1907] HOLM—RUBIACEAE 181 
rapidly a beautiful crimson color. The epidermis is glabrous and 
very small-celled; it covers the cortex directly, there being no exo- 
dermis. The cortex is thin-walled, but compact; no starch was 
observed, but globules of resin occur in some of the cells; it consists 
of about six strata, the innermost of which is differentiated as a small- 
celled, thin-walled endodermis. Secondary formations have changed 
the primitive structure of the stele, which shows a confluent zone of 
leptome and many rows of vessels separated by a few strata of thick- 
walled conjunctive tissue, which extend to the center. 
The lateral roots are also glabrous and have no exodermis. About 
four layers of cortex with raphides border on a thin-walled endoder- 
mis. The pericambium is continuous and surrounds four broad 
groups of leptome alternating with four short rays of hadrome, with 
a central group of thick-walled conjunctive tissue. A lateral root of 
the second order (borne upon the former) is exceedingly thin and 
slightly hairy. In this the cortex consists only of two layers, the 
innermost of which is large-celled, with the cells stretched radially 
and containing raphides. The stele is diarch. 
The stem.—The structure of the stolons is rather weak; the epi- 
dermis and the primary cortex had been thrown off, and the central 
cylinder was merely covered by some layers of cork. This cork was 
evidently developed from endodermis, as in other species of the genus 
and of Rubia, as stated by SOLEREDER (p. 510). The stele is located 
directly inside the cork and consists of a confluent zone of leptome 
separated from the hadrome by strata of cambium. A small pith 
occupies the center of the internode. 
The aerial stem is sharply four-winged, covered by a thin cuticle, 
which is somewhat wrinkled along the wings, but otherwise smooth. 
The epidermis is glabrous and the outer cell wall thickened, especially 
in the wings. Several strata of heavily thickened collenchyma were 
observed beneath epidermis in the wings (fig. 34, coll). The cortical 
parenchyma in the wings consists of about seven compact layers with 
chlorophyll, and of only three between them. The endodermis is 
thin-walled and surrounds the stele, which shows the same structure 
as in the preceding species. 
The leaves.—The lateral cell walls of the epidermis are prominently 
undulate on both faces, when viewed en jace. Cells with resin are 
