388 PROTECTION AGAINST PLANTS. 



On sandfj soils we find chicflj' ling {Callium rulfiaris, Sal.) 

 and heather {Erica), broom {Cytisus scoparius, Link.), lyme- 

 grass {Elymus arenarius, L.), niaram-grass {Psamma araiaria, 

 Beauv.), sand-sedge {Carex arenaria, L.) ; Festuca r/lauca, 

 Schrad. ; Panicum f/lahrum, Gaud. ; etc. 



On clai/ soils: coltsfoot {ThssUckjo Farfara, L.), wound- 

 wort {StacJn/s pahistris, L.), marestail {Equisetum), cotton- 

 grass {Eriophorum), rushes {Junciis). 



On loam, on account of its favourable nature, very numerous 

 weeds abound, such as all good meadow-grasses, bindweed 

 {Convolvulus), Veronica, etc. 



Calcicolous weeds are VilHirnuni Lantana, L. (way faringtree ; 

 rock-rose {Helianthrmum vuhjarc, Gaertn.) ; Stachys germanica, 

 L. ; liuhus saxatilis, L. ; many PapHionacece, and of grasses, 

 Melica and Sesleria. 



On rich liunius soil: rasjiberr}^ {Ruhus Iclaeus, L.), balsam 

 {Impatiens Noli-me-tanriere, L,), hemp-nettle {Galeopsis Te- 

 trahit, L.), black night-shade {Solanum nigrum, L.), etc. 



On peats : we find mint {Mentha 'pulustris, L., etc.) ; bog 

 myrtle {Myrica Gale, L.) ; Vaccinium uUginos'um, L. ; Carex, 

 Eriophorum, Juncus, Scirpus, lousewort {Pedicularis), dock 

 {Iluniex), loosestrife {Lythruni Saliearia, L.), peat-moss 

 {Sphagnum, sp.), etc. 



On saline soils: sea milk- wort {Glaux niaritima,lj., Plantago 

 maritima, L.), samphire {Critlunum maritimum, L.), marsh- 

 samphire {Salicornia herhacea, L.), salt- wort {Salsola Kali, 

 L.), Armeria vulgaris, Willd. ; sea-lavender {Statice), sea-holly 

 {Eryngium maritimum, L.), maram-grass, etc. 



e. Mineral Substances in Ashes of Weeds. 



The mineral character of the soil on which plants will thrive 

 cannot be decided by the quantity of any substance such as 

 silica, calcium carbonate, or sodium chloride, which may be 

 found in their ashes. Different parts of the same plant 

 also contain different proportions of chemical substances. 

 Thus, there is mucli silica in the stem of grasses, and more 

 phosphates and potash in their seeds. 



The physical nature of the soil, i.e., its degree of moisture. 



