'' tumbleweed caught against a fence The tumbleweed dispersal strategies are unusual among plants; most species disperse their seeds by other mechanisms. Many tumbleweeds
establish themselves on broken soil as
opportunistic agricultural
weeds. Tumbleweeds have been recorded in the following plant groups: •
Amaranthaceae (including
Chenopodiaceae) •
Amaryllidaceae •
Asphodelaceae •
Asteraceae •
Brassicaceae •
Boraginaceae •
Caryophyllaceae •
Fabaceae •
Lamiaceae •
Poaceae '' In the family
Amaranthaceae s.l. (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
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. '' in flower in the
veld, showing the globular umbels of tumbleweed Amaryllidaceae '', a
North African desert tumbleweed '', a
North American desert tumbleweed Other members of the Amaranthaceae (s.l.) that form tumbleweeds include
Kochia species,
Cycloloma atriplicifolium, and
Corispermum hyssopifolium,
Atriplex rosea is called the tumbling oracle or tumbling orach. Among the Amaranthaceae (
s.s.) 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
genera in the family
Amaryllidaceae produce highly optimised tumbleweeds; their
inflorescences are globular
umbels 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
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. 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
grasses, 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. 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 Very similar in habit to
Anastatica, but practically unrelated, are the spore-bearing
Selaginella lepidophylla (a
lycopod) 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. ==Environmental effects==