100 MISSOURI BOTANICAL GARDEN BULLETIN 
efficient source of mineral food supply. A fibrous mass 
of absorbing roots penetrates this decaying matter in all 
directions, while anchorage is maintained by means of 
other roots which seem to function in no other way. Plants 
collecting humus in this way have been termed “nest 
epiphytes. 
There are several other noteworthy epiphytic ferns in the 
collection—some, as Psilotwm triquetrum, growing on the 
trunks of tree ferns, others in the hanging baskets overhead. 
A discussion of epiphytic plants would be incomplete 
without mention of the copcat orchids. As a group they 
are essentially epiphytic, growing luxuriantly in most inac- 
cesable tree-tops, in the crevices of limbs, and indeed far out 
on the ends of branches. Besides being interesting from the 
standpoint of floral modification, the group attracts atten- 
tion by reason of the modifications which an aérial environ- 
ment has brought about in the functions of other organs. 
Notably is this true where the absorption of water is con- 
cerned. Many orchids send down long aérial roots, the cen- — 
tral cylinder alone of which is made up of living tissue, The 
thick coat surrounding this is composed of empty dead cells 
which absorb water very readily. As was true with the 
_ Spanish moss, water is taken in during rainfall and held in 
these empty cells which act as a reservoir. Orchids are not 
parasitic—they extract no nourishment from the tree upon 
which they live. When they anchor themselves, dead ma- 
terial accumulates in the mass of leaves and roots, which 
through its decay affords a mineral food supply to the plant. 
TWO RARE EPIPHYTIC GESNERIACEAE 
The family Gesneriaceae is familiar through the well- 
known genus Gloxinia (see April, 1915, number of the 
BULLETIN), species of which are extensively grown and a 
ood collection of which may be seen in the floral display 
ouse during the month of June. In the aroid house at 
the Garden, however, are two genera of Gesneriaceae which 
are so little known and so unusual that it seems especial 
attention should be called to them, i. e., Aeschynanthus and 
Columnea. : 
There are upwards of forty species of Aeschynanthus, 
most of which are natives of the East Indies. ‘They are 
found associated with orchids and other epiphytes, attach- 
ing themselves to the trunks and branches of trees by their 
roots which are freely produced from the trailing branches 
or stems. - ete 
