CEANOTHUS IN IOWA 
231 
of the western part of our country and northern Mexico. In 
Iowa two species and a variety have been recognized. Like all 
other members of the genus these forms are very variable, and 
in consequence there is much confusion in the descriptions, and 
in the definition and recognition of specieis. A discussion of these 
differences and variations, so far as they concern the Iowa species, 
is here presented. 
The three forms found in Iowa are: Ceanothus americanus L., 
C. ovatus Desf., and C. ovatus pubescens T. & G. 
I. Ceanothus americanus L. PI. VIII, fig. 1, a to i ; 1 to p. 
This is the larger species, once common on the prairies, especial- 
ly in the eastern part of the state, but now most commonly pre- 
served in dry, open woods and oak openings. This species is 
variable both in form and structure of some of its parts and in 
habit, but it may usually be readily recognized by its broad, soft, 
often subcordate leaves, the elongated stalk of the flower cluster, 
the usually clustered stems, and the larger, lighter-colored smooth 
seeds. The flower cluster is also usually more elongated than in 
the following species, and the flowers appear later. 
A comparison of published descriptions and observations on 
our Iowa material shows that practically the entire range of vari- 
ation in this species is exhibited in the Iowa representatives. The 
leaf is the most variable part of the plant and a more detailed 
discussion of its characters is worth while. 
Form. — The form of the leaf is variously described in the 
books as ovate ^ ; ovate or oblong-ovate ; 
oblong-ovate ; obovate or oblong-ovate ; heart-ovated ; 
and ovate or ovate-lanceolate, rarely orbicular ovate 
The most common Iowa forms vary from oblong, through ob- 
long-ovate to ovate, but the larger leaves on most plants are often 
cordate-ovate or even cordate. Occasionally the leaves, especially 
the later ones, are narrowly oblong or ovate-lanceolate, and still 
less frequently broadly oval or nearly orbicular leaves occur. 
Base. — The base of the leaf has been described as rounded 
or rarely acutish, or sometimes a little cordate ; abruptly nar- 
rowed or subcordate ; sometimes unequal or slightly cordate ; 
obtuse or subcordate ; often slightly heart-shaped ; and 
acute or sometimes slightly cordate 
The Iowa specimens show much variation in the form of the 
base, often on the same plant. They are rather rarely narrowly 
acute at base, but more frequently vary from broadly or abruptly 
