At'boriculture in relation to Geology. 293 



Italian poplar (P. acladesca), Lombardy poplar (P. dilatata), 

 the red-twigged osier (*Salix rubra), round- leaved sallow (Salix 

 caprea), the Huntingdon willow (^Salix alba ?), and the alder 

 (^'Inus glutinosa), all flourish with surprising success in a 

 trenched chalk soil, though it be almost destitute of any surface 

 covering of vegetable earth, and apparently barren. I regret 

 that I have not made more extensive experiments in the cul- 

 tivation of other species of aquatic trees on chalk soils ; but 

 those which I have mentioned ought to be considered as 

 affording sufficient encouragement to try the (Salix Russelh'aW 

 (Bedford willow), Populus macrophylla, or Ontario poplar, 

 and other valuable trees of similar habits. I feel, however, 

 called on to declare, that I am not aware of having observed 

 either of these trees spontaneously produced on the chalk, 

 except the ^alix caprea (sallow) and Populus alba (abele). 



The following is a catalogue of certain native British trees 

 and shrubs which I have observed to grow spontaneously and 

 vigorously on the chalk and its detritus: — 



AcQx campestre, common maple ; ^etula alba, common 

 birch; jBuxus sempervirens, tree box; Clematis Vitalba, tra- 

 veller's joy; Cornus sanguinea, common dogwood; Corylus 

 ^vellana, common hazel ; Cratse'gus Oxyacantha, whitethorn ; 

 jEuonymus europse'us, European spindle tree; Pagus sylvatica, 

 common beech ; Praxinus excelsior, common ash ; Juglans 

 regia, walnut; Jlmiperus communis, common juniper; Pigus- 

 trum vulgare, privet; Populus alba, abele tree; Populus 

 trfemula, aspen tree ; Prunus spinosa, blackthorn ; Pyrus 

 communis, wild pear tree ; Pyrus ikZalus, common crab tree; 

 Pyrus y^^ia, whitebeam tree ; Pyrus jSorbus, true service tree ; 

 Quercus Pobur, oak ; Phamnus catharUcus, buckthorn ; 

 Phamnus Frangula, berry-bearing alder, provincially black- 

 wood ; ^Salix caprea, round-leaved sallow ; iSambucus P'bulus, 

 dwarf elder [a herbaceous plant}; Sambucus nigra, common 

 elder ; Paxus baccata, common yew ; Pilia parvifolia, red- 

 twigged linden tree ; f/'lmus montana, wych hazel ; ?71mus 

 campestris, English elm ; Fiburnum O'pulus, Guelder rose, 

 provincially coppice alder ; Fiburnum Lantana, wayfaring 

 tree, provincially whitewood. 



There are certain of the upper beds of the chalk, of a fine 

 soft texture, the creta scriptoria, into which the roots of the 

 oak so penetrate, as to make that tree flourish in a singular 

 manner, attaining in those situations great height, and having 

 the bark of its young branches shining like silver, of beauty 

 not inferior to that which adorns the silver bark of the oak 

 woods on the schist of Devon ; but, generally speaking, the 

 oak on the chalk, though it spontaneously propagates itself, 



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