Variation in Hypericum perforatum L. (St. John's wort) in New South Wales
M.H. CampbellA, C.E. MayB, I.A. SouthwellC, J.D. TomlinsonD and P.W. MichaelE
A NSW Agriculture, Forest Road, Orange, New South Wales 2800, Australia.
B Agricultural Research Institute, Wagga Wagga, New South Wales 2650, Australia.
C Agricultural Research Centre, Wollongbar, New South Wales 2477, Australia.
D CSIRO Bread Research Institute, North Ryde, New South Wales 2113, Australia.
E School of Crop Sciences, University of Sydney, New South Wales 2000, Australia.
Summary
Since 1929 it has been accepted that the only variety of the apomictic species, Hypericum perforatum L. (St. John's wort) in Australia is the narrow leaved var. angustifolium DC. To test this assumption specimens were collected in 1985-86 from various locations in New South Wales (NSW), grown in a common environment at Bathurst and examined for differences in morphology, cytology, chemical content, protein electrophoresis and germination characteristics. The specimens had a range of leaf sizes from what is accepted as broad (mean 12 x 24 mm) to what is accepted as narrow (mean 8 x 28 mm).
Differences between broad and narrow leaved plants could not be recognised using protein electrophoresis but broad leaved specimens were shorter, earlier flowering, had larger capsules, thicker stems, lower levels of hypericin and fewer glands in the leaves than narrow leaved specimens. There were no differences in chromosome number, all forms having 2n = 32. Because of the effects of environmental stresses on leaf size, the best time to distinguish between broad and narrow leaved forms in the field is in early spring when the new flowering stems are growing vigorously. It is concluded that all forms collected in NSW though they differ in leaf width, other morphological characters and chemical content are best considered as belonging to the same variable taxon, H. perforatum.
Plant Protection Quarterly (1997) 12 (2) 64-66.