A CASE OF EPHARMONY IN A NEW ZEALAND RUBUS

Abstract

Listen

Translate article

Under the term epharmony are here included all morphological changes that can reasonably be considered as due to a change of environment, and the plant so changed may be conveniently called an epharmone. Evidently epharmony is the concern of taxonomy as well as of general biology. Epharmone is an unambiguous name for those distinct modifications of form met with in nature but usually either neglected in floras or classed as varieties -a term so frequently used as a dumping-ground for forms of more than one biological status. In ecology too, epharmones of different life-f orms from the so-called normal - may be a better designa-tion-play quite different parts in the vegetation, and to apply to them merely the specific name is misleading in the extreme. The case here presented may serve, in part, to illustrate these remarks. In New Zealand, as elsewhere, the genus Rubus exhibits polymorphy to an astonishing degree. Yet the work of the last fifteen years has brought all local botanists to believe that the diversity of form in species generally is principally due to hybridism and epharmony. As the species now recognized number five only, and as their limits are already pretty well known, they give a convenient starting point for the task of bringing the forms into definite taxonomic groups. If this work be based on the recognition of the true-breeding units-the jordanon in my sense of that term-together with adequate study of epharmony and hybridism in the field, it is by no means so hopeless as might appear from the bewildering array of forms seen in herbaria, collected without reference to ecological evidence. Such work when completed will be based not on botanical opinion but on actual fact. Except for a creeping and rooting mat-plant, the New Zealand species, when fully developed and in their usual habitat, are high-climbing, scrambling lianes. Their main stems are rope-like, usually unbranched, covered with thick bark, and are many meters in length, with a diameter up to I5 cm. or even more. The leaf-stalks, and usually the midribs, are furnished abundantly with hooked prickles and serve as efficient climbing organs. Thus armed, the plants seize tenaciously anyone coming in contact with them, so that the vernacular name in New Zealand for Rubus is Lawyer. In the species under consideratioil, R. cissoides,l the leaves are for the