Phylogenetic and Ecological Signals in the Wood of Spathelioideae (Rutaceae)

Abstract

SUMMARYSubfamily Spathelioideae of Rutaceae constitutes a well-supported early branching clade of eight small woody genera that were formerly assigned to five different Sapindalean /Rutalean families. This study brings together detailed wood anatomical information on all eight genera (for four the wood anatomy is described for the first time in detail). Wood anatomy strongly supports the inclusion of all Spathelioid genera in Rutaceae and underpins the molecular phylogeny with a set of interesting apomorphies at different nodes of the cladogram. The wood anatomy of Cneorum tricoccon with its semi-ring porosity, dendritic vessel pattern, vascular tracheids and helical vessel wall thickenings stands out in Spathelioideae. This wood anatomical syndrome is hypothesized to be due to adaptive evolution for hydraulic safety and efficiency of this species in a typical Mediterranean climate, where similar syndromes have evolved in many unrelated clades of woody dicots. In at least six unrelated genera of Rutaceae outside Spathelioideae from Mediterranean or cool temperate and montane climates, the syndrome has also evolved in presumably parallel, adaptive evolution.

Chilean Pitavia more closely related to Oceania and Old World Rutaceae than to Neotropical groups: evidence from two cpDNA non-coding regions, with a new subfamilial classification of the family

“…The RTF clade corresponds to the bulk of Englerian Rutoideae, plus Toddalioideae and Flindersia . For discussion of characteristics see Waterman and Grundon (1983), Stace et al (1993), Groppo et al (2008), and Appelhans et al (2011, 2012b). …”

“…Another putative synapomorphy encountered commonly in the expanded Rutoideae (see Corner 1976 and Johri et al 1992) and in Cneoroideae (though absent in some, again due to a secondary loss, Appelhans et al 2011) is the presence of a tracheidal tegmen in the seeds. Additionally, Appelhans et al (2012b) discussed some wood anatomical characters shared by Spathelioideae (here Cneoroideae) and remaining Rutaceae, as the mainly 1-3-seriate rays in the secondary xylem. Figure 1 presents our chosen classification of the Rutaceae superimposed on that of Engler (1931), and Figure 2 summarizes some characteristics and putative synapomorphies of the major internal groups in the family.…”

Earliest fossil record of the genus Tetradium (Rutaceae) in Asia: implications for its evolution and palaeoecology

“…The presence of these two traits and the resulting hydraulic strategy, as a response to a seasonal climate, seems also to occur in the wood of Cneorm tricoccon L. (Spathelioideae, Rutaceae) (Appelhans et al . 2012). The wood of Tetradium nanningense provides new evidence for the appearance of these traits in different plant groups from this region in the late Oligocene (Huang et al .…”

The Piedra Chamana fossil woods (Eocene, Peru), II

“…In the InsideWood database, the combination of growth rings, minute intervessel pits, vessel ray pits similar to intervessel pits, non-septate fibers, diffuse to diffuse-in-aggregates parenchyma absent, axial parenchyma in strands of 2-4, elaborated paratracheal and widely banded parenchyma absent, rays not >1 mm, wood non-storied, and prismatic crystals (IAWA characters 1,24,30,66,91,92,136 with 65,76,77,80,83,85,93, occurs only in rutaceae (Balfourodendron, Fagaropsis, Harrisonia, Zanthoxylum). rutaceae generally have diffuseporous wood with growth rings marked by marginal parenchyma and/or differences in fiber wall thickness, vessels with simple perforations and alternate pitting, vessel-ray parenchyma pits similar to intervessel pits, medium-to very thick-walled non-septate fibers, and scanty paratracheal parenchyma (Klaassen 1999;Appelhans et al 2012). Very to moderately narrow vessels, intervessel pits minute to small, rays < 1 mm high, and absence of storying are also mentioned as typical (Metcalfe & Chalk 1950), as are vessels retaining a rounded shape in multiples (Crawley 2001).…”