Table I. Basic biophysical parameters of stomatal guard cells in the open and closed state in V. faba and Arabidopsis.

References are as follows: Humble and Raschke (1971); Raschke et al. (1975); Blatt (1987b); Clint and Blatt (1989); Willmer et al. (1995); Willmer and Fricker (1996); Franks et al. (2001); Shope et al. (2003); Shope and Mott (2006); Meckel et al. (2007); Vialet-Chabrand et al. (2016); Xie et al. (2016). GC, Guard cells.

Parameter	Species
	V. faba		Arabidopsis
	Closed	Open	Closed	Open
Aperture (µm)	1.0–6.0	8.0–16.5	1–3	2–6
Pore area (µm2)	75–124	178–262	3–5	10–15
GC length (µm)	35–45	40–50	9–11	10–20
GC diameter (µm)	10–12	14–16	3–5	5–6
GC surface area (cm2 × 10−5)	1.2–1.6	1.6–3	0.2–0.3	0.3–0.5
GC volume (pL)	2.7–3.7	4.0–7.5	0.3–0.4	0.5–0.65
GC vacuole surface area (cm2 × 10−5)	0.96–1.2	1.3–1.6	0.15–0.23	0.25–0.43
GC vacuole volume (pL)	1.8–2.4	3.6–5.8	0.23–0.3	0.43–0.55
GC turgor (atm)	1–4	3.5–6	3–5	6–8
Plasma membrane voltage (mV)	−30 to −70	−100 to −180	−30 to −70	−100 to −180
Tonoplast membrane voltage (mV)	0 to −50	−10 to −40	0 to −50	−10 to −40