Galium aparine, flowers.en.wikipedia.org (Accessed 4/2014).

Galium is a genus of annual or perennial herbs, stems slender, 4-angled. 

Leaves whorled. 

Flowers 4-parted, radially symmetrical, tubular, petal lobes about as long as tube, small, stamens 4, ovary inferior, 2-parted, styles 2 (use lens). 

Fruit dry (ours), 2-parted, each part rounded, 1-seeded.