EXPLANATION OF THE ILLUSTRATION 
Plate 4. Scanning electron micrographs (SEM) and a white light photomic- 
rograph (WLP) of cellular features from a contemporary specimen of Gor- 
donia lasianthus. Figures 2 through 4 are from wood silicified in the labora- 
tory and then deorganicized prior to maceration. 
Fig. |. Scalariform perforation plate. Untreated wood. SEM. X1000. 
Fig. 2. Siliceous lithomorph of a scalariform perforation plate. WLP (re- 
flected light). X570. 
Fig. 3. Lithomorph of a vessel element. The series of bars in the lower right 
corner are plugs of silica which deposited in the openings of a scalariform pit 
member between this vessel element and an adjoining cell. SEM. X5S00. 
Fig. 4. Lithomorph of ray parenchyma cells, showing impregnated pit 
cavities. SEM. X2000. 
40) 
