464, MR. E. A. NEWELL ARBER ON THE 
These are separated by the characters of the leaves, inflores- 
cences, and flowers, as well as by the habit. The subgenus 
Caprifolium, which includes the two British climbing Honey- 
suckles, LZ. Caprifolium, L., and ZL. Periclymenum, L., is easily 
distinguished from the two other groups by the compound inflores- 
cence, formed of closely compressed 3-flowered dichasia. No 
synanthy occurs in this group. In the two other subgenera, the 
inflorescence consists of a simple 2-flowered dichasium, in which 
the terminal flower is suppressed. The Nintooa group includes 
climbing shrubs, and, so far as is known, synanthy does not 
occur in any of its species. 
The third subgenus, Xylostewm, is distinguished by the fact 
that none of its members are climbers. Usually the habit is that 
of an erect shrub. In many of the species included in this 
group, synanthy occurs between the two flowers of the cyme or 
the two fruits. This group is by far the largest, containing 
upwards of 70 species *. The great majority of these belong to 
Eastern Asia, occurring especially in China, the Himalayas, and 
in other parts of India. A few species belong to North America. 
Several are European, occurring especially as alpines in the 
mountains of Southern and Eastern Europe. A single repre- 
sentative of the group, L. Xylosteum, L., is a naturalized or 
possibly indigenous British plant. 
The union of the flowers and fruits in certain species of Loni- 
cera is well known, and has for many years been used as a 
character of systematic importance. The main facts relating to 
the morphology of the flowers and fruits have also been described 
by various authors, and may be found scattered throughout the 
systematic literature dealing with this group. At the same time, 
so far as I am aware, no one has yet undertaken a comparative 
morphological study of the synanthy in this genus. As little 
attention appears to have been paid recently to this subject, a 
comprehensive study of the Xylosteum section, from the point of 
view of the synanthy, may be of interest as a contribution to 
the morphology of floral structures. 
The work has been carried out on the following lines :— 
Examination of the various stages in the flowers and fruits has 
been made in the case of a number of species of which material 
could be obtained. In this way I have worked out, independently 
* Fritsch (1891), p. 166. 
