guished from P. conduplicata by its very much smaller 
size, by the type of its pubescence, and by several floral 
characters. 
IT. The identification of yoco 
Curiously enough, yoco has been given relatively little 
attention in anthropological and botanical writings. The 
sarliest attempt to identify yoco botanically was appar- 
ently that of Dr. Florent Claes of Brussels who made a 
trip to the Caqueta, Colombia, in 1925 to investigate 
yaje (Banisteriopsis spp.) and yoco. Dr. Claes made sev- 
eral excursions with Fray Gaspar de Pinell, then a Capu- 
chin missionary in the Putumayo-Caquetaé-Amazonas 
region, and succeeded in collecting a quantity of stems 
of yoco for chemical analysis and flowering specimens of 
the plant for taxonomic study. Fray Gaspar, writing in 
1929 of Claes’ work (Gaspar de Pinell: ** Excursi6n apos- 
tolica por los Rios Putumayo, San Miguel de Sucumbios, 
Cuyabeno, Caqueta y Caguan”’ (1929) 168), said (trans- 
lated): 
Dr. Claes was very much interested in trying to classify yayé and yoco 
with scientific accuracy; this was the main object of his trip. How- 
ever, since the flowers of these plants are almost microscopic, he had 
to content himself merely by collecting several specimens of them to 
examine under powerful microscopes... . Relative to yoco, he writes 
. A Gray . 7 
me the following: “The yoco is more than probably a member of or at 
any rate very near to the family amfelidias |sic].° 
The material which Claes took back to Europe for 
chemical studies was analyzed and the results were pub- 
lished before the accompanying herbarium specimens 
were identified. In 1926, Michiels and Denis (‘‘Sur la 
liane yocco, drogue a caféine du genre ‘Paullinia,’ ’’ Bull. 
Acad. Roy. Méd. Belg. sér. 5, 6, vii (1926) 424) referred 
yoco to the genus Paullinia. Later, however, de Wilde- 
man (‘‘Sur le yocco, plante a caféine originaire de Colom- 
bie*” Compte Rend. 1838 (1926) 1850) published a note on 
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