260 THB FERNS OF LORD HOWE ISLAND, 



iv. Ophioglossum. 

 In my paper on ''The Ferns of Lord Howe Island," I recorded 

 Ophioglossum vulgatum L., as new to the Island. Since then, I 

 have gone carefully into the question of the geographical distribu- 

 tion of this remarkable plant. Christensen, in his Index Fil., fol- 

 lows those w^ho exclude 0. vulgatum from Australia, limiting it to 

 "Europe. Madeira, Amer. bor., Asia occ," and assigning to Aus- 

 tralia and New Zealand several distinct species, as follows: 0. 

 Biefrichice Prantl, 0. Prantlii C. Chr., {0. lanceolatum Prantl), 

 0. costatum R. Br., 0. Luersseni Prantl, 0. minimum Hook, fil., 

 O. coriaceiim A. Cunn., (0. gramineum R. Br.), and 0. peduncu- 

 losum Desv. My Lord Howe specimens, therefore, had to be re- 

 examined. Tlie result has been to convince me that tlie supposed 

 Australian si^ecies show" so few decided differences from 0. vulga- 

 tum as to be indistinguishable, except as varieties, or even forms. 

 In this, I follow C. Luerssen, wlio, in the Journ. Mus. Godeff., iii. 

 233ff(1875), subjected the genus to exhaustive examination and 

 figured the various Australian forms with much patience. Domin 

 also, in his ''Beitriige zur Flora und Pflanzengeographie Austral- 

 iens," Vol i., accepts the findings of Luerssen. The fact is, the 

 apparent differences are not constant. Lueressen shows, it seems 

 to me conclusively, that no distinctive specific characters are to be 

 found in («) the number of leaves springing from one rhizome, 

 {b) the length of the common stipes, (c) the form of the sterile 

 leaf-section, {d) the relation between the sterile and fertile 

 parts, (e) the vascular formation of the stipes, (/) the num- 

 ber of the sporangia and the form of the sterile apex, (g) the 

 nervature of the sterile part of the leaf, (h) the form of the sur- 

 face-cells of the sterile leaf-section, (i) the presence or absence of 

 a central nerve, (k) the shape and character of the spores. Where 

 the variations are so marked, and the different forms run into one 

 another so freely, it would seem preferable to give the name 0. 

 vulgatum L., to all the specimens, with some indication of the 

 general form of the plant collected, such as is attempted in the 

 names "gramineum'' and "lanceolatum." For the present, I re- 

 cord the Lord Howe si^ecimens as O. vulgatum L., var. lanceolatum 

 Luerss. 



