 class ; and all the classes in the two grand divisions of the system : or, in other words, of a square which will 

 contain all the plants which will endure the open air in Great Britain. 



In estimating the space requisite for every individual plant, the dimensions allowed may be taken indif- 

 ferently as the side of a square, or the diameter of a circle : since the extremities of the horizontal branches 

 or of the leaves of every plant may be said to form the circumference of a circle, of which its stem is the 

 centre ; and since in practice to place together any number of circular beds, is to place together the same 

 number of squares, the side of each of which is equal to the diameter of each of the circles. But it is 

 evident that a large circular bed of any given diameter will not contain so many smaller circles or squares, 

 as a large square whose side is equal to the diameter of the large circle ; the latter being contained within 

 the former ; and hence it is necessary, in adopting the circular form for any compartment which is intended 

 to contain more than one plant, always to add to the side of the square one eighth of its length, as the diameter 

 of an equivalent circle. Thus the side of a square which would contain the order Magnoli&ceas is sixty-two 

 feet ; but a circle to contain the same number of plants, with the same room to each, will require a diameter 

 of seventy feet, or eight feet more than the side of the square. One eighth part is not quite sufficient ; but 

 it is near enough for practice ; one seventh would be too much. 



In indicating the results of these calculations, to save room, a tree ({) is substituted for the words, Hardy 

 Ligneous Plants; an herb (}) for the words, Hardy Herbaceous Plants; and a water plant (=t), for Hardy 

 Water Plants. 



The utility of these calculations to gardeners, in designing arboretums or herbaceous grounds, will be very 

 considerable ; since it will enable them to proportion the size of every bed, group, or clump, to the hardy 

 plants which can be go % t to fill it. It will also enable those who wish to form small arboretums or herbaceous 

 grounds, to diminish tlie size of their groups in due proportion ; so as that their arrangement, however small, 

 may exhibit not only a specimen of the plants of every group, but by its size, relatively to the other groups, 

 convey an idea of the proportion of the plants fitted for temperate latitudes which that group contains. 



In general, it may be observed, that the best mode of laying out an herbaceous arrangement according to 

 the Natural System is by circular groups, on a plane, or on a regularly convex or concave surface, with a 

 circular boundary ; the space between the groups being covered with grass, gravel, or pavement. We should 

 prefer gravel, each group being edged by box ; because grass is unfavourable to walking on in moist weather, 

 and pavement, though cheapest in the end, is expensive at first. To arrange the groups systematically on 

 this surface, and at the same time to throw the numerous circles into agreeable figures, the following mode 

 may be adopted : Take three or four sheets of common letter paper; three or four sheets colored black on 

 both sides ; three or four red ; three or four green ; three or four yellow ; and three or four blue. Then fix 

 on a certain scale, say one foot to one eighth of an inch, being the common division of pocket rules, and with 

 a pair of compasses draw circles representing all the orders of Thalamiflbra? on the white paper ; of the next 

 subclass on the black paper ; and of the third on the red paper ; Monochlamydea? on the green paper ; Mono- 

 cotyledfcneae on the yellow paper; and the garden plants of Foliaceas on the blue paper. Next write the 

 name and number of the order or tribe on each circle. Cut out all the circles, keeping each color by itself, 

 and stick on the circles representing tribes on the large circle representing the order to which they belong. 

 Now paste several large sheets of paper together, so as to form a surface of the size and shape of the intended 

 arboretum or herbaceous ground, adopting the same scale as for the circles. Then take all the orders belonging 

 to one color, and arrange them in a figure, agreeable in point of effect, and correct with reference to the 

 affinities of the orders. The same as to the other colors. \ou have thus before you all the beds of the flower, 

 garden or herbaceous ground. After varying them in a great many ways, and having at last made a satisfactory 

 disposition, fix each circle in its place on the large paper with gum or paste, and the result is the working plan. 

 The same method of trial and correction will be found among the best for arranging a Systema Naturae 

 as a flower-garden on a lawn, or on any piece of ground of irregular shape in the pleasure-ground ; and it may 

 also be employed when the whole of the trees and shrubs in the park and pleasure-grounds of a residence are 

 to be planted in the order of nature. In the two latter cases, when the circles are all in their places, and 

 it is thought desirable to form irregular shapes, for the proper size and connection of such shapes the separate 

 circles are excellent indications. In laying out herbaceous arrangements, the circles of tribes belonging to 

 the same order, and sometimes of orders, may be joined together by bends, which in the execution on the 

 ground may be made six or eight inches wide. These bends, judiciously contrived, will aid in giving effect to 

 the general figure, as well as prove useful helps to the student in a scientific point of view. 



One of the most generally applicable methods of planting an arboretum is that of placing the trees and 

 shrubs along one or both sides of a winding shrubbery walk ; placing no tree or shrub nearer the walk, or 

 nearer another tree or shrub, than half its own height. A complete arboretum on this plan would extend along 

 at least two miles of walk ; a complete herbaceous ground, as will be seen by the estimate, would occupy an 

 acre and one third ; but all the orders and tribes both of hardy ligneous and herbaceous plants may be 



