271 



pendent upon the gametophyte. The young stem and primary root show a 

 single apical cell, which is probably replaced by a group of initial cells in the 

 massive stem and roots of the mature sporophyte. The cotyledon in Marattia 

 is forked like that of the typical Ferns ; but in Angiopteris and Dansea it has a 

 midrib and pinnate venation. 



The Mature Sporophyte 



All of the existing Marattiacese are tropical. The stem in Angiopteris and 

 Marattia is a nearly globular massive body, covered with the thick persistent 

 stipules of the leaf-bases. 

 In Danaea the stem is 

 prostrate, but otherwise 

 much like the other gen- 

 era. The leaves, which 

 are fleshy in texture, are 

 smooth, and coiled up 

 when young. 



Histology. As in 

 the Ophioglossaceae, the 

 ground - tissue is prin- 

 cipally composed of 

 parenchyma, but scle- 

 renchyma (Fig. 237) 

 occurs in the stem and 

 larger leaf-stalks. It 

 may, however, be re- 

 placed by thick-angled 

 tissue (collenchyma). 

 Conspicuous mucilage- 

 ducts (Fig. 238) closely 



vb 



resembling those in the 

 Cycads, occur abun- FIG. 237. Danssa alata. A, sterile pinna, attached to 

 dantly in the ground-tis- the winged rachis, r (x 14). B, under surface of a 

 fertile pinna, showing the synangia, sp. C, cross- 

 section near the base of the petiole ( X about 6) ; 

 scl, sclerenchyma ; m, mucilage-ducts; vb, vascular 

 bundles. 



sue, and cells containing 

 tannin are of common 

 occurrence. The vascu- 

 lar bundles (Fig. 238) 

 are concentric and not strikingly different from those of the Leptosporangiates. 



The Sporangia. The sporangia (Fig. 239) are more or less completely 

 united into synangia, in which the outlines of the individual sporangium are 

 quite lost. In Angiopteris and Archangiopteris the individual sporangia can be 

 recognized, and they possess an imperfect annulus. The sporophylls may be 

 quite unmodified as in Angiopteris and Marattia, or contracted, and the whole 

 lower surface almost completely hidden by the crowded synangia (Fig. 237, B). 

 In all cases they are borne upon the lower surface of the sporophyll. The 

 sporangium, or each loculus of the synangium, opens by a longitudinal slit, or 

 pore. 



Of the existing genera, Marattia is cosmopolitan ; Angiopteris occurs in the 

 eastern Tropics ; Kaulfussia is East Indian, and Dansea is American. The re- 

 cently discovered Archangiopteris comes from southwestern China. 



Fossil Marattiaceae. Many fossil Ferns are known which are allied to the 

 living Marattiacese, and it is evident from a study of these fossil forms that the 



