This section is from the book "A Manual Of Weeds", by Ada E. Georgia. Also available from Amazon: A Manual Of Weeds.
Introduced. Annual and winter annual. Propagates by seeds. Time of bloom: June to October. Seed-time: July to November. Range: All over North America except the extreme North. Native of Europe, but widely distributed in Asia, Africa, and Australia. Habitat: Nearly all soils; invades almost all crops.
In fields and along roadsides, and particularly in barnyards, where the soil is enriched with the constant droppings of cattle, this vile weed thrives; for no grazing animal will eat it because of its rank odor and acrid juices. The modern farmer rides his "self binder" through the grain fields and doesn't curse the Mayweeds as did the men who had to "cradle the wheat" and bind it with hand-twisted straw withes, and whose hands, arms, and feet became as though scalded from repeated contact with the acrid, glandular foliage of this weed and from its seedy tops sifting into their shoes as they swung the cradle or the scythe. "The Mayweed doth burn and the Thistle doth fret," wrote Thomas Tusser, sympathizing with his harvesters, nearly four hundred years ago; and there are localities in this country where the words are yet applicable.
Stem six to twenty inches in height, smooth below but glandular and somewhat hairy above, much branched, and spreading. Leaves alternate, sessile, pinnate, twice or thrice divided into linear, acute segments. Heads numerous, solitary, terminal, about an inch broad; rays fifteen to twenty, neutral, white, three-toothed, spreading, becoming reflexed as they wither; disks yellow, hemispheric, growing cone-like with age, the florets tubular and perfect; bracts of the involucre oblong, scarious margined, obtuse, usually somewhat hairy. Achenes oblong, ten-ribbed, roughened with glandular tubercles, and without pappus; they are nearly always found as an impurity in seeds of grass and clover. (Fig. 340.)
Fig. 340.-Mayweed (Anthemis Cotula). X 1/3.
The plant is an annual, and, if it were persistently destroyed before any seed had dropped into the soil to vex another year's crop, it must needs disappear. It would pay even to hand-pull it, but prompt cutting would be sufficient. In grain fields the crop may be relieved of much of the crowding growth of the weed by harrowing out the seedlings in the spring.