44a 



PRIMARY ARRANGEMENT OF TISSUES, 



Taxineae, the genera Saxegothea, Dacrydiuin, Podocarpus (excepting the section Nageia), 

 and Tsuga with exception of T. Douglasii Carr. — there is one constant resin-passage 

 between the bundle and the epidermis of the lower surface of the leaf, either close to the 

 latter, often as a keel or ridge projecting outwards as in species of Juniperus, Thuja, and 

 Biota, or deeply embedded near to the bundle, as in Cunninghamia (Fig. 191). Besides 

 these there are in many species (e. g. Cryptomeria) accessory passages corresponding in 

 their arrangement to those which are constant in the Abietineae. One of these lies 

 (with the exception as above of Tsuga) at each lateral margin of the leaf close to the 

 upper surface; either this alone is present, e. g. always in Larix and Cedrus, or three 

 are also accessory ones in the hypoderma, the number and arrangement of which vary 



passage T^l^^SrSTbreL ?tV '""f"': "="«." ""°"«'' '"^ '=='' '=="'• " '"V^'- ' "PP" ^"*« i * '^^'^ 

 at its man;m to4rd"tS p„™chymn^^^^ '=?"" ^""==^"; '^ '"= ">i°-"aUed phloem , the white band 



ph,oe.. 7.ran3ve.el..eroJg"LT/^:„S"rato:"^cl\me Sron^'eler"'""' "'"""''^ "=^"= °' "" 



aiT^S^K ^''^ '•'"fu ^'"! '"'J'^'d"^': e. g. in the needles of Pinus sylvestris to such 

 an extent that 1-22 of them have been observed. 



triJ.nfS^ii^'"'^"-"^ Sciadopitys 4-10 passages lie under the epidermis, which are dis- 

 or double lelver^ symmetry over the margin and lower sides in relation to the simple 



traTer^sed hT.f f ^/^"'^™' °^"""^''^' ^"'^ Ginkgo, with several vascular bundles, are 

 the same plan! "" "^"^ P^^^^S^ ^ bundles ; they alternate with the latter in almost 



upwardnX^H rV^T ^T ™"«""°«^'y th>-°«gh the elongated leaves from the base 

 Edual iTt '"'"'' y^^ '"^t*'"^^ fr°«> the apex, which varies sometimes with the 

 sSrS beTor^h' .il^Pff • "Thus the median passage in species of Podocarpus, 

 stops far below the middle of the leaf. In the lamina of Ginkgo, in place of the 



