Hila of full and empty longleaf pine seeds are distinguishable
Full and empty seeds of most longleaf pine trees (Pinus palustris Mill.) can be separated with a high degree of reliability by examining the hila. In this species the hilum, which marks the place where the seed was attached to the cone scale, is large enough to observe without a hand lens. lt is located where the wing is joined to the seed. ln all but a very few longleaf pine trees, seeds having a distinct hilum are full, while those with a faint scar are empty. Figure 1 shows the difference in prominence of the hilum on full and empty seeds from a single tree.