The Dilleniidae
Family Overview - The Primulales
Primulaceae - the Primrose Family

Diversity:  30 genera and about 1,000 species of mostly perennial herbs with a few suffrutescent taxa.

Distribution:  Centered in cool, north-temperate parts of the World with some extension southward at high elevations.  We have seven genera in Texas with 12 species.

Floral structure:

Significant features:  This family demonstrates a suite of floral features that, relative to other elements of the Dilleniidae, are advanced, specialized, or derived.  Floral appendages on all four whorls are reduced to a relatively small number, in this case 5, i.e., the primulaceous flower is fully pentamerous. Also, with the exception of the androecium, all whorls show connation.  The family also falls into two convenient 'subsets' of key characters.  All (or at least most) taxa show either opposite, whorled, or (in many cases) basal leaves and the gynoecium shows free central placentation, a very unusual condition found, among those covered in this course, in only one other family.  A distinct feature of this family, relative to sympetalous elements of the Asteridae with which it might be confused, is the placement of the 5 stamens opposite the petals (each stamen is directly in front of a corolla lobe as opposed to being positioned between the lobes at the sinuses).

  

anagallisThe California flora includes 9 genera and about 22 species of the Primulaceae and an overview of floral variation is available from the California Flora Photos website.  This opens with photos of the Scarlet Pimpernel (Anagallis arvensis) that has blue flowers.  While corolla color of this introduced (from northern Europe) weed is normally, as indicated by the local name, scarlet to salmon, plants producing blue flowers are not uncommon in either California or Texas.  The difference between blue and reddish corolla pigmention has a relatively simple genetic foundation and, as a result, the blue form of Anagallis arvensis is  sometimes not recogized as a formal element of the classification system or often treated at the lowest level - forma, i.e., A. arvensis L. f. caerulea (Schreb.) Baumg.

As the name indicates, the plant was first named by Linnaeus and the parenthetical authority points to some history with regard to the 'caerulea' name that has involved 'Schred.' and 'Baumg.'  The Harvard University Herbarium provides an Authors Database online that allows entry of the abbreviated name as a query to determine the full author's name and other info.  This indicates that:

Schred. = Johann Christian Daniel von Schreber (1739 - 1810)
Baumg. = Johann Christian Gottlob Baumgarten  (1765-1845)

More information on the Primulaceae

Return to the Biology 301 homepage or the Dilleniidae page