_The leaves are always opposite or verticillate. The flower is
epigynous_, ☿, 5-(or 4-) merous, with the usual sympetalous diagram;
2–5 carpels. The inflorescences are frequently dichasial. The sepals
are small, reduced to teeth, and become almost entirely suppressed
in the higher forms.--The flower is regular in _Rubiaceæ_ and some
_Caprifoliaceæ_, but in other genera of this latter order (especially
of _Lonicereæ_) it is unsymmetrical. In several genera of the order
first mentioned the loculi of the ovary contain many ovules, but in
the last the number of loculi and ovules becomes reduced. This is to
some extent connected with the nature of the fruit which is many-seeded
in most instances, namely a capsule or berry, but in others nut-like.
Endosperm is present.
The family on one side is allied to the Contortæ (not only
through the _Loganiaceæ_ but also through the _Apocynaceæ_), and
may be regarded as an epigynous continuation of this family; on
the other side it is allied to the Valerianaceæ and Dipsacaceæ.
Many points of agreement with the _Cornaceæ_ and _Araliaceæ_ are
also found, and in fact several Caprifoliaceæ are distinguished
from these by hardly any other feature than the gamopetalous
corolla.
[Illustration: FIG. 584.--_Cinchona calisaya._ Flowering branch.]
Order 1. =Rubiaceæ.= Leaves opposite (or verticillate), undivided and
entire, with _interpetiolar stipules_ (Fig. 586). Flowers epigynous
and hermaphrodite, _regular_, 4- or 5-merous with the usual arrangement
(Figs. 585, 588–590); corolla gamopetalous, in æstivation often
valvate; ovary _frequently 2-locular_.
[Illustration: FIG. 585.--_Cinchona calisaya._ _A_ entire flower;
_B_ after removal of the corolla; _C_ longitudinal section of
ovary; _D_ fruit; _E_ seed.]
There are no external characters which at once distinguish
this exceedingly large order, as in many other natural orders
(Compositæ, Umbelliferæ, etc.), but the _opposite_ leaves with
_interpetiolar stipules_ form an excellent mark of recognition.
It is divided into many sub-orders and groups, especially
characterised by the nature of the ovary (1 or several ovules
in each loculus), and of the fruit (schizocarp, berry, drupe,
capsule).--The corolla is bilabiate in 4 genera; its æstivation
in some is twisted; in _Capirona_, etc., the filaments are of
unequal size. The ovary is semi-epigynous in _Henriquezia_, etc.
In _Morinda_ all the fleshy fruits coalesce into one multiple
fruit.
=1.= CINCHONEÆ. The fruit is a 2-valved _capsule_, with many winged
seeds (Fig. 585). _Cinchona_ (Quinine, Fig. 584). Trees and shrubs
with the foliage and inflorescence somewhat resembling _Syringa_;
the corolla also being of a lilac colour, more or less salver- or
funnel-shaped, and frequently edged with a fringe of hairs (Fig. 585),
is somewhat similar to that of _Menyanthes_. Their home is the Andes
from Bolivia to Venezuela, varying in altitude from 1–3000 metres.
There are now large plantations in Java and E. India. ~(The name
“quinine” is of Indian origin; that of the genus “_Cinchona_,” is from
the Spanish Duchess Cinchon, who in 1638 first introduced the bark into
Europe.) The following are closely allied: _Cascarilla_, _Remijia_,
_Ladenbergia_, _Manettia_, _Bouvardia_, etc.~
=2.= GARDENIEÆ. Trees and shrubs, frequently having a many-locular
berry. _Randia_, _Gardenia_, _Genipa_, _Hamelia_, etc.
=3.= COFFEEÆ. Only 1 seed in each of the two loculi of the ovary;
_the fruit is a drupe with 2 stones_. _Coffea_ has an ellipsoidal
fruit about the size and colour of a cherry; the two thin-shelled,
parchment-like stones are enclosed by a thin layer of pulp; the two
seeds are flat on the side turned to one another, which has also a
deep, longitudinal groove curving to the sides. The endosperm is hard,
horny and greyish (without starch); the small embryo lies in the lower
end near the circumference. The Coffee-plant (_C. arabica_) is a small
tree, or more frequently, and especially in plantations, a shrub with
large dark-green leaves and scented, white flowers. Its home is in
Tropical Africa; it is now cultivated in many tropical countries.
_C. liberica_, W. Africa.--_Cephaëlis_ (_C. ipecacuanha_, Fig. 586;
the roots are officinal).--~_Psychotria_, _Chiococca_, _Ixora_,
_Hydnophytum_, _Myrmecodia_, etc.~
[Illustration: FIG. 586.--_Cephaëlis ipecacuanha._ Portion of a
branch: _st_ stipules.]
=4.= SPERMACOCEÆ. Chiefly small shrubs and herbs, many of which
are weeds in tropical countries. The stipular sheaths bear
numerous bristles at the edge. _Spermacoce_, _Borreria_, _Diodia_,
_Richardsonia_, etc.
=5.= STELLATÆ. _Herbaceous plants with_ verticillate leaves (Figs.
587, 588–590); _the stipules are large, leaf-like_, and resemble the
lamina of the leaves, so that _the leaves appear to be placed several
in a whorl_, while in reality there are only two opposite leaves, the
stipules of which project _freely_, and are not erect (Fig. 587).
[Illustration: FIG. 587.--_Rubia tinctorum._]
In some cases there are apparently 4 leaves in the whorl, and then 2 of
these are leaves, and the other two are their interpetiolar stipules.
When there are apparently 6 leaves, then the two of these which are
opposite each other are leaves, and the other four are stipules;
if there are several members in the whorl, then a division of the
stipules has taken place. The proof of this theory is founded upon
the fact that not more than 2 of the leaves of the whorl ever support
buds (which, in addition, are seldom of equal vigour), and also that
the whorls do not alternate with each other, which, according to the
rules of the position of the leaves, they should do if all the members
of a whorl had equal value. If there are, for instance, 4 members in
two successive whorls, they stand right above one another, and do not
alternate. The development and anatomical relations (the branching of
the vascular bundles) also point to the same conclusion.~--All the
other groups of the order have only 2 small scale-like interpetiolar
stipules, or they form at the base of the leaf-stalks an interpetiolar
sheath, having often a toothed edge (Fig. 586).--Another characteristic
feature in this group is that the calyx is rudimentary, the corolla
_valvate_ (Fig. 588), and that each of the two loculi of the ovary has
only 1 ovule. The fruit is a _schizocarp dividing into 2 fruitlets_
(Fig. 590). ~The forms of the fruit, as well as many other characters,
as, for example, the epigynous flower, the rudimentary calyx, the two
free or almost free styles, present interesting analogous resemblances
to the polypetalous order of the Umbelliferæ.~ This group has its home
chiefly in the temperate regions of the northern hemisphere, especially
about the Mediterranean; it is the only group which occurs in this
country, represented by 4 genera.
[Illustration: FIGS. 588–590.--_Rubia tinctorum._
FIG. 588.--Diagram.
FIG. 589.--Longitudinal section of flower.