19 



EPHEDRA [Fig. 30 A, B, Fig. 31 A, PI. II (facing p. 20)], WELWITSCHIA 

 (Fig. 30 C):- 



h^ 





Fig. 30. A, Ephedra antisyphilitica; uppermost detail-figure: section through 

 the exine along line x-y in the main figure ( x 2000); b, LO-patterns; the 

 detail-figure (■< 2000) between this figure and the main figure (x 1000) 

 shows a section through the exine at one of the short ends. B, E. equisetina; 

 cf. distal face (x 1000), surface and optical section; c, young grain with 

 sulcoid aperture. C, Welwitschia mirabilis; cf. lateral, transverse view ( x 1000), 

 exine stratification (x 2000), and cf. distal face (x 1000); uppermost detail- 

 figure: LO-analysis of part of the exine surface (to be read from left to right); 

 as the two central details show there is a very low and narrow ridge (bright 

 in the second, dark in the third detail from the left) at the bottom of the 

 valleys (sti])pled in the extreme left, white in the extreme right detail) 

 separating the hollow sexine ridges (white in the extreme left, stippled in 



the exti'eme right detail). 



