58 The South Australian Naturalist. 



If this can be done experimentally at an elevation of less 

 than 450 feet, with full exposure to the north winds, it should 

 be possible, and will prove to be possible, anywhere on the 

 plains. Difference in rainfall counts little, as a heavy winter 

 rainfall is not relished by alpine plants, and the evening mist 

 kept up for an hour or two regularly is all they ask. 



As nearly all the alpine and rock garden plants are per- 

 ennials, there is little need for replanting. The care rather is 

 in controlling the ranker-growing plants and keeping the 

 weeds down. Seedlings come up so abundantly under rock 

 garden conditions that an abundance of material is always at 

 hand. 



This form of gardening has of late years become very 

 popular in Europe and America, and is a pleasant departure 

 from the yearly round of florists' flowers, providing, as it does, 

 continuous interest, owing to the great variety of small per- 

 ennials available, and the fact that there are plants flowering 

 the year round. I should advise anyone to get R. A. Malby's 

 little book called ''The Story of My Rock Garden" for direc- 

 tions and good advice. 



ORCHIDS GROWING FROM SEED. 



By Ernest H. Ising. 



Much has been written on the wonderful devices and 

 mechanisms possessed by orchids to secure cross-fertilization or 

 self-fertilization. Orchid seeds are exceedingly minute, and 

 one plant alone must shed hundreds of thousands or even millions 

 of seeds in one season. Yet, notwithstanding the marvellous 

 schemes for securing the setting of the innumerable seeds, the 

 plant, it is believed, almost invariably propagates itself by its 

 underground root system — false bulbs or tubers. 



Dr. R. S. Rogers has written (1) on the pollination mechan- 

 ism and seed production of certain orchids, and concludes that 

 ''Some of these seeds doubtless survive and germinate, but the 

 vast proportion of them must perish. Many attempts have been 

 made to cultivate them artificially, but, so far as the writer can 

 ascertain, such attempts have been unsuccessful. Very little, 

 indeed, is known about this mode of propagation. ' ' Writing of 

 seedling orchids, Mr. E. E. Pescott, F.L.S., F.R.H.S., says (2) : 

 "I have never yet seen anywhere what I could faithfully deter- 

 mine to be a seedling terrestrial orchid." It would seem from 

 these two statements that seedling orchids are a very rare occur- 

 rence, and I believe this is true generally of orchids. But I have 

 what I regard as a splendid proof of seed propagation. 



