Rubiaceae.
The Coffee family has around 620 genera (450 – 650) with up to 13,150 species.
It is the 4th largest flowering plant family.
Australia has about 42 (36 – 45) genera and 200 species.
It is divided into subfamilies – usually three:
Cinchonoideae with 1704 species,
Ixoroideae with 4026 species and
Rubioideae with 7670 species.
Some of the better known species include Atractocarpus, Bouvardia, Burchellia, Coffee, Coprosma,
Gardenia, Ixora, Mussaenda, Pavetta, Pentas, Psychotria, Randia, Rondeletia and Serissa.
Most are shrubs but there are also trees and some lianas and herbs.
The often angular stems may be smooth or hairy.
The simple leaves are mostly opposite and decussate (alternate pairs at right angles).
Rarely they may appear to be whorled or alternate.
They may have stalks or the blade may be directly attached.
The blades are usually elliptic with a pointed tip.
The edge is smooth or toothed and the blade many have tufts of hairs or pits.
There are stipules that are mostly interpetiolar (between the petioles).
They can be free or fused and narrow or leaf-like.
They often have a row of glands (colleters not collectors) on the inner surface.
The glands produce mucilage that protects the developing leaf bud.
When the leaves are larger the stipules commonly fall off leaving a scar.
Terminal or axillary inflorescences typically consist of a number of flowers, rarely just one.
They take various forms from a branched structure to a globose head.
Typically the terminal flower blooms first so the inflorescence does not continue to grow.
Flowers are mostly bisexual with parts in 4’s or 5’s and an inferior ovary.
They may or may not be on stalks and bracts may be present.
Flowers are usually small to medium in size and are mostly radially symmetric.
There are commonly 4 or 5 sepals (3 – 6, rudimentary or absent).
They are mostly fully or partially fused with no lobes or blunt or toothed ones.
One or more lobe may be enlarged and coloured.
There are mostly 4 – 5 petals (3 – 10) in one whorl with the bases fused.
The corolla is typically funnel-shaped or tubular.
The lobes are usually similar but rarely they form 2 lips.
There are usually hairs in the mouth of the tube.
Many flowers are white or cream with some yellow and rarely red or blue.
There are almost always 4 or 5 stamens (equal to the petals) that alternate with the petals.
They can be inserted into the base or top of the corolla tube or midway along it.
The anthers are mostly free but can be attached to each other.
They open inwards via longitudinal slits or occasionally by apical pores.
The ovary is almost always inferior but occasionally semi-inferior or superior.
Derived from 2 carpels (1 – 9) it has 1 or 2 locules with 1 to many ovules.
Placentation is almost always axile.
The style can be single with a simple or bilobed stigma with or without papillae.
There may also be 2 or 5 styles that are separate or partially joined.
Styles can be long or short.
There is often a nectiferous disc at the top of the ovary.
The fruit can take many forms – a berry, capsule, drupe, a schizocarp (from flowers with more
than 1 carpel each with a single ovule) or a compound fruit (many fruit fused together).
The main features are:
simple, opposite and often decussate leaves,
interpetiolar stipules with glands,
inflorescences with the terminal flower opening first,
inferior ovary and a nectiferous disc.
J.F.
