NORTH AMERICAN PIPERS OF THE SECTION OTTONIA^ 
William Trelease 
(Received for publication December 9, 1920) 
The woody Piperaceae, with 2-5 unfimbriate stigmas, comprise the 
better part of 1,000 species, the extremes of which differ greatly while the 
segregation of those that are closely related is very difficult. The structure 
and numerical plan of the minute flowers run over so large a range of dif- 
ferences that it seems quite unreasonable to include them all in a single 
genus; but however the lines be drawn, the segregates remain too hetero- 
geneous and laxly characterized to give satisfaction. Even as subgenera or 
sections of the single genus Piper, this is true of them.. 
When Casimir de Candolle monographed the family, half a century 
ago, he admitted several such subdivisions of Piper (i), and with various 
emendations these are kept up in most of his publications during the two 
generations through which he has been accorded by common consent the 
title of master in this field. Shortly before his death, however, in a manu- 
script (2) on the Central American representatives of the genus, his ex- 
pressed views on this point underwent modification to the extent of assigning 
to a distinct section, Ottonia, the species with pedicellate flowers which he 
had placed formerly partly in the section Enckea and partly in the section 
Steffensia. This section corresponds to Sprengel's genus Ottonia, of 1820; 
the type of which is the South American Piper Jahorandi. 
Though M. de Candolle monographed the West Indian Piperaceae (3) 
eighteen years ago and subsequently added descriptions of occasional 
novelties, and made a reexamination of the Isthmian and Central American 
species of Piper when preparing the manuscript of which parts have been 
published within the past year (4) , no effort has been made to consider the 
Mexican species collectively since Hemsley included them in his tabulation 
of the Central American flora nearly forty years ago. Indeed, in the whole 
large genus, only two Mexican species (5) have been described during the 
past generation. 
Among a considerable number of undetermined Pipers at the New 
York Botanical Garden and in the United States National Herbarium, which 
Dr. Britton and Mr. Maxon have permitted me to study preliminary to a 
general revision of the North American representatives of the family, 
several interesting Mexican novelties in the pedicellate section Ottonia 
occur. The analysis of these which follows may serve to illustrate the 
^ Read before the Taxonomic Section of the Botanical Society of America, at Chicago, 
December 29, 1920. 
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