12 



THE BOOK OF CHOICE FERNS. 



Eastern Europe. Though the genus has no British representative, yet the 

 most beautiful species, Onoclea (or, as it is usually called, Struthiopteris) 

 germanica, is stated by Correvon, in his " Fougeres rustiques " (p. 65), to 

 belong to the flora of Eastern and Central Europe, being found in Germany, 

 Austria, Scandinavia, Finland, Denmark, and Russia, as well as in Asia 

 Minor, Siberia, and as far as Kamtschatka. 



Culture. 



These plants require an abundance of water at the roots all the year 

 round, and are best adapted for planting out in the hardy rockery or 

 Fernery, as pots scarcely afford them sufficient accommodation for the full 

 development of their rhizomes or stolons, which, in some instances, extend 

 a very long distance. In the case of Onoclea germanica of Hooker, with 

 which Onoclea Struthiopteris of Hoffmann and Struthiopteris germanica of 

 Willdenow are identical, the plant is provided with stolons, which are said by 

 Sachs to originate from buds formed on the stalks near the base. These 

 organs run underground for several inches or a foot, then rise to the surface 

 and there thicken into a short, upright stem covered by overlapping stalk- 

 bases, and throw up from their summit a grand vase-like circle of foliage 

 composed of two distinct sorts of fronds — the barren ones, which are numerous 

 and produced early in the spring, and the fertile ones, which are few in 

 number and produced late in the summer. The fertile fronds are contracted, 

 much shorter than the others, and very rigid. 



The soil which Onocleas prefer is a compost of three parts of good strong 

 loam and one of leaf-mould. Great care should be taken that at all times 

 of the year their roots should be kept in a damp state. Some magnificently 

 cultivated examples of these Ferns exist at the Botanic Gardens, Cambridge, 

 where Mr. R. I. Lynch has had the good idea of planting them close to the 

 edge of a pond, with the result that 0. sensibilis rivals in size and majesty 

 the Royal Fern (Osmunda regalis) itself. 



Onocleas may be increased by means of spores, but their propagation 

 is effected usually by division of their underground rhizomes, or of their 

 stolons, an operation which, as the plants are of a deciduous nature, is best 

 performed when they are at rest, from October to March. 



