The marginal processes were flat to rounded-verrucate, ornamented with echinate and papillate projections and the exospore
was smooth (Fig.
Mature spores have a dense exospore
coat, a pale endospore, and single rows of 8-11 polar tubule coils (Figure 2, panels B, C).
3 cm, similar to lateral pinnae, with 1-2 basal lobules; rachis and costae stramineous to light brown, sparsely scaly, scales similar to rhizome scales; laminar tissue glabrous; veins reticulate, forming 2-3 series of areoles between costa and margin; sori round, located in (1-) 2 lines between costa and margin; sporangia glabrous; spores 47-51 x 28-38 pm, bilateral, ellipsoidal, convex to slightly concave-convex, exospore
prominently verrucate, verrucae 3-6.
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
Mature spores have a two-layered wall, with both perispore and exospore
, and their protoplast is fulfilled with lipid drops (Tryon and Lugardon, 1991).
The outer exospore
is then covered by the perispore.
volubilis was described by Tryon and Lugardon (1991) as papillate-rugulate, with scattered spherules on the surface and in section with a plain exospore
and a laminate 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.