LEAF CHARACTER IN REVERTED BLACK CURRANTS

Abstract

ABSTRACT. A means is indicated whereby reverted leaves may be identified even in very slight cases or where the leaves have almost regained normality.This method depends (a) on counting the number of submain veins running from the midrib to points in the margin, and (b) on observation of the margin points, which also may if necessary be reduced to t numerical basis. That reverted leaves may be produced by artificial means, but that this reversion is of a temporary character. In each case examined the plant appeared to be under a special stimulus to growth. Cases in the field were examined in detail in three respects, namely (a) leaf vein number, (6) mite infected buds, and (c) leaf margin. Three classes could be distinguished: (o) normal healthy, (b) simple reverted, and (c) mite infected (reverted). These corresponded with three facton which appeared to be acting: (a) seasonal factor, (b) reversion factor, and (c) mite factor. Furthermore, since “oak leaf” is an advanced stag of reverted leaf and is always associated with mite, the chances an that reverted leaves when found without “oak leaf” owe their existence in some way or other to the mite factor either patently or latently.