ECONOMIC WOODS OF THE UNITED STATES 17 



Taxus, and Tumioh, the tracheids are characterized by spiral 

 thickenings on the inner wall. 



TABLE I 



LENGTH OP TRACHEIDS IN CONIFEBOtFS WOODS 



Botanical Name 



Minimum 

 mm. 



Abies balsamea /6 ■ ./ . ',...'. . J .'tV- 



" concolor '^yT"' ■ f ■■■■/'■ ■' 



" grandis ^Ct-ix. i-A. ... ... > . . jr . . . . 



ChamsBcyparis lawsoniana ^tft:,. ^"^^r^ <!-'A4' 

 " thyoides .A^iJ^jT. . .€'. fC«A<' 



Larix occidentalis ^fi-X. C-.»>; J ■ ■ ■ ■ 



Libocednis decurrenSf-t^vt-jC.t ; .' y.C QXM-A^V. 

 Picea engelmanni. yt^.^.^.U i;..^.Y./m^K-.'< 



" rubens -<iC^. . . /i/'. 'i.'AJtX<: .... 



_" sitchensis,..-^.!?^ . . . . k-^t- .'.^. .^>r<. . 



/^W*«/«echinata.^:('. .(.'. .'l/. .'. . . .Ci 



' " eduHs A .'.,..'.. it«rv. ^ 



" lambertiana.'. .i :^'.^. ^'>:^. . C^j. 



" monticola. . .,:iL Li . . C-.1 -< 



" murrayana..c.>r/,f .< . .". .'. .'. .,. v 



" palustris. At:'.'-/,, .a. A y . . ..t 



" ponderosa. /.y.Ci.'/. .-. v'. '.,:. '.:'.!.:..'.... 



" resinosa "ll<h%ls-!A'r( Y. 



" strobus .4 1 ..''.!- .'.C ...... i.". 



" tseda .•W^4ri .■'. ;..(.'. C; r' .^ 



" virginiana. . . . ..y-'C. 1 t .<. i .- 



Pseudotsuga taxifolia. i^ei : .;. . .'; .*. .,> .'.i . . . . 

 Sequoia sempervirens . . /•• J, A . ; i^ .". e . ."^f. . . 



" washingtoniana . t.QA.if. ...„<<,': 



Taxodium distichmn. .U^^.Lcy. . .;.V.'. i;. y .'.-'. :'. 

 Thuya occidentalis. .Cf. •:'..._.}. -l-.f/. 



" plicata O.Ou/J:. 0.. . .'. : .-. . ,.;: .V.»- 



Tsuga canadensis. . P. . .'.t/v4. k; }..(.A^C. .V-. . . . 



" heterophylla . . .', . .'.«.' .(. :' :. v .V. 



2.00 

 2.75 

 2.90 

 2.55 



.45 



.75 



.00 



.05 



.50 



.30 



.40 



.50 



.75 



2.75 



1.80 



3.00 



2.50 



3.20 



3.20 



2.55 



1.75 



1.80 



4.05 



3.45 



3.65 



1.40 



3.15 



2.80 



1.75 



In certain conifers, particularly Pinus, specialized forms of 

 tracheids of a parenchymatous type are found associated with 

 resin ducts and cysts. They resemble wood-parenchyma cells in 

 form and fimction, but have bordered pits in their side and end 

 walls. Analogous to them are the ray tracheids foimd in several 

 genera of conifers. (See Rays.) 



The tracheids of broadleaf woods (Fig. 2, E) are subordinate 



