32 
BRITISH FERNS. 
retained round the root of the plant. Before they are 
returned to the greenhouse they should be well watered. 
Great care is required in watering greenhouse ferns; 
they must never be allowed to become dry, except on 
the surface, yet only a little must be given at once. 
Syringe them well in hot weather, taking care always 
to use rain-water. 
Of course air must be admitted daily and all day; 
at night also in summer. A covering of Shaw’s tiffany 
will be an advantage for hot sunshine. 
Greenhouse-ferns are subject to some diseases, or 
rather to the ravages of some insects. The syringing 
will prevent the scale; but if it has appeared before 
the means of prevention have been taken, recourse must 
be had to means of cure. Tobacco-wash is the best 
remedy for this, and if the vermin are very abundant 
the most infested fronds must be cut off and burned. 
The thrips may be kept down with tobacco- smoke, but 
if it gets ahead the ferns must be washed with tobacco- 
water and sulphur. Fumigation must be resorted to 
when mealy-bug appears. Several species of Adiantum 
flourish in our greenhouses, including our native species 
and the bird-footed one, described as a hardy fern. 
The most attractive greenhouse ferns are as follows :• — - 
The genus Drynaria is named from words signifying 
a tree ; it is allied to Polypodium , having no involucre, 
and the veins being crooked. The species live on woods, 
and often grow parasitically on the bark of trees. 
Drynaria Billardieri. BillardierP s Drynaria . Caudex 
widely creeping, fronds simple and pinnate. Sori large. 
A New Zealand species, very desirable in the green- 
house for its rapid growth ; it can be trained to cover 
damp walls or rock-work, or placed in pendent baskets. 
