CULTIVATION. 
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grown in a temperate house ; of which Polysticlium 
aculeatum, Lastrea dilatata, and L. Filix-mas may be 
cited as examples, as also Asplenium marinum. In 
1820 I found plants of it, having fronds from 2-4 
inches in length, growing in a cave facing the German 
Ocean, on the east coast of Scotland ; of these, two 
plants have been grown at Kew from that time ; of 
late years, one in the Temperate and the other in the 
Tropical House. These became fine caespitose plants, 
with fronds varying from 1-1 1 foot in length; the 
greatest length being attained by the plant in the 
Tropical House, even assuming the character of a 
species native of the West Indies and Tropical 
America, and quite unlike the original plant; thus 
showing that although at home in the cold, sunless 
cave, it can well appreciate a better fed and warmer 
abode. Exceptions to this rule are some alpine 
species. Ferns in that respect being analogous to our 
ill success in growing many alpine flowering plants. 
This is no doubt partly owing to the difference of 
atmospheric density, and the varying influences of 
temperature and moisture common to the sea-level of 
this climate. 
The species of cold climates truly deciduous, produce 
their fronds from an underground creeping sarmentum, 
of which Pteris aquilina, Sitolobium punctilobium, 
Onoclea sensibilis, Anchistea virginica , Lorinseria areo- 
lata, Leucostegia immersa, and Phcgopteris aurita are 
the principal examples. On the other hand, instances 
of tropical species periodically losing their fronds 
without any apparent cause, such as by undue excess of 
heat and moisture, are Pliymatodes oxyloba, Pleuridium 
palmatum, P. venustum , Drynaria propinqua , several 
