The Dilleniidae
Family Overview - The Ericales
Ericaceae - the Heath or Blueberry Family

Diversity:  A family about 125 genera and over 3,500 species, although estimates of family diversity vary greatly.  Mostly woody shrubs, rarely herbs or small trees.  Our most conspicuous local representative, Vaccinium arboreum, represents the rare exception.  Diversity tends to increase in areas characterized by an acidic or low pH environment such as bogs, swamps, moors or heathlands, and deep forests. Vaccinium species producing blueberries on a commercial scale (several species) and cranberries (V. macrocarpon)  been little changed - from the wild type - via human selection.

Distribution:  Throughout temperate parts of the World with extensions into the tropics at higher elevations, 6 genera with 15 species in Texas.  Adaptation of this family to occupy acid soils is, in part, related to their symbiotic association, via mycorrhizal root connections, with fungi.

Floral structure:

Significant features:  Many genera show sympetaly and a distinctive urn-shaped (urceolate) corolla.The '2x' androecium (stamens twice the number of petals or corolla lobes) is also useful, as is the tendency for poricidal anther dehiscence, (many genera), extensions or appendages from the anthers, and release of the microgametophytes as tetrads or units of 4 pollen grains. The ovary matures to - usually - form a berry or capsule.  Epigyny is restricted to the typical subfamily (Vaccinioideae) and circumscription of the family can be either broad (to include the Monotropaceae and Pyrolaceae as subfamilies, see this overview and the Thorne treatment) or narrow to exclude these taxa, which are then treated as distinct families.
 
 
 

Urceolate corollas of Vaccinium (left) and Pieris (right)

 
 
 
Flower cross section of Arbutus menziesii (left) showing urceolate corolla and appendaged anthers and inflorescence of Gaultheria shallon (Botany - University of Hawaii)

More information on the Ericaceae


Return to the Biology 301 homepage or the Dilleniidae page