330 Dr. G. Ogilvie on the Vascular and Woody Tissues of Ferns. 



to the external characters of the rhizomes, as explained in my 

 former communication on this subject (Ann. Nat. Hist. Dec. 

 1859). 



Rootstock a stoloniferous rhizome. 

 Polypodium vulgare. Adiantum Capillus Veneris. 



Dryopteris. Hymenophyllum Tunbridgense. 



Phegopteris. Wilsoni. 



Lastrea Thelypteris. Trichomanes radicans. 



Pteris aquilina. 



Rootstock a dichotomous caudex. 



Polypodium alpestre. Asplenium viride. 



Polystichum Lonchitis. trichomanes. 



Lastrea Oreopteris. Ruta muraria. 



rigida. septentrionale. 



Cystopteris fragilis *. Woodsia Ilvensis. 



Athyrium Filix foemina. Allosorus crispus. 



fontanum. Scolopendrium vulgare. 



Asplenium Adiantum nigrum. Ceterach officinarum. 



lanceolatum. Blechnum boreale. 



marinum. Osmunda regalis. 



Rootstock a right caudex (extending by a single terminal bud). 



Polystichum aculeatum. Lastrea cristata. 

 Lastrea Filix mas. Botrychium Lunaria. 

 dilatata. Ophioglossum vulgatum. 



EXPLANATION OF THE PLATES. 



Plate V. 



Fig. 1. Cross section of the rhizome of Osmunda regalis, showing the 

 brown cortical substance and the pale tissue within, surrounding 

 the central vascular cylinder with its cellular pith, and a cambium- 

 layer only on its exterior : a a, origins of the petioles ; b b, root- 

 lets. (The outer tissue has been partially pared away, to fit the 

 specimen into the section instrument.) 



Fig. 2. Cross section of a petiole near the base, showing the cut extremities 

 of the longitudinal filaments and of the crescentic fasciculus and 

 dark band. The asterisk in this and the other sections of petioles 

 marks the side next the rhizome — that which is uppermost when 

 the frond is laid on its back. 



Fig. 3. The central vascular cylinder of the rhizome of O. regalis dissected 

 out, showing the imbricated fasciculi going to the petioles. 



Fig. 4. A portion of the netted cylinder of Lastrea dilatata opened out, 

 showing the origin of the petiolar fasciculi. 



Fig. 5. Cross section of the rhizome of Blechnum boreale, showing the 

 great development of dark tissue in this stem. The outer series 

 of fasciculi (in pairs), a a a, belong to the origins of the petioles ; 



* The other British forms of Cystopteris are questionable species ; but 

 if Mr. Newman is correct in assigning to C. montana a " stoloniferous 

 rhizome " (History of British Ferns, p. 97), this may perhaps be a good 

 species. 



