THE ORCHID WORLD. 



[June-July, 1916. 



OAK AND BEECH LEAVES. 



THE practice of including a proportion 

 of leaves in the potting compost has 

 long been found an advantageous 

 method of supplying the necessary food 

 material for young and fast-developing seed- 

 ling Orchids. Even with fully-grown plants 

 the plain peat and other fibres do not always 

 yield the required amount of food, and addi- 

 tional matter is supplied by means of clean 

 leaves, gathered as they fall m the autumn 

 months and stored until needed. Expert 

 growers invariably recommend the use of 

 oak or beech leaves, no doubt because experi- 

 ence proves that these take much longer to 

 decay than others, hence their special value in 

 maintaining the compost in a firm condition. 



But there is something more to learn about 

 the true value of the above-mentioned leaves. 

 Unlike other trees, whose leaves give up most 

 of their food material before falling off in the 

 autumn months, the leaves of the oak and 

 beech have the unusual habit of preserving 

 in themselves certain substances which are of 

 undoubted assistance to the rapid growth of 

 seedling Orchids. Dr. Fred. Keeble, in a 

 lecture on Plants and the Rhythm of the 

 Seasons delivered before the members of the 

 Royal Institution, alludes to this interesting 

 subject, and from the report published in the 

 Gardeners' Chronicle, May 13th, 1916, we 

 extract the following paragraphs : — 



" The fall of the leaf is no mere mischance 

 due to the sudden breaking of a stalk rendered 

 brittle by the drying of the sap. Weeks before 

 the leaf falls preparation is made for this act 

 of self -amputation, and the wound which is to 

 be made is healed in advance. Cells in the 

 stalk begin to grow again, and resume the 

 power of division which they possessed in 

 their youth. On the side near the base of the 

 stalk they form a layer of corky tissue, but 

 beyond this layer they form a plate of thin- 

 walled cells, and this work is taken in hand 

 long before the leaf must fall. The corky cells 

 shut off all the leaf beyond from the reach of 

 water. Thus the leaf withers, the thin-walled 

 cells dry and break apart, and the leaf is held 

 by a mere thread composed of the woody 

 vessels which run along the stalk. These 



vessels become so choked with gum and so 

 brittle that a breath of wind suffices to detach 

 the leaf and bring it to the ground. 



" Yet before this self-amputation of each 

 leaf is effected other changes preparing for its 

 death have occurred in the leaf. Much of the 

 useful material contained therein becomes 

 dissolved and travels along the stalk, to be 

 stored in the young buds, or near by. 



" It is a curious fact that whereas most of 

 our broad-leaved trees discard their leaves by 

 the formation of this peculiar absciss layer, 

 the beech and oak do not. Hence it is that 

 their leaves hang longer on the trees, per- 

 sisting in sheltered spots even until spring, 

 and it is no less curious that it is the leaves 

 of oak and beech which make the best leaf- 

 mould. This may perhaps be due to the fact 

 that the leaves of these two trees not only do 

 not practise self-amputation, but also do not 

 go through the preliminary emptying-out 

 process, and hence contain more salts and 

 more organic matter than is left in the withered 

 leaves of other trees." 



Orchid Catalogue. — Messrs. Flory and 

 Black have issued an interesting catalogue 

 of their stock. It contains a large number of 

 desirable things, and is particularly note- 

 worthy for the fine selection of Brasso- 

 Cattleyas, Brasso-Laelio-Cattleyas, Sophro- 

 Cattleyas, Laelio-Cattleyas, etc., enumerated. 

 The choice and varied selection of the above 

 offered in an unflowered state speaks highly 

 for the progressive and up-to-date character 

 of this firm, and the high quality of the novel- 

 ties exhibited from this collection at the Royal 

 Horticultural Society's exhibitions is a safe 

 criterion of what may be expected. We can 

 see no finality to the production of finer and 

 still finer hybrids, and) on reading through the 

 lists of the unflowered crosses in this cata- 

 logue we were much impressed with the 

 intelligently made combinations. 



Holland House Show. — The Royal 

 Horticultural Society will hold its Summer 

 Show at Holland House, Kensington, on 

 Tuesday, Wednesday and Thursday, July 4th, 

 5 th and 6th. 



