Fig. 2.

Phylogenetic relationships between non-commelinid monocots, commelinid monocots, eudicots excluding Caryophyllales (rosids and asterids) and Caryophyllales according to the Angiosperm Phylogeny Group IV (2016). The presence of Type I [cellulose microfibrils surrounded by xyloglucan (XyG) with large amounts of pectin; lignin containing H (p-hydroxyphenyl), G (guaiacyl) and S (syringyl) subunits] or Type II [cellulose microfibrils surrounded by glucuronoarabinoxylan (GAX) and some mixed linkage glucans (MLG), with little pectin; lignins containing H, G, S and ester-related p-coumaric acid (p-CA) sub-units] cell walls, dominant hemicelluloses, pectin abundance (++ = large amounts, + = small amounts), feruoylation (++ = large amounts, + = small amounts) and lignin sub-units are indicated. Data for cell wall composition are summarized from Harris and Trethewey (2010), Popper et al. (2011), Banasiak (2015) and Hatfield et al. (2017). Root cell wall cation exchange capacities (CECs, expressed as the range for n species) are taken from White and Broadley (2003), and gradients of the relationships between [Mg]_shoot and [Ca]_shoot are derived from the data shown in Fig. 1A and B.