Diversity: Mostly herbs in temperate floras with a few shrubs and, in the tropics, some trees - a large and important family of about 450 genera and 6, 500 species.  This families is the source of coffee (Coffea arabica - northern Africa), the anti-malarial quinine (Cinchona officinalis - Andean South America), and a red natural dye taken from the 'madder' plant - Rubia tinctorium.

Distribution:  Worldwide with maximum diversity in the tropics. We have 19 genera and 53 species in Texas, including four endemic species of Hedyotis from the southern and western parts of the state.

Floral structure:

Significant features:  This is one of the few flowering plant families that carries the following set of key characters:

Number of androperianth parts varies between four and five, depending on the genus and - with the exception of epigyny - the floral structure is typical of the Asteridae.  While rare, some taxa produce zygomorphic corollas.  Stipules, usually present between the petioles of the opposite leaves and the whorled phyllotaxy of some taxa is believed to be a result of enlargment of the stipules to a leaf-like structure.  Fruit structure is variable, but often baccate or drupaceous.  A coffee 'bean' is actually a 'half-pyrene' in that the Coffea fruit is a 2-seeded drupe.
 
 

Coffea arabica - (left) with versatile anthers and strange drupe-like fruit and Rubia tinctorium (right) - with whorled leaves

Morinda citrifolia from Hawaii - full diversity of the family is expressed in tropical taxa.  This one shows large interpetiolar stipules, a pentamerous corolla and fusion of ovaries from separate flowers to produce a multiple fruiting structure. See the family overview from the University of Hawaii for more examples.
 

More information on the Rubiaceae