The needles of 50 year old P. nigra J.F. Arnold subsp. laricio
Maire were collected during October 2009 (autumn season)
from the Souinet arboreta of the National Institute of
Researches on Rural Engineering, Water and Forests. Five
samples collected from more than 5 different trees were harvested and mixed for homogenization. The experimental
site is located in Ain Draham, in the north of Tunisia at an altitude
of 492 m, where humid climate prevails. The voucher
specimen of the plant (No. Pn.950) was prepared and deposited
at the herbarium division of the Institute.