NOVEMBER, I9QITI.] THE ORCHID REVIEW. 327 
CYPRIPEDES ON LIMESTONE, 
Last year you published some papers by Dr. Miles Johnston upon Cypri- 
pedium growing (O. R., xviii., pp. 193-198, 225-230). In these papers—of 
exceptional interest and acumen—Dr. Johnston builds and banks heavily 
upon the use of limestone or mortar drainage. He confesses his ignorance 
of the habits of some species, and only claims a probable limestone habitat 
for all or most species. It may be of interest to him, and to your readers, 
for me to confirm that two of our best species, Paphiopedilum Haynaldianum 
and P. philippinense (the old and always attractive Cypripedium levigatum) 
are found strictly upon limestone rocks, and nowhere else. The former is 
found in a very shallow and, strangely enough, adhesive yellow clay. It 
seemingly acts merely as a support for the stem, as the roots quickly pierce 
it down to the stone substratum. The second species occurs upon nearly 
vertical cliffs of very pure and hard limestone. There is practically no soil 
whatsoever, and these cliffs are quite devoid of any other vegetation than a 
dwarf and scrubby polypodium, with the roots of which those of the 
Cypripedes are mingled. 
Both plants occur in deep narrow rifts or clefts in the rock, and the 
roots of the slippers find their way to the bottom, often going down toa 
depth of two to three feet. In the bottoms of these crevices is a thin 
accumulation of humus, the detritus of the decomposing leaves of the 
slippers and ferns. As these crevices are sharply tilted, they are scoured by 
our torrential rains, so that this residuum of food is often a scanty film. 
I have a few plants of these two species growing in the conventional 
compost, upon a drainage base of this living (?) stone, and they are in 
excellent form and vigour. As limestone (unburned) is scarce and inaccessible 
in this locality, I have other plants where bits of mortar have been substi- 
tuted, and must say that the results are unsatisfactory or worse. 
It may be of interest to know that some of these cliffs have a nearly 
southern exposure, and in April and May—our hottest season—the plants 
are exposed to the full force of the sun till 3 to 4 p.m., the mean daily 
temperature maximum at that season approximating go°-g2° F., and 
occurring between 2 and 3 p.m. Nevertheless, the leaves at this season 
remain a brilliant green and rarely become flaccid. I cite this to illustrate 
how little after all we can utilise a knowledge of plant environment when 
we come down to their cultivation under restraint of any kind. Under pot 
culture, with like climatic conditions, and under a like sunny exposure, in 
ten days we would reduce them to cinders, or if water enough were used to 
prevent this, then to pulp. 
Ws. S. Lyon. 
Gardens of Nagtajan, Manila. 
