It positively influences tracheid production and explains up to 70% of the variability in tree-ring width.    From Wordnik.com.  [Direct climate effects on tree growth in the Arctic] Reference

Dendroclimatic analysis of tree-ring width, tracheid dimension and wood density variations in conifers along the regional temperature gradient (the Yenisey Meridian).    From Wordnik.com.  [Direct climate effects on tree growth in the Arctic] Reference

In ferns and conifers, the xylem only contains tracheid.    From Wordnik.com.  [CreationWiki - Recent changes [en]] Reference

Annual ring width, tracheid length and specific gravity in Pinus sylvestris trees grown on different sites.    From Wordnik.com.  [xml's Blinklist.com] Reference

Their walls are perforated (pierced with a hole or many holes) so that water can freely flow from one tracheid to the other.    From Wordnik.com.  [CreationWiki - Recent changes [en]] Reference