PTEROPSIDA 129 



19F). The sori were commonly arranged in two series along 

 the pinna, as illustrated in Fig. 19E, each associated with a 

 veinlet in the lamina. Scolecopteris was similar, except that 

 the sorus was elevated on a short pedicel, or receptacle 

 (Fig. 1 9 A). In Acitheca, the sporangia were elongated and 

 pointed and were arranged round a central plug-hke recep- 

 tacle (Fig. 19C). Eoangiopteris is regarded as a more advanced 

 type of sorus^^ since it was Hnear instead of radial. Each had 

 a cushion-like receptacle, on which were five to eight 

 sporangia (Fig. 19B). In all these genera, the sporangium 

 wall was very massive, many cells thick, and the number of 

 spores Hberated from each was very high, e.g. up to 2,000 

 in Aster otheca parallela. 



Fronds of these various types are often found in associa- 

 tion with stout trunks that bore a superficial resemblance to 

 those of modern tree-ferns, some of them as much as 15 m 

 high, but organic connection between fertile frond and 

 trunk has not yet been demonstrated conclusively. The 

 evidence, nevertheless, suggests that Asterotheca fronds were 

 borne in a crown at the summit of trunks known as 

 Psaronius. Many species, belonging to a number of sub- 

 genera of Psaronius, are known and most of them had 

 remarkably complex stelar anatomy. Some of them were as 

 much as 75 cm across, but most of this width was occupied 

 by a thick mantle of roots, for the single stem in the centre was 



sorus. Angiopteris : G, h, sorus of A. crassipes; o, s, vascular 

 system oiA. evecta ; w, young embryo ; x, older embryo. Marat tia : 

 I, J, sorus ofM.fraxinea; Q, pinna; t, prothallus of M. Douglasii; 

 u, archegonium. Danaea: k, l, sorus of D. elliptica; r, pinna; 

 Y, embryo. Christensenia: m, n, sorus of C. aesculifolia ; p, 

 pinna ; v, rhizome with leaf base 



(1, stipule; 2, stipular flange ; 3, flange of lamina; f, foot; 1, leaf; 

 r, root; s, suspensor; x, stem apex) 



(a, b, f, after Mamay; c, Scott; d, Brogniart; e, Hirmer; g-n, 

 p-R, Bower; o, s, Shove; t, u, y, Campbell; v, Gwynne-Vaughan ; 

 X, Farmer) 

 £ 



