Commentary Trait correlations in bryophytes: exploring an alternative world

Much has been written about trait correlations in vascular plants. In this issue of New Phytologist, Waite & Sack (pp. 156–172) have turned their attention to bryophytes, with some fascinating conclusions. During our schooldays we learn about ‘plants’ – the obvious plants around us, that is, vascular plants. Those of us who pursue the plant sciences further learn about the structure and physiology of these plants in ever-increasing detail, and it is natural for us to come to feel that the vascular-plant way is the only proper way for plants to do things! That view is compounded by an over-simplistic, linear view of evolution. However, the evolutionary ‘tree’ is not so much a tree as a thicket, many of whose branchings are hidden deep beneath the canopy of green leaves representing current living species. Every surviving shoot has had to prove its viability and make its own way up to the daylight of the present day. What is seen as ‘basal’ will depend on which shoot you start with at the top – a point repeatedly made by Dawkins (2004) – and may have little relevance to adaptation now, in the fourmillion-and-somethingth century since the origin of archegoniate land plants.