156 PLANT PROPAGATION 
for decorating are propagated by division in spring, and 
grow well in a cool house in sun or shade. 
OrcHIDS.—Owing to the different habits and manner 
of growth of these gems among flowering plants, some 
can be easily, if not rapidly, increased, while with others 
the process is very slow. With Dendrobiums, Cattleyas, 
Calanthes, Cymbidiums, Cypripediums, Masdevallias, 
and many other genera, the most usual method is by 
division of the pseudo-bulbs or side-growths, which is 
successfully practised just as growth is about to com- 
mence. Formerly the fertilisation of Orchids and rais- 
ing them from seed were rarely carried on, but these 
operations are now common with growers who make a 
speciality of their culture. The raising of seedlings 
presents problems of interest not only to the gardener, 
but also to the biologist. By some it was observed that 
the minute seeds germinated and grew better when sown 
on the surface of the compost in which a parent plant 
was growing. It is now understood that with the roots 
Orchid Mycorrhiza, a fungus, grows in symbiosis or 
beneficial partnership analogous to that observed in 
Lichens, and unless this is present in the compost 
growth is unsuccessful. From that discovery we learn 
that some compost or pieces of roots from established 
plants should be mixed with the material used when 
sowing the seed, to insure the presence of the Mycor- 
rhiza for the mutual benefit of the partnership. In their 
native habitats, seedlings of some species in all stages 
of growth may be seen growing on the débris collected 
in the chinks of rocks and branches of trees. Cultivators 
here in some measure imitate this by filling pans with 
the débris from peat and moss, making it wet and 
scattering the seeds thereon. It must not be allowed 
