The lower surface of needles of trees, particularly as influenced by the number and coloration of stomatal bands, can have a distinct influence on the appearance of trees. During February 1996 and January 1997, subjective ratings were made of the lower surfaces of needles of trees as follows: 1 = gray, 2 = moderately bluish, 3 = bluish. As had been used for upper surfaces of needles, a sample from a single tree that was judged to have moderately bluish (rating 2.0) lower foliage color was compared with each individual tree in the planting and a rating given based on the extent to which color was better or poorer. Detailed data are presented for the 1996 ratings.
Differences Between Locations
Trees of the North Carolina origins had the best ratings for color of the lower
surfaces of needles, averaging 3.31, bluish to very bluish. For the West Virginia
origins, trees from Blister Run were most highly rated (2.8, near the bluish),
while those for Blister Swamp, Stone Coal Run, Canaan Valley-State Park, and
Canaan Valley-Cortland Road had slightly-bluish to bluish ratings (2.4 to 2.6)
(Table 6).
Differences Between Seed Sources
Trees of SS-24 from North Carolina were top-rated (3.33) for color of the lower
surface of needles, followed closely (3.30) by those of SS-410, the other North
Carolina source. Of the West Virginia trees, SS-356 from Blister Run was top-rated
(2.98), and eight of 10 families from that area were among the third having
the highest ratings, while only one was among the lowest one-third. Four of
10 families from Blister Swamp were among the highest-rated group, with one
in the lowest-rated. Trees of families from the other three areas had not more
than one top-rated seed source and had four to six in the lowest one-third (Tables
3, 4, 6).
Details for 1997 evaluations of lower-surface needle color are not presented here. However, comparisons between evaluations showed that although ratings were slightly lower in 1997 (overall average of 2.53) than in 1996 (overall average of 2.62), ratings were highly correlated (r = 0.73, probability < 0.001).
Differences Within Seed Sources
Individual trees of North Carolina origins had, by far, the least variation
in lower-surface needle colors, with standard deviations of 9 and 11 percent
of seed source means for the two collections and ranges in colors of 2.5 to
3.5 for individual trees of both seed sources. For West Virginia trees, standard
deviations of individual seed sources ranged from 12 to 25 percent of seed-source
means (Table 6). For the top-rated West Virginia origin (SS-356), the range
in ratings of individual trees was from 2.0 to 3.5, while for the lowest-rated
family (SS-416), ratings ranged from 1.5 to 3.0.