150 AMERICAN JOURNAL OF BOTANY [Vol. io, 
culture began producing sex organs early in the spring (1921) and produced 
great numbers of antheridia and archegonia until December, except during 
the hot summer months when the plants grew but little and appeared 
about to succumb. Numerous attempts to obtain functional antherozoids 
resulted only in the discharge of imperfectly formed, non-motile, coiled 
bodies. A few female plants with archegonia were fixed late in December 
and showed disintegration of the axial row before the maturing of the arche- 
gonium. No sporophytes have appeared in these cultures. 
The form of the antheridial branches in these cultures was noticeably 
different from that of the antheridial branches of plants collected in the 
vicinity of Madison. These branches in the Florida material grown in the 
greenhouse were borne in groups of three (rarely five) as figured by Mac- 
Vicar (1912, p. 50). The individual branches were short and wide, with 
thin upturned or inrolled margins. The antheridia were arranged rather 
irregularly. Representative plants were sent early in the spring (1921) to 
Professor A. W. Evans. He wrote that “the male branches are certainly 
very peculiar and I have never seen anything quite so indefinite among 
the various specimens of Riccardia which I have studied.” He also com¬ 
mented upon the wide distribution of this species and suggested that “under 
the circumstances a considerable range of variation is to be expected.” 
The antheridial branches produced in these cultures from early spring 
to December showed no significant variations in form; but a few male plants 
sent by Mr. Rapp from the same locality in Florida and received October 8, 
1921, bore antheridial branches so different from those of the Florida plants 
grown in the greenhouse that they might easily have been taken to be of 
a different species. The plants in this latter shipment bore antheridial 
branches ranging up to four or five millimeters in length, very uniform 
in width from base to tip, and with two (occasionally four) alternating rows 
of pits from which the antheridia had disappeared and which were arranged 
with almost mathematical regularity. Miss Clapp (1912), working on 
material collected at Xalapa, Mexico, described the arrangement of the 
antheridia on the branches as “extremely regular, in two alternating rows 
corresponding to the segments of the apical cell.” The appearance of the 
plants in this latter shipment from Florida is certainly in accord with her 
description. In those branches having four rows of pits it seems evident 
that each branch had possessed two apical cells, the segments from each 
apical cell having given rise to two rows of antheridia. In the plants col¬ 
lected in the vicinity of Madison, the antheridial branches are generally 
borne singly, are relatively short and wide, and show little regularity in the 
arrangement of the antheridia (text fig. 1). It seems probable that the form 
of the sexual branches as well as that of the vegetative shoots in this species 
is readily affected by environmental conditions. 
The most fruitful source of material (that near Lake Waubesa) was 
discovered August 11, 1921, when the plants bore mature sex organs in 
