722 Thomas . — Seedling Anatomy of 
cotyledon strands. The hypocotyl presents four protoxylem groups with 
or without tangentially developed metaxylem wings, according to age. 
Alternating with the four protoxylem groups are four extended phloem 
masses, which in the upper part of the hypocotyl are twin groups. At the 
node the usual triad of xylem and two phloem groups pass out to form 
the double bundle of the cotyledon. In Primus amygdalus , P. amara , 
P. persica (see Text-fig. 38), and P. spinosa , the intercotyledonary strands 
are continued upwards as the independent lateral bundles of the cotyledons 
(see PI. L, Fig. 11 of Magnolia), but in P. Cerasus these are continuous with 
the flanks of the double bundle (see PL LI, Fig. 23 of Althaea). 
Text-fig. 38. Primus persica. A, cotyledonary node ; b, hypocotyl ; c, root, enlarged, cot, 
intercot = protoxylem in cotyledonary and intercotyledonary planes, respectively. 
Rosoideae. 
Rosa rubiginosa and R. polyantha . The transition in these forms is of 
the simple diarch type. The insertion of the cotyledons at the node is 
slightly asymmetrical, being delayed on the side of the production of the 
first leaf. This asymmetry is reflected in that of the hypocotyledonary 
stele, which shows vascular elements continuous with those of the first leaf 
on one side of the emerging diarch plate. Complete root structure is 
present a short distance below the node, as in the members of the Rhoeadales 
and Ranunculaceae. 
Rubus vestitus and R. xanthocarpus. The two species of Rubiis 
examined show the usual formation of a diarch plate, with rather low 
insertion of plumular traces. The diarch plate has a characteristic form, 
being lignified in two bowed lines connected by the protoxylem groups. 
Lower down in the older seedlings the centre lignifies, so that the stele 
presents a curious protostelic xylem body, upon the periphery of which the 
two small protoxylem groups are scarcely visible. One individual of 
R. vestitus possessed intercotyledonary strands in the upper part of the 
hypocotyl which were continued into the cotyledons as single strands, one 
passing into the left side of one cotyledon, and the other into the right side 
of the opposite cotyledon. That is to say, each cotyledon has, in addition 
