XVI International Botanical Congess

My collaboration with Margaret fuses anatomy with physiology, relating previously unrelated facts in ever-widening areas of explanation. The process is illustrated in a series of views of corn root anatomy, each view extending our understanding of the roles of tissues and the processes they operate. Water status of the root is determined by xylem maturation, and underlies soil adhesion, rhizosphere microflora and mucilage cementing. Elemental analysis of immature xylem initiated our cryo-microscopy of hydrated frozen specimens, leading to the discovery of water excretion from root surfaces and into intercellular spaces, of the absence of solutes in the mature vessels which might drive root pressure, and of gas in the sap of functioning vessels. The gas led us to the direct observation and quantification of embolisms, and of refilling embolized vessels, and into the vigorous controversy over plant water relations.