This section is from the book "A Manual Of Weeds", by Ada E. Georgia. Also available from Amazon: A Manual Of Weeds.
Native. Perennial. Propagates by seeds and by many-jointed runners which take root at the nodes. Time of bloom: May to September. Seed-time: July to November.
Range: Throughout North America; also in Europe and Asia. Habitat: Wet grasslands, banks of streams, lake and sea shores.
All that this plant seems to require is that the ground shall be damp, and, whether the land be the tropic shores of the Gulf of Mexico or an Alaskan or Greenland marsh, it is satisfied.
The weed springs from a slender taproot, fringed with many thready rootlets. Leaves thickly tufted, spreading, six to eighteen inches long, pinnately compound with seven to twenty-five oblong, tooth-edged leaflets, the larger ones at the tip, decreasing in size inward to the long, grooved petiole, dark green and smooth above but underneath white with fine, silken hairs. Thrust out from among the tufted leaves are a number of jointed runners, one to three feet long, the young plants sitting on the nodes until the parent has pushed them out a convenient distance for striking root and starting an independent growth. Flowers solitary, lifted on slender, erect, axillary peduncles, bright yellow, nearly an inch broad; calyx-lobes acute, silky-hairy; these fold over the seed-heads until the smooth, small achenes have ripened, when they reopen and the nodding stems scatter them abroad.
Good drainage is all that is necessary in order to drive out the Silverweed, but in places where that is impracticable the plants should be closely cut in June, before the first seeds fall or any runners have taken root.