Imágenes de páginas

ing spring freshets. In addition to these plants, the pastures-throughout Iowa are, especially in the fall, troubled with weeds such as goldenrod, the large yellow-flowered goldenrod (Solidago rigida) being exceedingly common in native pastures after the cattle have been running in them all summer. Sometimes these pastures present a mass of yellow. Frequently the S. canadensis is found in similar situations. In low-lying districts, especially in swampy ground, the rose-flowered smartweed or shoestring (Polygonum Muhlenbergii) is common. This persistent perennial produces very long, thick, stout root stocks and grows so thickly that grass does not appear. Another weed which occurs in our low, wild meadows is the thistle (Cirsium iowense), a biennial which makes very little growth the first season, but the second season sends up a large much-branched stalk and produces numerous purple flowers. The allied bull thistle (C. lanceolatum) is especially troublesome in pastures in the timber lot, frequently growing in such large masses as to become decidedly noxious. Canada thistle is common in the East and Canada. Stock carefully feed around this plant, thus permitting its seed to be sown broadcast in the field. It is occasionally found in meadows also. The meadowsunflower (Helianthus grosseserratus) is common throughout the northern states, in draws; the artichoke (Helianthus tuberosus) also occasionally occurs. In the East, the ox-eye daisy (Chrysanthemum leucanthemum), as yet raré in Iowa, is a pernicious weed in meadows eastward. In the West the white weeds (Erigeron ramosus and E. annuus) take its place. In the South, boneset (Eupatorium) and ironweed (Vernonia) are common. Another plant which has recently come into notice as a troublesome weed is the rib plantain (Plantago lanceolata), which has been brought into our meadows with clover seed. It is much more common in the East than


in the West and is quite easily recognized by its perennial habit and its long leaves, which are close to the ground. The flower stalk is groove-angled and from one to two feet long. It bears a cylindrical spike of flowers somewhat like the common dooryard plantain, but much shorter. Like many of our other troublesome weeds it is a native of Europe. Another European vagrant, the sheep sorrel (Rumer Acetosella), is widely distributed in the country. The fact that this weed spreads freely by its running roots accounts for its appearance in mats. There is a widely prevalent opinion that ground on which it occurs lacks lime; but this is far from being the fact, since the weed is very common in soils which contain large quantities of calcareous matter. An ally of the preceding species is the curled dock (Rumer crispus). This pestiferous plant, widely distributed throughout the northern states to the Pacific coast, does much ... injury in meadows and pastures. The (ś, White weed e - a - rigeron ramosus) a best method of destroying it is to pull common weed in tim: it up by twisting the root and then othy and clover mead; removing it by a sudden pull or jerk. ..." the North and ast. (C. M. King.) Several other species of dock are common in low meadows, among them being the smooth dock (Rumer altissimus). Sneezeweed (Helenium autumnale) is extremely common in low ground in many portions of Iowa. This weed has sometimes caused much alarm among stockmen, as it is poisonous. In the South the narrow-leaved species (H. tenuifolium) is abundant.


The blue vervain (Verbena stricta), with hairy leaves and long spikes of blue flowers, is common in many pastures of the northern Mississippi valley. Yarrow is also common, not only in northern states, but across the continent, especially in dry pastures and meadows. Two weeds of the morning glory family are very frequently found in Iowa. One, the European bindweed (Convolvulus arvensis), has made its way from Illinois and Missouri, where it is already something of a pest, and is now seen in meadows in Iowa. The other, the common morning glory (C. sepium), very closely allied to the above, is common in low meadows, where it has long been known as a persistent, troublesome weed. It differs from the European bindweed in having much larger flowers and longer twining stems. It not only shuts out the light from the grass, but its presence in hay renders the latter less valuable. There is no method of exterminating this weed except by close pasturing and preferably using the pasture for hogs. It must be taken up root and all or it will not be subdued. Milkweed (Asclepias syriaca) is frequently troublesome in meadows of the north; the showy milkweed from Iowa to Utah and the swamp milkweed (A. incarnata) are also seen in low meadows of the North. Horse nettle (Solanum carolinense) is also frequently complained of. Allied to this is the buffalo bur (S. rostratum), a bushy annual which grows only in open places in the meadow and would not occur if the meadow were kept in good condition. It is common in the Rocky Mountain country and from Kansas to Texas. Cowbane (Cicuta maculata), belonging to the same family as the carrot, parsnip and celery, is a frequent inhabitant of low meadows in Iowa and is easily recognized by its white flowers borne in umbels. It is one of the most deadly poisonous plants of the North, the poison residing in the root. Many cases of poisoning of human


beings as well as of cattle have been reported in the United States. In the West there are several other kinds which are common, like the western cowbane (C. vagans). Squirrel-tail grass (Hordeum jubatum) has long been a troublesome pest in many parts of the West, especially in Wisconsin, Illinois, Nebraska, Wyoming and Utah. It is one of our worst meadow weeds. Though originally a native of the sandy seashores from Nova Scotia to Maryland, and the upper great lakes, it has spread from the lakes to adjoining prairie country and is now troublesome in both pastures and meadows. In the former, it may be removed by cutting the plant before it is mature. It frequently causes injuries to cattle that may result in death. Broom sedge (Andropogon virginicus) is a most troublesome weed in meadows from southern Missouri, southeast to Virginia. Sweet clover (Melilotus alba), one of the most common weeds of pastures, is regarded by bee keepers as a valuable honey plant; but in the North is little esteemed as a forage plant. In the South it is valuable for reclaiming waste land, as it grows not only on rich land, but will thrive in the poorest soil. Professors Tracy and Goff both recommend it as a soil renovator. Although occasionally useful in Iowa as a bee plant, a soil renovator, and a forage plant, we must nevertheless regard it as a weed. A few members of the mustard family are troublesome in the pastures and meadows of Iowa. Among these are pepper grass—Lepidium apetalum and L. virginicum— the former of which is abundant, especially in timothy seed. Its brown color enables it to be easily detected. The wild carrot (Daucus Carota) is common in the East in some clover meadows, having been introduced largely with clover seed. The bracted plantain looks much like buckhorn, but has narrower leaves. It is common in Missouri, Illinois, Iowa, Nebraska and Kansas, extending east as far as the Atlantic coast. Field dodder is common not only on native herbage clear across the continent, but also occurs on clover. The clover dodder appears in California, Utah, Colorado, Montana, Missouri, and Iowa on alfalfa and clover. Pepper grass (Lepidium virginicum) furnishes an impurity for alsike and blue grass. Persicaria, or lady's thumb (Polygonum Persicaria), and the two ragweeds are common in many meadows. Among the common weedy grasses are foxtail (Setaria glauca), crab grass (Digitaria sanguinalis) and barnyard grass (Echinochloa crus-galli). On the plains and ranches in Colorado and Utah occur many bad weeds. The Russian thistle (Salsola Kali, var. tenuifolia) is easily one of the most common weeds in eastern Colorado, coming up not only in the streets, but also along roadsides and in fields. In the early days of the Russian thistle it was thought that it would prove a very troublesome weed in the more humid conditions of our country. Thus far it has not, but in the West it has found ideal conditions for development. Another weed which has become abundant is the tumbling mustard (Sisymbrium altissimum), which is found in many places. It has light yellow, mustard-like flowers, and later stiff pods without leaves. Sweet clover grows everywhere along roadsides and streets in eastern Colorado and stands drought well. On some of the foothills and streets of the eastern slope of the Rockies a species of brome grass (Bromus tectorum) is becoming abundant. It is an annual which grows with very little moisture and is crowding out many more valuable grasses, and alfalfa. It is particularly common near Colorado Springs, Salt Lake Basin and in California. It has little value for forage purposes; the hay is light, and moreover the plant is injuri

« AnteriorContinuar »