Rubiales. 
22 t 
Henviquezia the corolla is bilabiate, recalling that of many Bignoni- 
aceae; this includes about five species only. In other cases the corolla- 
tube is bent,—e.g., Hippotis, Dichilanthe, Chasalia ; in others, e.g., 
Palicouvea, the tube is furnished with a small sac or spur at the base. 
In all these cases, however, the androecium is isomerous with the 
corolla, although a condition comparable with didynamy—in effect, 
at any rate—is observable in the insertion of the stamens at different 
levels (see figures of Henviquezia, p. 40, and Aitchisonia, p. 126, of 
Engler, Nat. Pflanz. IV, 4). The exceptions to the isostemonous 
arrangement are extremely rare, and it is open to doubt whether 
the relative examples are properly classed with Rubiaceae. Such 
are Cavlemannia (3 spp.) and Silvianthus (1 sp.), which differ further 
from other Rubiaceae in having leaves with toothed margins and 
reduced or obsolete stipules. In the monotypic Pvaravinia from 
Borneo the flowers are dioecious, and the male flowers are described 
as having twice as many stamens as corolla-lobes. 
The character-diversity in Rubiaceae is seen in 1st, the habit; 
2nd, the modes of attainment of conspicuousness of the flower or 
inflorescence; 3rd, the number of carpels and loculi in the ovary; 
and 4th, in the number of ovules contained in each loculus. This 
constitutes a wide field of variability as compared with any family 
which we have considered previously, and we are led to the pvima 
facie conclusion that Rubiaceae may represent a relatively primitive 
group. In the first place the habit is as a rule arboreal or 
fruticose; and we have already seen in more than one connection 
that this character is suggestive of relative primitiveness, among 
the higher Sympetalae at any rate. Herbs, however, are not 
uncommon, although the herbaceous forms are confined for the 
most part to certain tribes, viz., —Oldenlandiese, Knoxieae, Sperma- 
coceae, and Galieae. In the Anthospermese, the transition from the 
shrubby to the herbaceous condition is well illustrated in the series 
of genera ; some Spermacoceae are suffrutescent, and Oldenlandieae 
are linked with neighbouring tribes by not a few shrubby forms. 
Herbaceous genera of undoubted affinity, again, occur in tribes 
composed typically of arboreal and fruticose genera; such are 
Sipanea and Limnosipanea in Rondeletieae; Bouvavdia (shrubs and 
herbs) in Cinchoneae; Coccocypselum and Sabicea spp. in Mussaendeae; 
Geophila, Uvagoga (shrubby to herbaceous), and Fevgusonia in 
Psychotrieae. 
A distinct tendency to the herbaceous habit is thus traceable 
