Some weeds have a very wide distribution, thriving all around the world in temperate climates, while others are more limited in range; some thrive only in dry, thin, sandy soil and others in wet soils. To some extent the presence of a few weed-seeds is almost as objectionable when once on the farm, as though there were more, because these few may thrive and seed freely.
In many respects the lists of weeds for New Jersey is different from the list in Michigan, while half the weeds of Nevada or Oregon are not known in our state.
Chess, cockle, red root and rye are liable to be troublesome in fields of winter wheat, because the seeds are more or less difficult to separate from this grain and for the reason that they require a portion of two years to come to maturity.
Meadows and pastures, especially where the land is not fertile, abound in weeds that require two years or more to produce seeds, such as narrow-leaved dock, bitter dock, bull thistle, carrot, teasel, two kinds of mulleins, night-flowering catchfly, evening primrose, several kinds of fleabane, ox-eye daisy, orange hawkweed, two or three kinds of plantain, Canada thistle, hound's tongue, stick seed, sow thistle, horse nettle, buttercups, toad flax, silvery cinquefoil, and many more, not excluding some annuals, like crab-grass, tickle grass, pigeon grasses. As crops of corn, potatoes, beans, turnips, beets and squashes are ready to harvest at the close of one growing season they are molested more or less by pigeon grasses, several pigweeds, purslane, crab-grass, barnyard grass, tickle grass and a number of others.
In 1897 some seventy-five lots of timothy seeds were examined and the following list of twenty-four species of weeds were found. Doubtless other weeds may still be found in other lots of timothy seed. No sample was entirely free from weeds. Pepper grass was most common, next followed tumble weed and then shepherd's purse:
- Amaranthus graecizans, Tumble weed.
- Amaranthus retroflexus, Rough pigweed.
- Anthemis Cotula, May weed.
- Brassica arvensis, Charlock. Brassica nigra, Black mustard.
- Bursa Bursa-pastoris, Shepherd's purse.
- Carduus arvensis, Canada thistle.
- Carex straminea. A kind of sedge.
- Chenopodium album, Pigweed.
- Chenopodium filicifolium, Another kind of pigweed.
- Lactuca Canadensis, Wild Lettuce.
- Lepidium Virginicum, Wild Pepper-grass.
- Onagra biennis, Evening primrose.
- Panicum capillare, Hair grass, tickle grass.
- Plantago lanceolata, Narrow-leaved plantain.
- Plantago Rugelii, Rugel's Plantain, one of the broad-leaved plantains.
- Poa compressa, Flat-stemmed poa, wire grass.
- Potentilla Monspeliensis, Rough cinquefoil.
- Prunella vulgaris, Self-heal.
- Rumex Acetocella, Field or sheep sorrel.
- Sisymbrium officinale, Hedge mustard.
- Verbena angustifolia, Narrow-leaved vervain.
- Verbena hastata, Blue vervain.
- Verbena urticifolia, White vervain.
In examining some 130 lots of clover seeds as found in the market during 1897, thirty-two kinds of weed seeds were found. Sheep sorrel was most common, next to this yellow or bitter dock and green foxtail. Only three samples of clover seed was free from weeds, but possibly some weeds might have been seen if larger quantities had been looked over.
During the year 1908, eleven years later, 47 kinds of weed seeds were found in 122 lots of seed of red clover, a gain of nearly 50 per cent.
During three months from January 1, 1910, in examining 450 lots of seeds of grasses, clovers and alfalfas, besides large numbers of common weeds that we know, were 74 kinds not known to the writer. Of these 74 kinds, probably some will never become weeds of any account. Some of these came with alfalfa from Montana and some were importations from Europe and elsewhere.
Parasitic fungi rank as weeds; such as rusts and smuts of wheat, oats, corn; apple scab, black knot of plum, brown rot of cherry, anthracnose of beans.