The mid-styled form of Piaropus paniculatus 
AiceE M. JOHNSON 
(WITH TWO TEXT FIGURES) 
Certain species of the Pickerel Weed Family (Pontederia 
cordata and rotundifolia) are completely trimorphic, while other 
species are, as far as is known, incompletely trimorphic. Thus, 
for Piaropus azureus (Sw.) Raf., only the short-styled and long- 
styled forms are known, for P. crassipes (Mart.) Britton only 
the long-styled and mid-styled forms have been reported, and 
for P. paniculatus (Spreng.) Small only 
the mid-styled form has been observed 
to date (see Fic. 1). 
At least for P. paniculatus seed pro- 
duction is not uncommon. In the 
spring of 1920 Professor Tracy E. 
Hazen gathered seed from the single 
form of this species growing in the 
Royal Botanical Garden in Trinidad. 
Plants from this seed grown at the 
New York Botanical Garden also pro- 
duced seed. The natural production 
of seed in this one form raises the Fie. 1. Drawing of corolla 
question whether there are here any of flower of P. paniculatus 
limitations to fertility and seed pro- °Pened out to show relative 
duction such as have been considered a 
pistil and the two sets of sta- 
characteristic of trimorphic species (see mens (x 3). 
especially Darwin, 1865 and 1877, for 
Lythrum Salicaria). It is obvious that in the production of 
seed by plants of only the mid-styled form, asin P. paniculatus, 
there is no opportunity for legitimate pollinations, such as exist 
when two or three different forms are growing together. There 
is, however, opportunity for discriminative fertilizations in- 
volving the two sets of stamens either in selfing or in crossing 
and also for variation among plants either in self-compatit ility 
or in cross-compatibility. It was to determine these points that 
the investigation here reported was undertaken. 
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