212 



PTERIDOPHYTA. 



Three genera with about twelve species. 



Order 2. Marattiacese are tropical Ferns, whose gigantic 

 leaves resemble those of the Polypodiacese, but have stipules in 

 addition. The sporangia are grouped in sori, situated on the lower- 

 side of the leaves, the sporangia in each sorus being arranged 

 either in two rows or in a ring. In Angiopteris they are isolated 

 (Fig. 210 A), but in the other species (Kaulfussia, Dauct>a, Marattia\ 

 they are united, and form " synangia " divided into a number of 

 chamber's corresponding to the sporangia. These open by clefts 

 or pores. Marattin presents the highest development, as its 

 sporangia are completely united in a capsnle-like synangium, 

 which is closed until maturity, and then opens by two valves. 

 In each valve there is a row of three to eleven sporangia, each 

 opening by a slit towards the inside (Fig. 210 B, C). An indusium 

 encloses the sorus, except in Kanlfussia ; it is formed of flat and 

 lobed hairs, which resemble the hairs of the other portions of the 



leaves. In Angiopteris and Mar- 

 attia the indusium is very rudi- 

 mentary ; in Dancea it forms a 

 kind of cupule. 



The numerous fossil Marattiacete 

 (15 genera, with 98 species) present 

 similar differences to those now living, 

 but more various forms are found, for 

 example, with solitary free sporangia. 

 Those now living are the last small 

 remnant (4 genera with only 23 

 species) of a once dominant family, 

 which existed from very early times, 

 and whose culminating point was 

 reached in the Kulm and Coal periods. 



The Ophioglossaceas appear also in 

 the Kulm and Coal periods, and were 



FIG .210. Sporangia of the Marattiaceae : 

 .4 Angiopteris; B and C Marattia ; C is a 

 half sorus with nine sporangia, each of 

 which has opened by a longitudinal cleft. 



about as numerous as at the present time (presumably 2 genera, with 19 

 species). Leptosporangiate Ferns appear however to have occurred first of all 

 in the Trias-formation. 



Family 2. Leptosporangiatae. 



Order 1. Polypodiaceae. Sporangia on the lower side of the 

 leaves, stalked and provided with a vertical, incomplete annul us ; 

 dehiscing by a transverse cleft (Fig. 211 !>). The genera are 

 distinguished by the form of the indusium and the position of 

 the sori, etc. 



