Wood anatomy of Pinus longaeva (bristlecone pine) and the sustained length-on-age increase of its tracheids

Abstract

Length-on-age curves are presented for tracheids of three stems of bristlecone pine (Pinus longaeva). In the oldest stem tracheid length has steadily increased over the last 2200 years, and there are no signs of a levelling off. In the younger stems, which have the innermost rings dated 1484 and 1445 A.D., it appears that the 'juvenile' phase of steep increase in tracheid length of Pinus longaeva lasts several centuries. The methods of measuring tracheid length from narrow increment cores with a high percentage of damaged tracheids in macerations and in tangential sections using Ladell's method are compared. The wood anatomy of P. longaeva is described and found very similar to that of P. aristata. Both species differ in minor details from the related P. balfouriana. All three species share minute crystals in the epithelial and sheath cells of the resin ducts.