The anatomy of bark. VI. Peppermints, boxes, ironbarks, and other eucalypts with cracked and furrowed barks

Abstract

The furrowed barks of peppermints, boxes, and ironbarks are due to cracks which extend through the rhytidome to the outermost phloem. In peppermints and boxes the cracks, which extend into the outer layers of the phloem, originate in the wedges of parenchyma that develop towards the periphery of the living phloem. In the peppermints the furrows are schizogenous in origin. In the boxes they are more often lysigenous, the direction of the crack being often determined by the lysigenous kino pockets that form in the outer phloem. In the ironbarks they are lysigenous, the cell breakdown occurring most often in the inner layers of the wide shytidome and only occasionally in the outer phloem. Much of the width of rhytidome observed in many boxes and ironbarks is due to at wide phellem; their hardness is due to kino which occurs either as cellular kino or as large pockets formed by the breaking down of tissues of the outer phloem.