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A tumbleweed is a structural part of the above-ground anatomy of a number of species of . It is a diaspore that, once mature and dry, Abscission from its root or stem and rolls due to the force of the wind. In most such species, the tumbleweed is in effect the entire plant apart from the root system, but in other plants, a hollow fruit or inflorescence might detach instead. Xerophyte tumbleweed species occur most commonly in steppe and arid , where frequent wind and the open environment permit rolling without prohibitive obstruction.
Apart from its primary vascular system and roots, the tissues of the tumbleweed structure are dead; their death is functional because it is necessary for the structure to degrade gradually and fall apart so that its or can escape during the tumbling, or germinate after the tumbleweed has come to rest in a moist location. In the latter case, many species of tumbleweed open mechanically, releasing their seeds as they swell when they absorb water. page 16
The tumbleweed diaspore seed dispersal seeds, but the tumbleweed strategy is not limited to the Spermatophyte; some species of spore-bearing —such as Selaginella—form tumbleweeds, and some fungi that resemble puffballs dry out, break free of their attachments and are similarly tumbled by the wind, dispersing spores as they go.
In the family Amaranthaceae sensu (i.e. broadly defined to include Chenopodiaceae), several annual species of the genus Salsola are tumbleweeds. They are thought to be native to Eurasia, but when their seeds entered North America in shipments of agricultural seeds, they became naturalized in large areas. In the cinema genre of Westerns, they have long been symbols of frontier areas. Salsola tragus is the so-called "Russian thistle". It is an annual plant that breaks off at the plant stem base when it dies, and forms a tumbleweed, dispersing its seeds as the wind rolls it along. It is said to have arrived in the United States in shipments of flax seeds to South Dakota, perhaps about 1870. It now is a noxious weed throughout North America, dominating disturbed habitats such as roadsides, cultivated fields, eroded slopes, and arid regions with sparse vegetation. Though it is a troublesome weed, Kali tragus also provides useful livestock forage on arid rangelands. eFloras.org
Other members of the Amaranthaceae (s.l.) that form tumbleweeds include Kochia species, page 477
Among the Amaranthaceae (Sensu) that form tumbleweeds, there are several species of Amaranthus, such as Amaranthus albus, native to Central America but invasive in Europe, Asia, and Australia; and Amaranthus graecizans, native to Africa, but naturalized in North America. Amaranthus retroflexus, which is indigenous to tropical North and South America, has become nearly cosmopolitan largely as a weed, but like many other species of Amaranthus, it also is widely valued as animal forage and as human food, though it should be utilised with caution to avoid toxicity.
Several Southern African Genus in the family Amaryllidaceae produce highly optimised tumbleweeds; their are globular with long, spoke-like pedicels, either effectively at ground level, or breaking off once the stems are dry. When the seeds are about ripe, the fruit remain attached to the peduncles, but the stem of the umbel detaches, permitting the globes to roll about in the wind. The light, open, globular structures form very effective tumbleweed diaspores, dropping their seeds usually within a few days as the follicles fail under the wear of rolling. The seeds are fleshy, short-lived, and germinate rapidly where they land. Being poisonous and distasteful, they are not attractive to candidate transport animals, so the rolling diaspore is a very effective dispersal strategy for such plants. Genera with this means of seed dispersal include Ammocharis, Boophone, Crossyne and Brunsvigia.
Some species of the Apiaceae form tumbleweeds from their flower umbels, much as some Amaryllidaceae do.
In the Asteraceae, the knapweed Centaurea diffusa forms tumbleweeds. It is native to Eurasia and is naturalized in much of North America. Also in the Asteraceae, Lessingia glandulifera, native to America, sometimes forms tumbleweeds; it grows on sandy soils in desert areas, chaparral, and open pine forests of the western United States. eFloras.org
In the Brassicaceae, Sisymbrium altissimum, Crambe maritima, Lepidium, and a resurrection plant, Anastatica form tumbleweeds.
In the Caryophyllaceae, the garden plant "baby's-breath" ( Gypsophila paniculata), produces a dry inflorescence that forms tumbleweeds. In parts of central and western North America, it has become a common weed in many locations including hayfields and pastures. eFloras.org
In the legume family (Fabaceae), Baptisia tinctoria and some species of Psoralea produce tumbleweeds. In Psoralea the tumbleweed detaches from the plant by abscission of the stem.
In the Plantaginaceae, Plantago cretica forms tumbleweeds.
Inflorescences that act as tumbling diaspores occur in some Poaceae, including Schedonnardus paniculatus and some species of Eragrostis and Aristida.
In these plants, the inflorescences break off and tumble in the wind instead of the whole plant, much as happens in some of the Apiaceae and Amaryllidaceae. The species of Spinifex from Southeast Asia are prominent examples of this dispersal adaptation. (2025). 9780643091610, CSIRO Publishing. ISBN 9780643091610 These grasses are often called tumble-grasses, including such species as Panicum capillare and Eragrostis pectinacea in the United States.
In the Solanaceae, Solanum rostratum forms tumbleweeds.
Wind dispersed fruits that tumble or roll on the ground, sometimes known as "tumble fruits", are rare. Some are technically achenes. Highly inflated indehiscent fruits that may facilitate tumbling include Alyssopsis, Coluteocarpus, Physoptychis, Sutherlandia, and Physaria.
(2002). 9783540428732, Springer. ISBN 9783540428732
Very similar in habit to Anastatica, but practically unrelated, are the spore-bearing Selaginella lepidophylla (a Lycopodiophyta) and earthstar mushroom family (Geastraceae). All of these curl into a ball when dry and uncurl when moistened.
Bovista, a genus of puffball, uses essentially the same dispersal strategy.
Some ruderal species that disperse as tumbleweeds are serious weeds that significantly promote wind erosion in open regions. Their effects are particularly harmful to dryland farming where the outside application of additional moisture is not practicable. One study showed that a single Russian thistle can remove up to of water from the soil in competition with a wheat crop in one year.
It sometimes happens that species of large tumbleweed, especially if thorny, can form aggregations that are physically hazardous and can block roads and cover buildings and vehicles. This can happen where fences and similar obstacles cause the accumulation, but the weeds can also entangle each other until they form piles that can no longer roll. Such piles can be a serious threat to trapped vehicles or buildings and their occupants, particularly because they are dry and flammable. Examples of enveloped buildings and vehicles have been documented mainly in the Western regions of the US. In residential areas, an example was the town of Mobridge, South Dakota, where in 1989 tens of tons of large tumbleweeds ("Russian thistles") that had matured in the dry bed of nearby Lake Oahe buried many houses so deeply that mechanical equipment was necessary to remove it, release occupants and counter the fire hazard.
There was a significant outbreak of Panicum effusum in the town of Wangaratta in February 2016 that attracted international attention. The seed heads of the weed, known locally as "hairy panic", had piled several meters deep in some places, forcing residents to spend several hours removing it to regain access to their homes. The local council subsequently indicated it was considering attaching large vacuums to street-sweepers in an attempt to control the outbreak.
On 18 April 2018, strong winds and neglected maintenance of neighboring private land brought a large number of tumbleweeds into Victorville, California. Approximately 100 to 150 homes required help from public services after their entryways were at least partly blocked. The local fire department participated in the cleanup as the influx of tumbleweeds presented both a safety and fire hazard.
A similar incident occurred on 31 December 2019, when high winds dislodged a large number of tumbleweeds on the Hanford Site northwest of Richland, Washington. The tumbleweeds piled up deep in some areas, burying cars and trucks and closing Washington State Route 240 for ten hours while road crews used snowplows to remove the tumbleweeds.
Tumbleweeds have been observed causing problems with wastewater treatment plants. In some cases of inadequate fencing, they can get entangled in electromechanical equipment such as clarifiers and mechanical aerators leading to increased energy use and labor cost associated with operating and cleaning.
Bramblin and Brambleghast are Pokémon based on tumbleweeds.
Once dry and uprooted, tumbleweeds form steppicursors that, driven by the wind, roll on the lands of Southern California, Arizona, Nevada, Utah, New Mexico, Texas, northwestern Mexico, and most of the Mexican territory just south of the border. In the area of Mexicali they are called , which is also a demonym for those born and residing in that capital city of Baja California.
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