THE ANATOMY OF THE NODE IN ANGIOSPERMS 
it is relatively primitive in constitution, for it is among primitive types 
that any structure is apt to be found in its most plastic and variable 
condition. 
Rhoedales 
In this order the Papaveraceae seem to be invariably trilacunar, 
but it is noteworthy that the three bundles, at least in the smaller 
portions of the stem, come off very close together. The Capparidaceae 
are entirely unilacunar. The Cruciferae, as we have noted above, 
are both trilacunar and unilacunar {figs. 13 and 14), and from the 
number of intermediate conditions observable, this family furnishes 
one of the best examples of the way in which one type has been de- 
rived from the other. The Resedaceae are unilacunar. 
In this order, therefore, the primitive condition was apparently 
one with three gaps and traces (since it occurs in the most generalized 
and primitive family, the Papaveraceae) and the whole tendency in the 
evolution of the group seems to have been toward the approximation 
and fusion of the various bundles constituting the foliar supply. 
ROSALES 
Plants belonging to this order possess a nodal structure which is 
almost invariably trilacunar {figs. 15 and 17). Some of the more 
important exceptions observed were the following: — Schizophragma, 
Astilbe and a few species of Hydrangea, among the Saxifragaceae, 
have five or seven bundles and gaps; Spiraea, {fig. 16), Exochorda and 
their immediate allies among the Rosaceae are unilacunar and Poten- 
tilla palustris is multilacunar; among the Crassulaceae, all species of 
Sedum and Crassula investigated were unilacunar, but in Cotyledon 
there were in addition to the central bundle two small lateral ones; 
Eucommia is unilacunar; Platanus has seven bundles and gaps, and 
Phaseolus, Dolichos, Gymnocladus and a few other genera of the 
Leguminosae possess a foliar supply of five bundles. Evidence from 
the node, therefore, indicates that the Rosales are a good natural order. 
Geraniales 
The Geraniales resemble the Rosales in possessing, for the most 
part, a trilacunar nodal structure. This characterizes without ex- 
ception all the members of the Geraniaceae, Tropaeolaceae, Oxalida- 
ceae, Linaceae and Rutaceae which were observed. The Simarubaceae 
