158 Hill. — A Revision of the Geophilous Species of Peperomia. 
Geographical Distribution. 
The geophilous species form a very natural biological group, and 
their respective habitats seem to be fairly well defined. Too great stress 
must not be laid in all cases on the underground tuber as a guide to 
the relationships of different species, since the external features of any 
of these plants appear to depend largely on the conditions of their particular 
habitats. The pai'vifolia group, however, does seem to be a very natural 
one, for not only do the several species show affinities in numerous points, 
but they occur in a fairly definite line from about io°-i8° S. latitude. 
P. minuta is the most northerly species, and is succeeded by P. verfn- 
culosa in the regions from Oroya to Cuzco ; P. parvifolia occurs around the 
southern end of Lake Titicaca, and P ..cyclaminoides, which perhaps is not so 
closely related to the other three species, has been found in the mountains 
of Southern Bolivia near Tarija. They all show well-marked xerophytic 
characters, and apparently live in exposed places. Under such conditions 
the roots from the base of the bulb, growing more or less vertically down- 
wards, would be able to obtain water from soil at some depth below the 
quickly drying surface. 
The other South American species are more distinctly shade plants, 
with a fairly large leaf lamina, thin and membranous in texture when dried, 
and the walls of their fruits are delicate and apparently contain chlorophyll. 
Of the four well-known species of that group, P. umbilicata , P. peruviana , 
and P. falsa are no doubt closely allied. Their bulbs, with lateral and 
horizontally running adventitious roots, are similar in character. P. Gau- 
dichaudii , however, in its campylotropous bulb, is a very distinct form, 
though in other respects it shows fairly close relationship to P. umbilicata. 
With the Mexican campylotropous species P. Gaudichaudii appears to 
have only a biological connexion, since it differs from them both in leaf 
and floral characters, and it seems most likely that a similar biological adap- 
tation has arisen independently in the two widely separated localities. 
Of the species just mentioned, P. peruviana appears to have the most 
extended range, namely from the vicinity of Urubamba in Peru in the 
north to the south of Bolivia, and to the province of Salta in the Argen- 
tine, whilst P . Gaudichaudii appears to be restricted to relatively low 
country (200-800 m.) 1 in the neighbourhood of Lima. 
The Central American and Mexican species are recorded from Costa 
Rica (P. ovato-peltata), Guatemala (P. claytonioides, P. pinulana, P. pedi - 
cellatd , P: bracteata), and from Mexico to about as far north as lat. 2S° N. 
P. monticola , from the region of S. Luis Potosi, is the most northerly 
1 Weberbauer’s No. 2013 from the Province of Tarma, Dept. Junin, 1900-2000 m. in the 
mountains above Lima, may perhaps belong to this species. 
