Table 5.

The species means and standard errors (SE) for the needle traits. P. mugo: 40 needles from 4 trees were studied; P. sylvestris: 240 needles from 24 trees; H M × S: putative hybrids P. mugo × P. sylvestris (group B in Table 2): 110 needles from 11 trees; H S × M: hybrids P. sylvestris × P. mugo (group A; 80 needles from 8 trees).

Species	ROwABAX	Se	ROWADAX	Se	STOMR1	STOMR2	STOMEAN	Se	ROWINDEX	Se
P. mugo	8.4	0.27	6.6	0.20	47.5	48.8	48.2	0.5	1.31	0.04
P. sylvestris	8.5	0.15	8.2	0.14	54.6	55.1	54.8	0.4	1.06	0.02
H S × M (group A)	8.8	0.21	7.9	0.21	52.9	52.8	52.8	0.7	1.14	0.02
H M × S (group B)	8.8	0.18	7.6	0.22	52.4	52.7	52.6	0.5	1.21	0.03

ROWABAX and ROWADAX-number of stomata rows on abaxial (curvy) and adaxial (flat) needle surface; STOMR1 and STOMR2: number of stomata per 5 mm interval in row 1 and row 2; STOMEAN: mean of STOMR1 and STOMR2; ROWINDEX: stomata row index = ROWABAX/ROWADAX.