Taxonomy of Flowering Plants - LECTURE NOTES - Spring, 1998
Hugh D. Wilson - rm. 306, Butler Hall
23 March 1998
The Rosidae
Family Overview - The Fabales

Mimosaceae - the Mimosa Family

Diversity:  The Mimosaceae includes about 40 genera with ca. 2,000 species, both herbaceous and - mostly - woody.

Distribution:  Worldwide, but mostly tropical and subtropical with a focus on dry regions, as indicated by the large and typical Genus Acacia.  We have 10 genera and 54 species in Texas including the 'mimosa tree' (Albizia) that grows on campus and sometimes escapes cultivation, mesquite (Prosopis), plus 'sensitive' herbs (leaves move when touched) of the genera Mimosa and Schrankia.

Floral structure:

 
 Significant features:  Leaves of this family tend to be bipinnately compound.  While the actinomorphic flowers are distinctive relative to other beans, they are usually quite small.  The most distinctive floral feature of the Mimosaceae is the inflorescence, which is usually a spherical head of these small, regular flowers with the stamens well excerted from the (often) sympetalous corolla and the filaments taking on an attractive function.
 

 Local Acacia smallii; plant, inflorescences, and fruits - note bipinnate leaves:
 
 
 
 
  Local herbs of the Mimosaceae:   Neptunia lutea (right) and Mimosa nuttallii (left) 
 
 
The local mesquite (Prosopis glandulosa - below) shows bipinnate leaves but only 1 or rarely two pairs of pinna (compounded leaflets) - and a linear (non-spherical) inflorescence - this species, according to Correll and Johnston is "probably the commonest 'legume' in Texas" and, given habitat destruction in the state and concurrent invasive advance of this species from the South, this statement is supported as time passes.
 
branch
leaves
flowers
fruits
 
 More information on the Mimosaceae
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