CHAPTER XLVII 



VITTARIOID FERNS 



There is no habit that produces a more marked effect upon the structure 

 of plants, and on Ferns in particular, than the epiphytic, often closely 

 related as it is to a rupicolous habit. The genera that group themselves 

 round Vittaria show this in high degree, and the effect extends to both of 

 their generations. But since other Ferns are liable to similar modifications 

 under like conditions, it is natural that there should have been difficulty in 

 distinguishing the Vittarieae s}'stematically from these homoplastic rivals. 

 Few groups of Ferns have suffered more than they under this difficulty: 

 for their creeping habit, simple anatomy, leathery unbranched leaf, of linear 

 or ovoid form, frequently with sori that give the minimum of distinctive 

 features, throws back diagnosis upon a balance of apparently minor cha- 

 racters. It is this which has led to the checkered systematic history of the 

 Vittarieae (compare Diels, Natilrl. Pflanzcnfani. Fig. 157). The vicissitudes 

 of their classificatory history need not be traversed here, for they are fully 

 recorded by Von Goebel {Flora, 1896, p. ^-j), and by Williams {Trans. Roy. 

 Soc. Edin. 1927, p. 173). It must suffice to say that it was the former who 

 suggested grouping together under the heading of the Vittarieae the five 

 genera, Vittaria Sm\\h,Monogramme Schk.,Antrophyic7n ¥^3i\Ai.,Hecistopteris 

 J. Smith, and Anetiutn (Kunze) Splitgerber, which are now included. He 

 excluded Pleurograinme BL, and other superficially like, but actually homo- 

 plastic Ferns. It may now be held that those five genera form a homo- 

 geneous group, which is characterised by a creeping rhizomatous habit, 

 with alternate leathery leaves of simple outline: by the presence of spicular 

 cells in the epidermis, and an absence of sclerenchyma: by clathrate scales: 

 a relatively simple vascular system : sporangia and paraphyses borne upon 

 or sunk deeply into the leaf-surface: numerous annular cells, and a well- 

 marked stomium. The gametophyte, where known, is of aberrant form, 

 frequently bearing gemmae. 



Vittaria Smith 



The name-genus of the Family comprises epiphytic Ferns with narrow 

 grass-like leaves, their venation being reticulate without free vein-endings. 

 The rhizome, which forks occasionally, bears clathrate scales: it is almost 

 solenostelic, the wide leaf-gaps overlapping slightly. The transverse section 

 shows a gutter-shaped stele, with internal and external phloem and endo- 



