WHEELER, ELISABETH A.1* and PIETER BAAS2. 1North Carolina State University, Department of Wood and Paper Science, P.O. Box 8005, Raleigh, N.C. 27695-8005; 2Nationaal Herbarium Nederland, Universiteit Leiden Branch, P.O. Box 9514, 2300 RA Leiden, The Netherlands.. - Dicotyledonous woods: The fossil record.
Recent experimental studies on the hydraulic functioning of a range of
extant woody plants have demonstrated trade-offs between vessel
diameter, vessel density and total vessel length. Hydraulic
architecture can be classified into five extreme types: 1) long, wide
diameter vessels in high density (prevalent in modern lianas); 2)
long, wide diameter vessels in low density (prevalent in modern
lowland tropical rainforest trees); 3) short, narrow diameter vessels
in high density (prevalent in modern temperate diffuse-porous woods,
especially in desert shrubs); 4) a combination of long, wide earlywood
vessels and numerous, narrow and short latewood vessels (in modern
ring-porous woods of temperate and subtropical regions); 5) a
combination of long, relatively wide vessels and narrow, short vessels
mixed throughout the wood (in a number modern lianas and xeric woody
species). The first appearance of these 5 wood types in the fossil
record (1500+ records reviewed) and their incidence over time will be
briefly reviewed and related to environmental changes, as will the
wood anatomy of selected families, e.g., Fagaceae, Juglandaceae,
Lauraceae, Ulmaceae.
Key words: Juglandaceae, Lauraceae, paleobotany, secondary xylem, Ulmaceae, wood