XX] MARATTIALES 317 



Angiopteris. This genus occurs in Polynesia, tropical Asia, and Mada- 

 gascar ; it is characterised by a short and thick fleshy stem bearing large 

 bipinnate leaves which occasionally show a forking of the rachis^, a 

 feature reminiscent of some Palaeozoic fern-like fronds. One of the 

 large plants of Angiopteris evecta in the Royal Gardens, Kew, bears leaves 

 12 feet in length with a stalk 6 inches in diameter at the base. The 

 sessile or shortly stalked and rather leathery linear or broadly lanceolate 

 pinnules have a prominent midrib and dichotomou.sly branched lateral 

 veins. The surface of an old stem is covered with the thick .stumps of 

 petioles enclosed by pairs of fle.shy stipules (fig. 241, A) and bears 

 numerous fleshy roots, which hang free in the air or penetrate the .soil. 

 The young fronds (fig. 220, A) exhibit very clearly the characteristic 

 circinate vernation. The proximal part of each primary pinna is cha- 

 racterised by a pulvinus-like swelling. The sporangia, in short linear 



Fio. 241. A. Angiopteris evecta. (Cousiderablj' reduced.) 

 B. Marattia fraxinea. Stipule. M.S. 



elliptical sori near the edge of the pinnules, consist of free sporangia 

 (fig. 242, A — D) provided with a peculiar type of "annulus "2, in the form 

 of a narrow band of thicker-walled cells, which extends as a broad strip 

 on either side of the apex. An examination of sections through the 

 sporangia of Angiopteris in different planes'' illustrates the difficulty of 

 determining the precise nature of the annulus in a petrified sporangium 

 which is seen only in one or two planes. Many of the sporangia from the 

 English Coal-Measures, compared by authors with those of Leptosporangiate 

 ferns, are in all probability referable to the Marattiaceous type. 



The vascular system* of the stem constitutes a highly complex dictyo- 

 stelic or polycylic type which may consist of as many as nine concentric 

 series of strands of xylem surrounded by phloem, with large sieve-tubes 



^ Observed in plants in the Botanic Gardens of Brussels and Leipzig. A.C.S. 



2 For an account of the spore-producing members of the Marattiaceae, see 

 Bower (97). 



3 Zeiller (90) p. 19. * Shove (00) ; Tansley (08). 



