1907] HOLM—RUBIACEAE 179 
G. TRIFLORUM 
The seeds of this species germinate very early, and seedlings may 
be found in wooded ravines in February. The hypocotyl (fig. 28, /) 
is very long and lies on the ground; the primary root is distinct and 
amply branched. Very characteristic are the large blades of the 
cotyledons and the relatively short petioles. Small shoots are already 
developed in the axils of these, while the primary axis, which is erect, 
shows long, glabrous internodes. During the first season the plant 
thus develops three aerial shoots, which however die down to the 
ground in the fall. The hypocotyl and the primary root do not 
persist, but the base of the two axillary shoots from the cotyledons 
remains alive, and the future growth of the individual is secured by 
small buds in the axils of the basal leaves and some secondary roots 
that winter over. In mature specimens the root system is thus repre- 
sented by secondary roots, and the subterranean stem is a pseudo- 
rhizome like that of the preceding species. 
The roots.—The secondary roots are very long and relatively thick 
and strong; they become glabrous very soon. No exodermis is 
developed, and the cortex, which is very compact, consists of four 
starch-bearing layers. The endodermis and the continuous peri- 
cambium are thin-walled, and the stele shows three leptome strands 
alternating with three rays of hadrome; while the center is occupied 
by a thick-walled conjunctive tissue. It appears as if the increase 
in thickness does not commence until during the winter, when the 
epidermis and the cortex become thrown off. 
The lateral roots are capillary and almost destitute of hairs; there 
is no exodermis and the structure is identical with that of the mother 
Toot, but they do not increase in thickness. I observed no case 
where these lateral roots remained enclosed within the cortex, as in 
the former species. 
The stem.—The internodes are quadrangular and sharply four- 
winged; unicellular, pointed hairs are common along the wings, ren- 
dering them quite scabrous. The thin cuticle shows longitudinal 
ridges, and the outer cell wall of the epidermis is slightly thickened. 
Broad groups of thick-walled collenchyma are noticeable in the wings, 
but otherwise the stem has no mechanical support. The cortex con- 
sists of about ten layers in the wings, and of three between them; 
