Growth rate of the calcifuge plants Carex pilulifera, Deschampsia flexuosa, Holcus mollis, Luzula pilosa, Nardus stricta, and Veronica officinalis, transplanted into an Ordovician limestone soil of pH 8, increased by two to three times on addition of 5 mol m-3 of CaHPO4 compared to untreated conditions. For Galium saxatile, however, P treatment was lethal and growth was possible only in soil supplied with Fe(III) citrate, which had little or no effect on growth of the other six species. Phosphate treatment of the limestone soil greatly increased plant uptake of P, whereas P concentration of shoots from untreated soil was very low and probably highly deficient, compared to plants of field site origin. From this and two other recent studies it is now possible to conclude that the calcifuge habit of plants, at least under climatic conditions prevailing in northern Europe, is most often due to an inability of such plants to render the native phosphate of limestone soils available to plant uptake. Out of ten calcifuge species tested, only one exception to this rule was identified.Copyright 1994, 1999 Academic Press

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