In the Caryophyllaceae, the garden plant "baby's-breath" ( Gypsophila paniculata), produces a dry inflorescence that forms tumbleweeds. In the Brassicaceae, Sisymbrium altissimum, Crambe maritima, Lepidium, and a resurrection plant, Anastatica form tumbleweeds. 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.
It is native to Eurasia and is naturalized in much of North America. In the Asteraceae, the knapweed Centaurea diffusa forms tumbleweeds. Some species of the Apiaceae form tumbleweeds from their flower umbels, much as some Amaryllidaceae do. Genera with this means of seed dispersal include Ammocharis, Boophone, Crossyne and Brunsvigia. 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. The seeds are fleshy, short-lived, and germinate rapidly where they land. 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. 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. 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. 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. Īmong 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. Atriplex rosea is called the tumbling oracle or tumbling orach. Other members of the Amaranthaceae (s.l.) that form tumbleweeds include Kochia species, Cycloloma atriplicifolium, and Corispermum hyssopifolium, which are called plains tumbleweed. Selaginella lepidophylla, a North American desert tumbleweed
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The tumbleweed diaspore disperses seeds, but the tumbleweed strategy is not limited to the seed plants some species of spore-bearing cryptogams-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 latter case, many species of tumbleweed open mechanically, releasing their seeds as they swell when they absorb water. Īpart 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 seeds or spores can escape during the tumbling, or germinate after the tumbleweed has come to rest in a wet location. Xerophyte tumbleweed species occur most commonly in steppe and arid ecosystems, where frequent wind and the open environment permit rolling without prohibitive obstruction. 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.
It is a diaspore that, once mature and dry, detaches from its root or stem and rolls due to the force of the wind. A tumbleweed is a structural part of the above-ground anatomy of a number of species of plants.
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