Alyssum desertorum
(desert madwort)

Pictures

Picture	Title	Caption	Copyright
Title Habit Caption Alyssum desertorum (desert madwort); habit in gravel areas near Long John's Meadow, Tuolumne County, California, USA. June, 2011. Copyright ©Barry Breckling/CalPhotos/ - CC BY-NC-SA 3.0	Habit	Alyssum desertorum (desert madwort); habit in gravel areas near Long John's Meadow, Tuolumne County, California, USA. June, 2011.	©Barry Breckling/CalPhotos/ - CC BY-NC-SA 3.0
Title Habit Caption Alyssum desertorum (desert madwort); habit (with seeds) in gravel areas near Long John's Meadow, Tuolumne County, California, USA. June, 2011. Copyright ©Barry Breckling/CalPhotos/ - CC BY-NC-SA 3.0	Habit	Alyssum desertorum (desert madwort); habit (with seeds) in gravel areas near Long John's Meadow, Tuolumne County, California, USA. June, 2011.	©Barry Breckling/CalPhotos/ - CC BY-NC-SA 3.0
Title Seeds Caption Alyssum desertorum (desert madwort); seeds. Copyright Public Domain - released by the USDA-NRCS PLANTS Database/Steve Hurst	Seeds	Alyssum desertorum (desert madwort); seeds.	Public Domain - released by the USDA-NRCS PLANTS Database/Steve Hurst

Identity

Preferred Scientific Name

• Alyssum desertorum Stapf

Preferred Common Name

• desert madwort

Other Scientific Names

• Alyssum sartorii Heldr. ex Maire & Petitm.
• Alyssum turkestanicum var. desertorum (Stapf) Botsch
• Psilonema minimum Schur.

International Common Names

• English: desert alyssum; dwarf alyssum
• French: alysson des déserts
• Russian: burachok pustynnyi
• Chinese: ting ji

Local Common Names

• Denmark: steppe-grådodder
• Estonia: liiv-kilbirohi
• Germany: Steppen-Steinkraut
• Latvia: tuksneša alise
• Lithuania: mažasis laibenis
• Norway: havnedodre
• Poland: smagliczka drobna
• Sweden: stäppdådra

EPPO code

• AYSDE

Summary of Invasiveness

A. desertorum is an herbaceous plant native to central and eastern Europe, North Africa and Asia (from Turkey to Xinjiang in northwestern China). It has become naturalized in northern Europe as well as in western North America, where it is classed as an introduced species, a weed and a weak invader. A. desertorum is a weed predominately of disturbed areas such as overgrazed semiarid rangelands and areas affected by industrial activity. Its spread has been facilitated recently by the expansion of hydraulic fracturing ('fracking') of deep rock formations for methane or oil extraction. A. desertorum is an environmental threat mainly due to its displacement of native plant species, including a number of endangered species.

Taxonomic Tree

• Domain: Eukaryota
•     Kingdom: Plantae
•         Phylum: Spermatophyta
•             Subphylum: Angiospermae
•                 Class: Dicotyledonae
•                     Order: Capparidales
•                         Family: Brassicaceae
•                             Genus: Alyssum
•                                 Species: Alyssum desertorum

Notes on Taxonomy and Nomenclature

The genus Alyssum contains around 330 species. The species name A. desertorum was validly published by Otto Stapf (1886) for a specimen collected during an expedition to Persia (modern-day Iran) in 1882.

Dudley (1962) later divided A. desertorum into three varieties (var. desertorum, himalayensis and prostratum), distinguished on the basis of minor differences in fruit trichomes, but today no infraspecific taxa are recognised (The Plant List, 2013). Recently, however, Plazibat (2009) in his study of the tribe Alysseae in the Croatian flora identified a putative new variety, A. desertorum var. socolacicum var. nov. This variety is noted in Missouri Botanical Garden (2015) but not currently not recognised by The Plant List (2013).

Description

A. desertorum is a self-compatible, autogamous, herbaceous annual with erect, ascending, or decumbent, stems 5-18 cm tall, sometimes reaching 28 cm. Leaves are cauline, arranged alternately on the stem; they are linear to oblanceolate-linear in shape, with a sharply pointed tip and are 0.3-3.0 x 0.5-4.0 mm in size. The entire plant except for the fruit is covered with 8-20 rayed uniformly stellate trichomes, giving the plant a canescent appearance. Inflorescences are up to 10 cm long with 30-40 flowers on stout, straight, ascending pedicels 1.0-4.5 mm long. The flowers form from the bottom up as the inflorescence grows. Flowers are small, less than 2.5 x 0.6 mm in size, with 4 pale yellow, oblanceolate, apically obtuse or retuse petals widest at the tip. There are 30-40 flowers per plant. The fruiting pods or silicles are 2.5-4.5 mm in diameter, circular in outline with a shallow notch at the tip where the short style persists, uniformly inflated at the middle and broadly flattened at the margins and often glaucous. There are often 2 ovules per locule and 2 locules per pod. The locules are separated by a thin membrane that persists and is obvious on the dried, senescent plant. Seeds are brown, ovate, slightly compressed, very narrowly winged at the margins and 1.2-1.5 x 0.9-1.1 mm in size (Flora of North America Editorial Committee, 2010; Jacobs, 2012; Flora of China, 2015).

Plant Type

Distribution

In Europe there is confusion about the status of A. desertorum in the Baltic States, with some sources claiming it to be native and others that it is an introduction. USDA-ARS (2015), for example, lists the species as being both native and naturalized in Latvia, Lithuania and Estonia.

The status of A. desertorum in Tibet is uncertain as it was not recorded in Flora Xizangica Vol. 2 (Wu, 1985) and it seems its presence is solely based on the holotype of A. desertorum var. himalayense collected in the 1830s in the Himalayas on the Tibet border.

In the USA, the Jepson Flora Project (2014) noted the presence of A. desertorum in disturbed areas and rocky sagebrush flats at an altitude of 1000–1500 m in California's Inner South Coast Ranges and Modoc Plateau, with the range extending to Washington and Nebraska. According to Johnson (1999) A. desertorum has been identified as an alien invasive in a number of national parks, including Yellowstone National Park (which is primarily located in Wyoming but also extends partially into Idaho and Montana), Bighorn Canyon National Recreation Area (in the northern Rockies of Wyoming and Montana), Devil's Tower National Monument (northeastern Wyoming), Little Bighorn National Battlefield Monument (Montana) and Wind Cave National Park (South Dakota). It is in Yellowstone National Park that much research into A. desertorum control has been undertaken.

Distribution Table

The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.

History of Introduction and Spread

According to Mosley (2014), A. desertorum was introduced into the USA by migrants from Europe and/or Asia to be grown for its traditional medicinal properties (including as a cure for hiccoughs, rabies and mental illness) but was not reported until 1941. T. R. Dudley, writing in 1968, observed that A. desertorum had a narrower distribution in the USA than Alyssum alyssoides, another introduction from Europe/Asia (Dudley, 1968). At the time only sporadic populations of A. desertorum were known from: Bannock County, Idaho; Missoula County, Montana; Sheridan County, Wyoming; and San Juan County, Utah. However, Rollins (1981; 1993) reported that the species is abundant on sheep rangelands in the Rocky Mountains and Great Basin region. In the Lower Muddy Creek Watershed in Wyoming, transects in 2009 that did not include A. desertorum 10 years previously, then reported it as the dominant species (BLM Wyoming, 2014). This area had recently experienced intensive coalbed methane drilling activity and hence, site disturbance. A. desertorum with its relative A. alyssoides together occur as exotic aliens in 37 USA states and seven Canadian provinces (Mosley, 2014).

In Canada A. desertorum was first collected in 1944, at Indian Head in southeastern Saskatchewan by B. J. Sallans and R. C. Russell (CBIF, 2012). It was subsequently found in other areas of south Saskatchewan, south Alberta and southeast and south-central British Columbia. It is, however, not listed under the Plant Protection Act nor the Federal Weed Seeds Order (Plants of Canada Database, 2013).

Introductions

Risk of Introduction

According to Mosley (2014), writing about the situation in Montana, there is a perceived expansion in the range of A. desertorum with the species becoming more prevalent and problematic in the west, centre and south-east, although it is not listed as a noxious weed in the state. The reasons for the expansion in distribution are not clear, but climate change could be a cause, not only in Montana but throughout the western USA. Although there has been no research into the consequences of climate change per se on the spread of A. desertorum, recent serious droughts, for example, may have weakened established plant communities allowing invasion by Alyssum species which are more adapted to drought conditions. Mild winters favour A. desertorum seedling establishment and the adoption of reduced tillage of croplands by farmers may have encouraged the formation of environments more suitable for invasive species. Increased industrial activity, especially fracking, also favours the spread of A. desertorum by providing it with a suitable disturbed habitat to colonize. Seed of A. desertorum can adhere to both animals and vehicles and may be accidentally transported and introduced into new locations.

Habitat

In its native range, A. desertorum is found from near sea level up to an altitude of around 2600 m. It prefers arid and semiarid lands, deserts and rocky areas (Flora of China, 2015). Grubov (2001) indicates that in Mongolia A. desertorum is found on steppes, stony and debris-covered slopes and alkaline waterside gravels. In Poland, A. desertorum was identified as a species characteristic of xeric sand grasslands (Matuszkiewicz, 2001).

In North America, it is found at altitudes of 800-2000 m, in deserts, rocky areas, prairies, around grain elevators, railway beds, disturbed sites, roadsides, fields, meadows and sagebrush flats (Mulligan, 2002; Flora of North America Editorial Committee, 2015). Dry, gravelly areas on rangelands and croplands are also favoured.

Habitat List

Host Plants and Other Plants Affected

Biology and Ecology

Genetics

A. desertorum has a chromosome number of n = 16 (Mulligan, 1964); 2n = 32 (Murín et al., 1999).

Reproductive Biology

A. desertorum is an annual forb that propagates by seed. With its coloured flowers, pollination is assumed to be entomophilous (FloraGREIF, 2010). Khan (2003) reports on the pollen morphology of seven Alyssum species, including A. desertorum, from Pakistan. Pollen grains are tricolpate with a reticulate tectum. Little variation between species was observed in shape, size, colpi length and exine pattern, but a palynological key to the species is provided. According to data collected in the Gurbantunggut Desert in northwest Xinjiang by Liu et al. (2014), seeds weigh 0.37 mg, are dispersed by rain drops (ombrohydrochory).

Physiology and Phenology

Plants flower in spring, with flowering, fruiting and seed dispersal occurring between March and July, depending on location. In North America plants flower and fruit from April to July, and from April to June in China. Plants die in summer after seed is shed. Seeds must after-ripen on the soil surface for several weeks before they can germinate. Most seeds will germinate in the current year. Germination rates of 93% have been recorded (Liu et al., 2014). Flowering and seed production are delayed following mild winters, allowing germination to occur in autumn when soil moisture is usually optimal for seedling survival. Although harsh winters promote early flowering and seed dispersal, seedling death is frequent under the subsequent hot, dry conditions of summer. The trichomes covering the plant that give it a greyish appearance help retain moisture, a feature typical of plants of arid and semiarid habitats.

Associations

In Poland, A. desertorum was identified as a species characteristic of xeric sand grasslands of the Koelerion glaucae [Koeleria glauca] complex and the association Cerastio-Androsacetum septentrionalis (Matuszkiewicz, 2001).

In western North America, it is invading big sagebrush (Artemisia tridentata) complexes (Bates et al., 2004).

Environmental Requirements

A. desertorum is found growing at altitudes from sea level to 2600 m in its native range and 800-2000 m in North America, its introduced range. A. desertorum is a temperate species which prefers free draining soil.

Climate

Latitude/Altitude Ranges

Soil Tolerances

Soil drainage

• free

Soil reaction

• alkaline
• neutral

Soil texture

• light
• medium

Special soil tolerances

• infertile

Natural enemies

Notes on Natural Enemies

Erysiphe cruciferarum was observed in 2005 infecting leaves of A. desertorum and A. hirsutum growing on a farm near Ankara in central Turkey (Karakaya, 2006). The same disease had previously been reported on A. desertorum in 1926 in Romania (HerbIMI, 2015). In 1977 Peronospora parasitica [Hyaloperonospora parasitica] was also reported on A. desertorum in Romania (HerbIMI, 2015).

Means of Movement and Dispersal

Natural Dispersal

A. desertorum exhibits ombrohydrochorous (rain assisted) seed dispersal (Liu et al., 2014).

Vector Transmission

Seeds of A. desertorum are carried on the bodies of animals, or are eaten in forage or in hay and subsequently excreted some distance away (Olliff et al., 2001). Western harvester ants (Pogonomyrmex occidentalis) predate on the seeds and are effective dispersal vectors (Mull, 2003).

Accidental Introduction

Roadsides and areas where ground disturbing activities take place are among the main habitats in which A. desertorum is found, indicating that seeds are transported on vehicles including construction and industrial equipment. Gravel and sand used in construction and roadways are often contaminated with weed seeds (Olliff et al., 2001).

Intentional Introduction

A. desertorum was originally introduced into North America as a medicinal garden plant, from where it spread into the wild (Mosley, 2014).

Pathway Causes

Pathway Vectors

Impact Summary

Economic Impact

One of the main economic impacts quantified with regard to A. desertorum is the actual cost of controlling the weed and restoring native plant communities to a pre-invasion status. In a pilot vegetation restoration project in the Gardiner Basin of Yellowstone National Park from 2008 to 2015, the actual plus projected costs amounted to US$1,013,459 for the eight years. This included the costs of native plant seed production, salaries, fencing contracts, equipment, herbicides, cover crop sowing and soil sampling which amounted to US$20,269 per acre (Renkin et al., 2014).

Environmental Impact

A. desertorum is a shallow rooted plant that can accelerate soil erosion. It also extracts surface soil moisture, thus impeding the establishment of seedlings of other more desirable species. Nersesyan and Shur-Bagdasaryan (1990) showed that heavy grazing in Armenia of steppe grasslands dominated by Festuca sulcata [Festuca rupicola] on sloping sites destroyed plant cover and increased water erosion of soil. Reduction in soil fertility was indicated by the development of drought resistant annual weeds, including A. desertorum, which had a negative effect on soil conservation.

Since the early 2000s, A. desertorum has greatly expanded its coverage in Gardiner Basin, an area of abandoned agricultural land and arid grassland ecosystem important as a wildlife corridor and winter range for large ungulates, including bison (Bison bison). Here it forms near-monocultures in some areas and is colonising surrounding landslides and mudflows, out-competing native vegetation and negatively altering soil biodiversity. Hamilton and Hellquist (2012) found that microbial community diversity was much lower in soils dominated by A. desertorum than in soils supporting native plant communities and even soils colonised by exotic perennial grasses. This resulted in negative effects on soil quality through decreases in soil organic matter, moisture-holding capacity, respiration rates and net ecosystem productivity. However, the invasion by A. desertorum had not affected the soils in which native Poa secunda was growing, indicating the persistence of native soil bacterial communities within invaded soils (Hamilton III et al., 2009).

In Wyoming, A. desertorum is invading areas such as the Lower Muddy Creek Watershed which are crucial winter ranges for antelope, deer and elk (Cervus canadensis) and are important for the greater sage grouse (Centrocercus urophasianus) as areas for over-wintering, brood-rearing and courtship (leks). A. desertorum is also displacing many native perennial plants through competition (BLM Wyoming, 2014).

In their experimental studies, Evangelista et al. (2011) found that the richness and overall coverage of disturbed land by A. desertorum, cheatgrass (Bromus tectorum), Japanese brome (Bromus japonicus) and other invasive weeds was generally increased by disturbance. As a result, the richness and coverage of native species was decreased. The native species in the region being typical of sagebrush steppe and mixed-grass prairie.

The Goose Creek milkvetch (Astragalus anserinus), a low-growing, matted, perennial forb, listed in the USA as a candidate species under the Endangered Species Act, grows only in a 26 km² area of the Goose Watershed of the Upper Snake River Basin in Idaho, Nevada and Utah. A survey of the species in 2011 in Utah by Shohet and Wolf (2011) found several non-native species growing at or immediately adjacent to milkvetch population sites. Many sites had both B. tectorum and A. desertorum in high concentrations, threatening the survival of these populations.

Threatened Species

Risk and Impact Factors

• Proved invasive outside its native range
• Has a broad native range
• Tolerates, or benefits from, cultivation, browsing pressure, mutilation, fire etc
• Pioneering in disturbed areas
• Fast growing
• Has propagules that can remain viable for more than one year

• Damaged ecosystem services
• Ecosystem change/ habitat alteration
• Modification of nutrient regime
• Monoculture formation
• Negatively impacts agriculture
• Reduced native biodiversity
• Threat to/ loss of endangered species
• Threat to/ loss of native species

• Competition - monopolizing resources
• Herbivory/grazing/browsing

• Highly likely to be transported internationally accidentally
• Difficult to identify/detect as a commodity contaminant
• Difficult/costly to control

Uses

Economic Value

Hovsepyan and Willcox (2008) analysed charred plant remains and impressions of chaff in pisé (mud brick) from the Neolithic sites of Aratashen and Aknashen (sixth millennium BC.) in the Ararat valley in Armenia. They discovered that along with barley (Hordeum vulgare) and wheat (Triticum species), two lesser known crucifers, Camelina microcarpa and A. desertorum, were frequently present in the form of crop processing residues. This indicates that in prehistory they were important, grown or collected, perhaps as sources of seed oil.

Today, A. desertorum is grown as a minor oilseed crop in parts of western Asia. In on-farm trials in Shahrekord in Iran, Yadegari and Shakerian (2014) tested the effects of irrigation periods and iron and zinc foliar feeds on the agronomic characteristics of Borago officinalis, Calendula officinalis, Thymus vulgaris and A. desertorum. Results found that applying iron and zinc at 400 ppm, with irrigation every three days, gave the highest seed yields.

A. desertorum is part of the southern steppe plant community in Ukraine and as such has been used as fodder.

Environmental Services

The seeds of A. desertorum are an important food source for several animals, including the desert hamster (Phodopus roborovskii) in its native range across northeastern China and Mongolia (Ross, 1994). The steppe tortoise, Testudo horsfieldii (an IUCN red list vulnerable species) is native to Central Asia and feeds during its mating season on leaves, flowers and fruits of A. desertorum (Lagarde et al., 2003).

In its introduced range, seed predation by western harvester ants (Pogonomyrmex occidentalis) has been observed in Wyoming (Mull, 2003) and in Yellowstone National Park A. desertorum is browsed by pronghorn antelopes (Antilocapra americana) in winter (Boccadori et al., 2008).

Uses List

Animal feed, fodder, forage

• Fodder/animal feed
• Forage

Human food and beverage

• Oil/fat

Materials

• Oils

Medicinal, pharmaceutical

• Traditional/folklore

Diagnosis

Presence of A. desertorum can be determined by visual inspection of plants and seeds.

Detection and Inspection

Rew et al. (2007) in their survey of non-indigenous plant species, including A. desertorum, in the Northern Range of Yellowstone National Park in 2001-2004, surveyed along transects to allow data to be collected continuously and a large sample size to be generated. Surveying along transects allowed changes in underlying environmental variables to be recorded, which was important for estimating the geographic distribution of the species from the sample data. Transects established perpen­dicular to roads and trails were accepted as the most effective sampling methodology. At a length of 2000 m, transects were sufficiently long to cross a number of habitat types. Paired transects were used to maximize surveying time while in the field. Transects were walked and survey observations were made within a 10 m wide swath. Surveys over an area of 529,000 m x 10 m in the Park's Northern Range found A. desertorum to be one of nine species that were observed to occur over more than 1% of the surveyed area (Rew et al., 2007).

Similarities to Other Species/Conditions

Commenting on introduced Alyssum species in the USA, Dudley (1968) noted that A. desertorum was often confused with but could be easily distinguished from the very similar A. alyssoides. A. desertorum is identifiable by its larger and glabrous silicles and early deciduous sepals; in A. alyssoides the silicles always possess an indumentum of stellate trichomes and the sepals are persistent. Both species grow on dry, gravelly areas on rangelands and croplands, but A. desertorum occupies harsher, rockier sites at lower elevations (Mosley, 2014).

Weeds mistaken for A. desertorum in Montana include hoary alyssum (Berteroa incana), a Priority 2A noxious weed in the state and whitetop (Lepidium draba) a Priority 2B noxious weed. B. incana is taller than A. desertorum with white flowers which bloom from May to September. L. draba is also taller than A. desertorum with white-flowers, but is also perennial and with leaves covered in straight rather than stellate trichomes (Mosley, 2014).

In the Tianshan Mountains of central Asia, A. desertorum is similar to Arabidopsis thaliana in terms of ecological requirements and habitats (Jacobs, 2012).

Prevention and Control

Prevention

SPS Measures

As A. desertorum can be transported in hay, only certified weed-free hay is allowed in or through Yellowstone National Park (Olliff et al., 2001).

Cultural Control and Sanitary Measures

To eliminate A. desertorum seed from being transported in gravel, any gravel destined for use in Yellowstone National Park has to be from a source operating a weed management plan or has to be heated to 150°C (Olliff et al., 2001).

Control

Physical/Mechanical Control

A native grass restoration project in the northern boundary area of Yellowstone National Park north of Gardiner, Montana, found that applying prescribed burns in October significantly reduced A. desertorum numbers the year following the burns (Jacobs, 2012). However, Bates et al. (2004) found that burning of Wyoming big sagebrush (Artemisia tridentata subsp. wyomingensis) by wildfires substantially increased A. desertorum cover.

Chemical Control

A number of herbicides, including metsulfuron and glyphosate, are known to temporarily reduce populations of A. desertorum (Jacobs, 2012). In the Lower Muddy Creek Watershed in Wyoming, small plot treatments were started in 2009 with a variety of different chemicals and rates to test for the most efficient and cost-effective treatment. Preliminary results show a 75-90% reduction in A. desertorum cover, a 15-75% increase in grass cover and a 100% increase in bare ground after treatments (BLM Wyoming, 2014). Removal of A. desertorum in this area would improve or maintain the habitat for wildlife and livestock using the area.

IPM and Ecosystem Restoration

A pilot native plant community restoration project was undertaken in the Gardiner Basin of the Yellowstone National Park, USA in 2008-14. This project had an integrated approach to controlling A. desertorum. Treatments involved herbicide applications, hand pulling, burning, harrowing, construction of exclosures and planting a barley/wheat cover crop to stabilize the soil and stimulate soil biota. Preliminary results indicate that the management actions undertaken have increased the likelihood of long-term successful native vegetation restoration (Renkin et al., 2014). A vigorous native plant community can help prevent invasion of an area by weedy species (Olliff et al., 2001).

Gaps in Knowledge/Research Needs

Research into the effects of climate change on A. desertorum is needed, as well as more assessments on the impact of fracking on native plant communities and alien plant invasions.

References

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Contributors

15/02/2015 Original text by:

Andrew Praciak, Carne, Wexford, Ireland.

Distribution Maps