222 
H. F. Wernham. 
within the family, and roughly 22%' of the total number of species 
are herbs. 
In regard to the general principle of adaptation to insect-visits, 
the Rubiacese are decidedly primitive in comparison with the groups 
with which we dealt in the preceding chapter. Setting aside the 
rare and isolated cases of zygomorphy referred to above, this 
adaptation is practically confined to the attainment of conspicuousness 
either by enlargement of the individual flower, or by aggregation 
into dense inflorescences. In the former case conspicuousness is 
frequently coupled with considerable elongation of the corolla-tube, 
the length of which is sometimes enormous,— Posoqueria, Hillia, 
Cosmibuena, Randia spp., Gardenia spp., etc. 
Conspicuousness by virtue of aggregation is reflected primarily 
in the umbellate or corymbose inflorescence, which is, broadly 
speaking, characteristic of Rubiaceae, especially of those members 
of the family which are to be regarded as most nearly representative 
of what we shall name the rubialian stock ( infra ); simply spicate or 
racemose inflorescences are quite exceptional. The aggregation 
displays every conceivable degree of density ; the limit is attained 
on the one hand in the capitula, often involucrate, of genera such as 
Uragoga (Cephaelis), Schradera, Sperniacoce spp., etc., and especially 
in the globose heads of the tribe Nauclece ; and on the other hand 
in the close axillary clusters seen, e.g., in many of the tribe Sperma- 
coceae, which sometimes recall the verticillasters of Labiatae. In 
some cases the calyces fuse together and lose their separate identity 
in the fruit,— e.g., many Nauclece, Morinda, etc. This aggregation, 
however dense, never involves in Rubiaceae the zygomorphy of the 
outer florets; the latter we shall meet with in more advanced members 
of the rubialian plexus. 
A special form of conspicuousness occurs among Rubiaceae with 
sufficient frequency to be regarded as the expression of a tendency, 
—the foliaceous development of one or more of the calyx-lobes 
(calycophylly ). This phenomenon is met with in various genera of 
diverse affinity, in all or some only of the species: the most familiar 
example is Mussaenda, several species of which—notably M. frondosa 
—are cultivated as ornamental plants. Inequality of the relatively 
large calyx-lobes is a common feature in Rubiaceae. 
In the number of carpellary leaves composing the pistil the 
range varies from isomery with the corolla to two, variation occurring 
sometimes within the limits of a single genus ( Gonzalea , Sabicea, 
1 Including Galieae, which represent about 10% (infra). 
