BOTANICAL MUSEUM LEAFLETS 
HARVARD UNIVERSITY 
Cambridge, Ma 
7, No. 10 
THE FOSSIL FLORA OF IOWA COAL BALLS 
II. The Fructification of Botryopteris 
BY 
William C. Darrah 
Botryopteris is a genus of primitive ferns belonging 
to the extinct class or order known as the Coenopteridales 
(5,6). Nearly a dozen species have been described but 
all except the genotype (15) are very imperfectly known. 
The described species are restricted to the Carboniferous 
rocks of France (4), England, Scotland (18), Germany 
(8), Belgium (13), Holland (12) and Illinois (9,11). 
Among the most abundant plants present in the coal 
balls from Dallas County, Iowa, are many petioles ref¬ 
erable to three species of Botryopteris, one of which bears 
a large globose mass of sporangia. Seven specimens of 
this fructification have been collected in the Shuler Mine, 
and an additional specimen in the Urbandale Mine (7). 
Botryopteris forensis Renault (15), the type of the 
genus, is the only species known from the fructification, 
the petiole, and presumably the leaf. All other members 
of the genus are known only from petrified petioles. The 
shape of the xylem of the stele, as viewed in transverse 
section, is the chief generic character (2,4). The petioles, 
which are circular in section, have a broad cortex, and 
