Distribution:  World wide, especially xeric or saline habitats with centers of diversity in South America and Australia.  The Texas flora includes 16 genera and 60 species, many of these common weeds of agricultural fields.

Floral structure:

Significant features:  A difficult family in that the flowers are small and the plants more or less 'streamlined' with few conspicuous characters.  Elements of the family are, however, often common and ecologically important.  Field recognition keys on an 'eye' focused on reduced flowers, often perfect but sometimes unisexual, producing the distinctive, often uniovulate 'beaked' fruit depicted below and a 'fleshy' or succulent aspect to the plant.  Epigyny is rare in the family (only Beta).

  Overview - Beta vulgaris - from Dr. Otto Wilhelm Thomé, Flora von Deutschland Österreich und der Schweiz

Chenopodium berlandieri with sectioned fruit (left - pericarp, testa, perisperm, embryo), whole fruit (center - reticulate pericarp, darker testa, and 'beak' of the radical), and (right)flower at anthesis:
 
 

  Chenopodium  missouriense  - inflorescence - at anthesis
 

The Amaranthaceae (pigweed family) is a 'sister' group to the Chenopodiaceae in that all working with classification of the Caryophyllales, regardless of approach, agree that the two families are closely related.  They also share similarities in size, structure, ecological amplitude, and distribution.  Check your text, or information available on the network, to determine how one might distinguish between these two families if only the flower was available for inspection.

More information on the Chenopodiaceae, including species diversity in North America