Data Set #1. Inside vs. Outside Leaves from a Dense Holly Tree (Bruce Grant and Itzick Vatnick - Widener University)

       Below is a data set for stomata for leaves taken from the interior vs. the outside (south side) of the foliage of a large holly tree on Widener's campus from the spring of 1999. The stomata were counted at 400x, and the students estimated the area of their field of view to be 0.152 mm^2.

inside leaves		outside leaves
slide stomata/field stomata/mm2 inside 1 41 270 inside 2 55 362 inside 3 40 263 inside 4 40 263 inside 5 42 276 inside 6 40 263 inside 7 38 250 inside 8 40 263 average 276.3 stan. dev. 35.3		slide stomata/field stomata/mm2 outside 1 43 283 outside 2 42 276 outside 3 47 309 outside 4 72 474 outside 5 59 388 outside 6 52 342 outside 7 53 349 outside 8 53 349 average 346.2 stan. dev. 63.6
t-test for unequal variances: t = 2.718 (d.f. = 11) for which t Critical one-tail = 1.796 and P(T<=t) one-tail = 0.010 The test shows that there is a 1 in a 100 chance of obtaining this large a t-value at random; therefore, the stomata density in the sun is significantly higher than in the shade.		click to enlarge...

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