Inequality in the Development of the Axillary Members in Glechoma hederacea L.

The vegetative plant of Glechoma hederacea has leaves and axillarybuds arranged in opposite and decussate pairs. The two individualsof any pair of axillary members (i.e. buds or runners) are oftenunequal in size although the leaves subtending the particularpair of axillary members seldom show any obvious inequality.A quantitative investigation of this inequality of the axillarymembers was made on clonal material. The lengths of the pairsof axillaries at 191 nodes on 25 horizontally growing runners(stems) were recorded. The degree of inequality of one memberof each pair of axillaries on a number of these runners wascalculated as its percentage difference from the mean lengthof the particular pair of axillary members. The positions ofthe axillaries on the runners were relatable to the four orthostichiespresent on the axillary buds from which the runners developed.At the even nodes (i.e. the second, fourth, &c. formed nodes)there was always a considerable degree of inequality betweenthe members of any particular pair of axillaries. The longermembers invariably occurred on the orthostichy of the runnerwhich in the undeveloped axillary bud lay adjacent to its subtendingleaf. At the odd nodes the inequality between the members ofany pair of axillaries was usually not so great and occasionallythe members were equal. Although the longer axillaries werenot confined to any particular orthostichy there was often atendency for more to occur on one of the two possible orthostichieson any given runner. Fifteen terminal runner buds were grown vertically in narrow-boreglass tubes for a varying number of plastochrons. At the 67nodes at which it was certain that the pairs of axillary memberswere initiated after the beginning of the experiment a similarpattern of inequality was found to that occurring in the horizontalrunners. It is thus concluded that gravity plays no part indetermining such inequality. A comparison was made between the degree of inequality of oneof the individuals of each axillary pair at a total of 18 nodeson four horizontal runners and the inequality (calculated fromlaminal areas) of the leaves subtending these axillaries. Thedegree of inequality of the subtending leaves was usually muchless than that of their respective axillaries and bore no constantrelationship to the latter.