Vascular architecture of the dendroid antipodean moss Dendroligotrichum dendroides (Brid. ex Hedw.) Broth. (Polytrichaceae)

Abstract

In vascular plants, when tracheary elements do not participate in mechanical support, they tend to follow Murray’s law. This means that the sum of the radii of the conduits to the third power (Σr³) is preserved across branching levels. Dendroligotrichum dendroides is a dendroid antipodean member of the Polytrichaceae growing in Chile and New Zealand, which reaches up to 60 cm in height and transports water internally. Its central hydrome of water-conducting cells has specific water conductances similar to vascular plants. We tested Murray’s law, and analysed other parameters of the vascular architecture and anatomy of D. dendroides from Chile. The water-conducting hydrome of D. dendroides follows Murray’s law, meaning that it is optimized for maximal water transport per unit of ‘vascular’ tissue biomass. There is also acropetal tapering and an increase in conduit number at ascending levels, similar to many vascular plants. Our results suggest that dendroid mosses like D. dendroides are subjected to similar biomechanical constrains in their ‘vascular’ design as tracheophytes and that similar selective pressures acted in the evolution of both vascular plants and bryophytes with conducting tissues.

Keywords:

• Dendroid mosses
• Dendroligotrichum dendroides
• Hydroids
• Murray’s law
• Polytrichaceae
• Vascular architecture

The present study was funded by project DIUC 209·415·012-1·0 and DIUC 212·418·003-1·0. Thanks to María José Parra for providing samples from Katalapi and for field assistance. Thanks to Jeffrey G. Duckett and one anonymous reviewer for their comments that greatly improved the manuscript.