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The rapid extension of weeds in Michigan
W. J. BEAL.

In volume five of the Michigan Academy of Science, may be found an
approximately correct list of weeds indigenous to Michigan. This list
consists of about thirty-five species only. The same report contains a list
of seventy-eight species of weeds introduced from Europe and Asia.

For use in the laboratory, I have a list of two hundred and six species of
weeds to be found thriving in this state, and I feel sure that if this state was
thoroughly searched, fifty or more additional ones would be found, and where
the limit will eventually be, I dare not predict.

HOW ARE WEEDS INTRODUCED AND HOW ARE THEY SPREAD?
1. By live stock, carried in the hair or fleece or carried by the feet;
in some instances -passing alive with the excrement.
2. By unground feed stuff purchased.
3. By adhering to the insides of sacks where they were placed with
grain.
4. In barnyard manure drawn from town.
5. In the packing of trees, 'crockery, baled hay and straw.
6. By wagons, sleighs, threshing machines.
7. Sometimes by plows, cultivators and harrows.
8. By railway trains passing near a farm.
9. By ballast of boats at wharves.
10. By wool-waste at factories.
11. By birds, squirrels, and mice.
12. By water of brooks, rivers, by washing and by irrigating ditches.
13. By the wind aided by little wings and by drifting on the snow.
14. By dropping seed to the ground from extending branches and repeating the process.
15. By creeping rootstocks, as June grass, quack grass and toad-flax.
16. By piercing potatoes, carrots, etc. Quack grass, June grass, Bermuda
grass are sometimes carried to other fields or farms where the tubers and
roots are planted.
17. As every kind of weed goes onto a farm to stay there, it follows that
as a country becomes older the greater the number of kinds of weeds. As
a rule, each farm is annually getting more sorts of weeds, and as each farmer
is cultivating weeds, they are more freely distributed in every field and along
every roadside, and by exchanging seeds, they are carried to neighboring farms.
A great many farmers buy and sow whatever the merchant offers them
under the name mentioned. For example, I have a sample of something
called clover seed, sold by a dealer in this state. It contains about 40%
of narrow-leaved plantain, which I consider one of the worst of clover weeds.
A large majority of weeds hail from older countries, more especially from
Europe.
There are a few weeds, like Canada thistle and quack grass, that may
infest any crop of farm or garden, but in most cases, whether to call a weed

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very bad depends on the nature of the crop grown, the size of the seed, and
their time of ripening.

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 soil and others in wet soil. 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 thrive and seed freely.

In many respects the list 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, 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. When the thrifty farmer screens out the smaller grains of wheat
to get the large grains for seed, by the same process he has screened out seeds
of cockle, and unintentionally bred up a race that bears larger seeds.

Meadows and pastures, especially where the land is not fertile, abound in
weeds that require two or more years to produce seeds, such as narrow-leaved
dock, bitter dock, bull thistle, carrot, teasel, two kinds of mullein, 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, the pigeon grasses. As crops of corn, potatoes, beans, turnips,
beets, 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.

WHAT ENABLES A PLANT TO BECOME A WEED?

1. Sometimes by producing an enormous number of seeds. A large plant
of purslane produces 1,250,000 seeds; a patch of daisy fleabane, 3,000 seeds
to a square inch.
2. In other cases by the great vitality of their seeds. Shepherd's Purse,
purslane, mustard, mayweed, pepper grass, evening primrose, smart weed,
narrow-leaved dock, chickweed, pigweeds, pigeon grass, survive for 25 years
or more, as I have proved by testing them.
3. Some plants are very succulent, and ripen seeds even when pulled.
(Purslane).
4. Often by ripening and scattering seeds before the cultivated crop is
mature. (Red root, fleabue).
5. Sometimes by ripening seeds at the time of harvesting a crop, when all
are harvested together. (Chess, cockle).
6. Some seeds are difficult to separate from seeds of the crop cultivated.
(Sorrel, mustard, narrow-leaved plantain and the two pigeon grasses).
7. Some weeds are very small and escape notice. (Mullein, fleabane).
8. Some plants go to seed long before suspected, as no showy flowers
announce the time of bloom. (Pigweeds).

9. In a few cases the plants break loose from the soil when mature and
become tumble weeds. (Some pigweeds, Russian thistle, winged pigweed).
10. Some remain with the dead plant long into winter, and when torn
off by the wind or by birds, drift for long distances on the snow, often from
one farm to another. (Pigweeds).
11. Some seeds and seed-like fruits are furnished each with a balloon,
or a sail, or with grappling hooks. (Dandelion, sticktights, burdock).

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12. Two seeds in the fruit of cockle bur are so placed that one grows the
first year, and the other remains dormant till the second year.
13. Some have creeping rootstocks or tubers. (Quack grass, nut-grass).
14. Some weeds defend themselves with forks and bayonets. (Thistles).
15. Stout rooted plants are skipped by the cultivator. (Dock).
16. Most of them are disagreeable in taste or odor, so that domestic animals
leave them to occupy the ground and multiply. (Jamestown weed, stink
grass, milkweed).
I have recently examined 122 samples of clover seeds, which contained
51 kinds of weed seeds; 9 samples of this number contained no weed seeds.
Seventy samples of clover seed contained seeds of Chaetochloa viridis
(green foxtail).
Sixty samples contained Plantago lanceolata (buckhorn).
Fifty-eight samples contained Plantago Rugelii (Rugel's plantain).
Fifty samples contained Rumex crispus (narrow-leaved dock).
Forty-six samples contained Rumex acetosella (sheep sorrel).
Thirty-six samples contained Polygonum Persicaria (lady's thumb).
Thirty samples contained Chenopodium album (lamb's quarters).
Twenty-three samples contained Plantago major (one of the broad-leaved
plantains).
Twenty-three samples contained Panicum Crus-galli (barnyard grass).
Twenty-one samples contained Ambrosia artemisiaefolia (common rag-
weed).
Seventeen samples contained Panicum capillare (hair grass).
Sixteen samples contained Panicum sanguinale (crab grass).
Fifteen samples contained Potentilla Monspeliensis.
Fourteen samples contained Amaranthus retroflexus (our most common
rough pigweed).
Thirteen samples contained Lepidium Virginicum (one of the pepper
grasses).
Nine samples contained Chaetochloa glauca (yellow foxtail).
Nine samples contained Alsine media (our most common chickweed).
Eight samples contained Nepeta Cataria (catmint).
Seven samples contained Lepidium apetalum (a small pepper grass).
Six samples contained Prunella vulgaris (self heal).
Five samples contained Cerastium vulgatum (mouse-ear chickweed).
Four samples contained Bromus secalinus (common chess).
Three samples contained Rumex obtusifolius (broad-leaved dock).
Three samples contained Anthemis Cotula (Mayweed).
Three samples contained Onagra biennis (evening primrose).
Three samples contained Daucus carrota (wild carrot).
Two samples contained Panicum lineare (narrow-leaved panicum).
Two samples contained Lithospermum arvense (red root).
Two samples contained Lolium perenne (perennial rye grass).
Two samples contained purslane.
Two samples contained Cichorium Intybus (chickory).
Two samples contained Brassica nigra (black mustard).
Two samples contained Carduus arvensis (Canada thistle).
Two samples contained Cuscuta arvensis (dodder).
Two samples contained Verbena urticifolia (nettled-leaved verbena).
One sample contained Medicago lupulina (black medick).
One sample contained Ranunculus bulbosa (bulbous crowfoot).
One sample contained Ranunculus repens (creeping crowfoot).

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One sample contained Sinapis arvensis (white mustard).
One sample contained Verbena hastata (blue vervain).
One sample contained Chaetochloa Italica (Hungarian grass).
One sample contained Carduus lanceolata (bull thistle).
One sample contained Arenaria serpyllifolia (a chickweed).
One sample contained Amaranthus graecizans (a tumble weed).
One sample contained Solanum rostratum (beaked nightshade).
One sample contained Lepidium campestre (a common peppergrass).
One sample contained Silene vulgaris (bladder campion).
East Lansing, April 1, 1909.