Table 3.

Ordinary least squares (OLS) regression model parameters with lower and upper confidence limits (CL) and tests of common slope (ANCOVA) among leaves. Relationships for each leaf, species, and across multiple species of water mass per area (WMA) with terahertz transmission (ln PFR) were tested and used to predict relative water content and leaf water potential. P‐values for individual leaves represent the fit of the linear model, and for common slopes, represent a test for the significance of variation in slope among individual leaves or among species

Species	Leaf	Slope (Lower CL, Upper CL)	Intercept (Lower CL, Upper CL)	R 2	p value
Arabidopsis thaliana	1	−343 (−656, −30.2)	−3.24 (−210, 203)	.88	.0421
	2	−332 (−566, −97.0)	−72.8 (−320, 174)	.83	.0205
	3	−223 (−263, −182)	19.7 (−8.57, 48.0)	.99	.0004
	4	−1002 (−1727, −277)	−521 (−1095, 49.9)	.95	.0277
	5	−312 (−582, −42.7)	−63.0 (−333, 207)	.93	.038
A. thaliana common slope					.0370
Hedera canariensis	1	−322 (−377, −268)	−211 (−286, −135)	.99	<.0001
	2	−300 (−496, −103)	−165 (−417, 87.8)	.82	.0130
	3	−179 (−193, −164)	−33.3 (−51.9, −14.6)	.99	<.0001
	4	−281 (−357, −205)	−114 (−203, −24.4)	.96	.001
	5	−340 (−664, −16.4)	−357 (−895, 181)	.59	.043
	6	−353 (−575, −132)	−3.45 (−721, 30.2)	.77	.009
H. canariensis common slope					.001
Platanus racemosa	1	−347 (−523, −172)	−139 (−311, 33.3)	.85	.005
	2	−128 (−164, −91.1)	13.0 (−33.9, 59.8)	.95	<.001
	3	−151 (−272, −30.6)	−9.70 (−149, 130)	.69	.025
	4	−97.1 (−110, −84.5)	16.9 (4.90, 29.0)	.98	<.0001
	5	−147 (−173, −122)	−27.3 (−49.5, 50.0)	.97	<.0001
	6	−89.5 (−107, −72.3)	39.4 (28.6, 50.2)	.96	<.0001
P. racemosa common slope					.003
Arabidopsis thaliana		−133 (−172, −96.5)	82.0 (−28.5, 44.9)	.55	1.28 × 10–5
Hedera canariensis		−91.7 (−135, −48.6)	90.3 (28.0, 153)	.34	.0001
Platanus racemosa		−245 (−339, −151)	90.0 (−71.7, 89.7)	.57	9.17 × 10–9
All species		−125	48.0	.37	2.25 × 10–12
All‐species common slope					.022