Mature spores have a dense exospore
coat, a pale endospore, and single rows of 8-11 polar tubule coils (Figure 2, panels B, C).
Perispore is microrugulate with rugulae homogenously distributed; it is adhered to exospore
in young spores but tends to detach; detaching usually begins at the laesure zone in mature spores.
Micromorphology of outer exospore
coatings in Selaginella megaspore.
4 urn in length and were characterized by an outer electron-dense exospore
and a thick electron-lucent endospore.
and in the supra-apertural chamber is
The outer exospore
is then covered by the perispore.
These changes are: #20, quadriseriate branching of axes/leaves absent [right arrow] throughout; #28, stele with radiating arms of xylem absent [right arrow] as rounded lobes; #41, radial axis/rachis trace round-elliptical [right arrow] lobed; #46, position of protoxylem in rachis/axis toward no face [right arrow] toward several faces; and #88, exospore
surface nearly smooth or plain [right arrow] obviously sculptured.