“eo 
4 Che Orchid Review © 
5). VoL. XXVI. MARcH, 1918. No. 303, a 
lees | NOTES FROM KEW-III. aa 
CURIOUS experiment is in progress at Kew which is being watched 
with much interest. It arose as an attempt to find a potting material 
that was not subject to quick decay, with the accompanying loss of roots, 
and has thus been described by the Curator (Gard. Chron., 1918, 1. p. 51):— 
‘‘About three years ago half-a-dozen small plants were potted in 
ordinary sponge to test it as a substitute for peat fibre. Sponge, being 
clean and lasting, possesses in its other properties, so it was thought, 
exactly what epiphytic Orchids require. The result is interesting, the 
plants, having rooted freely in and about the sponge, the roots and leaves 
being quite healthy. Although the same sponge has been in use over three 
years, it is still tough and porous. The experiment is being repeated on a 
larger scale with Cattleyas, Dendrobiums, Vandas, Phalznopsis, Bulbo- 
phyllums, Stanhopeas, Odontoglossums, and Oncidiums. Sponge 
“trimmings” can be purchased at a reasonable price compared with the 
present price of osmunda fibre. Besides osmunda and all fern roots in use 
for the purpose break down too quickly, and are then mischievous.” 
It is suggested that “a plant pathologist in quest of a promising subject 
for research might give his attention to the behaviour of Orchid roots. 
Every experienced Orchid-grower has been troubled by the death of the 
roots of Cattleyas, Odontoglossums, Dendrobiums, and others, from no 
evident cause. It does not appear to be due to excess of moisture during the 
resting season, nor to drought. Since I have been connected with Kew, 
Odontoglossums have lost practically every root during the winter, even 
although the plants had filled their pots in summer with roots like a ball of 
twine. And it is the same to a large extent with Cattleyas. The annual 
loss of roots is accompanied by considerable shrinking of the pseudobulbs, 
so that when the plants begin to pick up in spring they have losses to 
recover before they can make new growth. It is not a question of soil, of 
that I am certain; but it may be one of atmosphere. There is poison 
enough in the air at Kew, and especially in winter, to cripple expanding 
flowers and foliage. Orchid roots are said to have a porous, paper-like skin 
which absorbs moisture from the air. Every part of the living root does 
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