venice mallow
Hibiscus trionum                                     

Identifying Characteristics:

Seed:  kidney-shaped, dark brown to black, rough

Seedling:  cotyledons round or heart-shaped with pubescent petiole; leaves alternate, dull green, irregularly shaped

Mature Plant:  fibrous roots from shallow taproot; erect stem, spreading or branching from base; alternate leaves, palmately lobed, margins coarsely toothed, long petiole; 5 petal inflorescence, yellow or whitish, purple petal spot, capsule fruit, round, pubescent, enclosed by membranous sepals

Method of Propagation: seed

Life Cycle: annual herb

References: 
Bryson, Charles T. & Michael S DeFelice. "Weeds of the South."