1924] 
GRANT—A MONOGRAPH OF THE GENUS MIMULUS 115 
Botanical Garden. It is an interesting and instructive plant, 
because although shrubby, with the glutinous exudation and 
separated placentae of Diplacus, it has equal acute calyx-teeth 
that suggest Ewmimulus, a corolla that resembles some of the 
species in Erythranthe, and the type of capsule-dehiscence char- 
acteristic of the subgenus Synplacus. The calyx is peculiar 
inasmuch as it becomes spirally twisted over the mature capsule. 
Diplacus.—The general conception of the genus Diplacus as 
stated by Nuttall and Greene was of shrubs covered with a 
glutinous exudation, having revolute leaf-margins and а pris- 
matic calyx closely investing the linear-oblong capsule, the latter 
splitting down the inner suture, rupturing the calyx, and showing 
large divided placentae attached to the valves. Herbarium and 
field work demonstrate that the revolute character of the leaves 
is a variable one, some species having practically all revolute 
leaves and others having few or none at all. Furthermore, there 
is a tendency toward leaves of this kind in some of the species in 
the (пов and Eunanus sections. The dehiscence of the capsule, 
rupturing the closely invested calyx, was regarded as a good 
generic character until the same thing was found in M. Kelloggii, 
à species in every other essential belonging to the section noe. 
The divided placentae, on which the genus was originally based, 
is characteristic also of the other sections of Schizoplacus. There- 
fore, the only constant characters left for Diplacus as a genus 
were its shrubbiness and peculiar glutinous exudation. In this 
connection, M. Clevelandii, an endemic Mimulus growing in 
San Diego Co. and Riverside Co., shows the typical glandular- 
villous pubescence of Eunanus although definitely suffrutescent. 
Also M. Treleasei, a newly described species collected by Trelease 
in the state of Puebla, Mexico, though shrubby and having a 
glutinous exudation, is not in most of its other characters related 
to Diplacus. There are then no sufficient characters for main- 
taining Diplacus as a genus. 
PHYLOGENY 
Any discussion of the phylogenetic development of this group, 
as of any group including a large number of closely related 
species, must, of necessity, be more or less hypothetical. Never- 
