134 ECONOMIC WOODS OF THE UNITED STATES 



MuLTiPERFORATE : (Plural cirt-uUir or elliptical openings.) 



Few comparatively large openings (Ephedra; occasionally in 



Vaccinium uliginosum and Leitneria jloridana) . 

 Numerous small openings (Canella alba; Mennesia ferruginea) . 

 Pit-perforate: (Not readily distinguishable from pits.) (Oc- 

 casionally in Meisteria cernua, Lithospcrmuni Jruilicosum, 

 Cheirodendron sp., Rosa sp.) 

 Composite: (Mostly malformations occasionally met with.) 

 Simple-scalariform : (Quillaja, certain BignoniacejB, etc.) 

 Simple-reticulate: (Sorbus aucuparia, Sidonia vulgaris, Rosa 



sp., Cheirodendron gaudichaudii, etc.) 

 Scalarifoi-m-reticulate : (Didymopanax morototoni.) 



Simple perforations characterize a large majority of our native 

 woods. Where the plane of perforation is transverse oi- only 

 slightly inclined the simple type is ahnost invariably found. 

 Where the perforation is inchned it may be either simple or scaUui- 

 form. The opening may be circular, elliptical, or oblong- 

 elliptical. The elliptical form prevails where the plane of perfo.fa- 

 tion is o])lique. Usually the end walls are not completely removed 

 in the formation of a simple perforation and the border remaining 

 is called the annular ridge. This ridge may vary in width from 

 very narrow to fairly broad. 



There are a number of families in which all of the investigated 

 genera have exclusively simple perforations. Prominent among 

 these are the following: Aceraceae, Bignoniaceae, Ebenaceae, Jug- 

 landacese, Leguminosae, Moraccae, Salicaceae, and Tiliacese. There 

 are a number of others in which the simple type predominates but 

 where scalariform perforations are occasionally or rarely found in 

 the secondary wood or where, from the nature of the ])erforations 

 in the primary wood, they are to be expected. Important ex- 

 amples are the Betulacese, Fagaceae and Rosaceae. Both simple 

 and scalariform perforations may occur commonly side by side in 

 the secondary wood, as for example, in Fagus and Platanus. Oc- 

 casionally a segment is found in which the perforation at one end 

 is simple and at the other scalariform. Table VII includes nearly 

 all of the genera of native trees having vessel perforations exclu- 

 sively or predominately simple. The representatives of the 

 families marked with (*) (^xhibit some tendency toward the forma- 

 tion of the scalariform type. The more important genera are 

 shown in italics. 



