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Table 1 Correlation coefficients (r) of the first two axes of PCA and phylogenetic signals (K) for the functional traits of Dendrobium species in this study

From: Evolutionary correlation of water-related traits between different structures of Dendrobium plants

Functional traits Codes Units Species mean value PCA Phylogenetic signals
First major axis r Second major axis r K P
Leaf dry mass LDM mg 0.904** 0.085 1.163 0.044
Leaf water content LWC % − 0.857** 0.144 1.531 0.007
Leaf dry matter content LDMC % 0.863** −  0.209 1.720 0.009
Specific leaf area SLA cm2/g − 0.714* 0.640 1.415 0.019
Mesophyll thickness MT μm − 0.341 −  0.747* 0.931 0.138
Upper epidermal cell size UECS μm2 − 0.415 0.488 0.941 0.363
Stomatal density SD no./mm2 0.735* − 0.535 1.537 0.005
Stomatal volume SV μm3 0.204 0.895** 0.984 0.096
Stomatal area index SAI 10−2 no. 0.689 − 0.155 1.108 0.046
Vein density VD mm/mm2 0.301 0.071 0.862 0.366
Pseudobulb length PL cm − 0.032 0.967*** 1.022 0.041
Pseudobulb width PW mm 0.878** − 0.211 1.026 0.042
Pseudobulb internode length PIL 10−1 mm 0.513 0.789* 0.904 0.241
Flower dry mass FDM mg 0.474 0.767* 1.143 0.025
Flower water content FWC % − 0.748* − 0.457 0.888 0.204
Flower petal vein number FPVN no. 0.903** 0.037 0.921 0.393
Flower number FN no. 0.477 0.033 0.906 0.607
  1. K ≥ 1 refers to changes in traits that are strongly controlled by phylogeny
  2. K < 1 reflects traits that are less affected by phylogeny
  3. *p < 0.05
  4. **p < 0.01