FORM  Small annual or perennial herbs. May be prostrate.

Genera    19           

Species 350 in our area 13 (Gray);  13 (B&B)⁴³

Distribution   North and South America

Flowers Perfect Solitary or in clusters

#Parts  2 Sepals, 4-6 petals, 4-6 stamens    

Symmetry regular

Leaves entire, usually opposite