Genecologcal differentiation in Leptospermum flavescens Sm. in the Sydney region

Evidence is presented for the existence of two genecoiogically differentiated groups in Leptospermum flavescens in the Sydney region. A morphologicai study of 18 attributes of herbarium specimens indicates three groups of plants: one small-leaved, one large-leaved and one intermediate. Comparative cultivation under standard conditions and seed germination experiments indicate only two discrete groups, because the intermediate group behaves similarly to the large-leaved group. Correlation of population distribution with soil nutrient status suggests that organ size in the large-leaved group is phenotypically plastic in relation to low soil nutrients. This is confirmed by comparative cultivation under high and low nutrient regimes. Reciprocal transplanting of cuttings on a small scale suggests that the two groups are intolerant of each other's habitats.