Holcus lanatus - L.
Common Velvet Grass
Other English Common Names: Common Velvetgrass
Other Common Names: common velvetgrass
Taxonomic Status: Accepted
Related ITIS Name(s): Holcus lanatus L. (TSN 41773)
Unique Identifier: ELEMENT_GLOBAL.2.151209
Element Code: PMPOA37010
Informal Taxonomy: Plants, Vascular - Flowering Plants - Grass Family
 
Kingdom Phylum Class Order Family Genus
Plantae Anthophyta Monocotyledoneae Cyperales Poaceae Holcus
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Concept Reference
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Concept Reference: Kartesz, J.T. 1994. A synonymized checklist of the vascular flora of the United States, Canada, and Greenland. 2nd edition. 2 vols. Timber Press, Portland, OR.
Concept Reference Code: B94KAR01HQUS
Name Used in Concept Reference: Holcus lanatus
Conservation Status
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NatureServe Status

Global Status: GNR
Global Status Last Changed: 22Mar1994
Rounded Global Status: GNR - Not Yet Ranked
Nation: United States
National Status: NNA
Nation: Canada
National Status: NNA (12Oct2016)

U.S. & Canada State/Province Status
United States Alabama (SNA), Alaska (SNA), Arizona (SNA), Arkansas (SNA), California (SNA), Colorado (SNA), Connecticut (SNA), Delaware (SNA), District of Columbia (SNA), Georgia (SNR), Hawaii (SNA), Idaho (SNA), Illinois (SNA), Indiana (SNA), Iowa (SNA), Kansas (SNA), Kentucky (SNA), Louisiana (SNA), Maine (SNA), Maryland (SNA), Massachusetts (SNR), Michigan (SNA), Mississippi (SNA), Missouri (SNA), Montana (SNA), Nevada (SNA), New Hampshire (SNA), New Jersey (SNA), New Mexico (SNA), New York (SNA), North Carolina (SNA), North Dakota (SNA), Ohio (SNA), Oklahoma (SNA), Oregon (SNA), Pennsylvania (SNA), Rhode Island (SNA), South Carolina (SNA), Tennessee (SNA), Texas (SNA), Utah (SNA), Vermont (SNA), Virginia (SNA), Washington (SNA), West Virginia (SNA), Wisconsin (SNA)
Canada British Columbia (SNA), New Brunswick (SNA), Newfoundland Island (SNA), Nova Scotia (SNA), Ontario (SNA), Quebec (SNA)

Other Statuses

NatureServe Global Conservation Status Factors

Range Extent Comments: Velvet grass is of European origin, its center of origin thought to be the Iberian peninsula (Jacques and Munro 1963), and is a native of temperate areas of Europe and Asia (Scoggan 1978). It was probably introduced to North America either accidentally as a contaminant of forage seed or deliberately as a component of seed mixtures for meadow (Thompson and Turkington 1988). It has since spread and become locally abundant from British Columbia to Nova Scotia, Canada, south from Maine to Kansas and Colorado, south to Georgia and Louisiana and in primarily moist areas below 7500 feet along the Pacific Coast from British Columbia to California and to Montana and Arizona (Thompson and Turkington 1988).

Velvet grass is common throughout Europe except the extreme north and northeast where it is only casual (Thompson and Turkington 1988). In England, it is widely distributed in fields, partic- ularly on north-facing slopes (Grime and Lloyd 1973). The grass is now found throughout Asia, Africa, New Zealand, Australia, and sub- Antarctic islands. It has escaped cultivation and become a weed pest along roadsides, fencerows, ditch banks, in old pastures, and other disturbed sites, particularly in moist places (Muenscher 1955). In the Coast Ranges, it has become a weed of minor importance (Robbins et al. 1970).

Overall Threat Impact Comments: HOLCUS LANATUS is present on Oregon and Washington westside grassland preserves and the Northern Califoria Coast Range Preserve. It is apparently not a major problem species on Nature Conservancy lands in California, but where it occurs, control may be difficult due to its prolific seeding ability and its possible allelopathic effect on native grasses. It has, however, become a major problem on western Oregon and Washington grassland preserves.

Short-term Trend: Increase of >10%

Other NatureServe Conservation Status Information

Distribution
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Global Range: Velvet grass is of European origin, its center of origin thought to be the Iberian peninsula (Jacques and Munro 1963), and is a native of temperate areas of Europe and Asia (Scoggan 1978). It was probably introduced to North America either accidentally as a contaminant of forage seed or deliberately as a component of seed mixtures for meadow (Thompson and Turkington 1988). It has since spread and become locally abundant from British Columbia to Nova Scotia, Canada, south from Maine to Kansas and Colorado, south to Georgia and Louisiana and in primarily moist areas below 7500 feet along the Pacific Coast from British Columbia to California and to Montana and Arizona (Thompson and Turkington 1988).

Velvet grass is common throughout Europe except the extreme north and northeast where it is only casual (Thompson and Turkington 1988). In England, it is widely distributed in fields, partic- ularly on north-facing slopes (Grime and Lloyd 1973). The grass is now found throughout Asia, Africa, New Zealand, Australia, and sub- Antarctic islands. It has escaped cultivation and become a weed pest along roadsides, fencerows, ditch banks, in old pastures, and other disturbed sites, particularly in moist places (Muenscher 1955). In the Coast Ranges, it has become a weed of minor importance (Robbins et al. 1970).

U.S. States and Canadian Provinces
Color legend for Distribution Map
NOTE: The distribution shown may be incomplete, particularly for some rapidly spreading exotic species.

U.S. & Canada State/Province Distribution
United States AKexotic, ALexotic, ARexotic, AZexotic, CAexotic, COexotic, CTexotic, DCexotic, DEexotic, GA, HIexotic, IAexotic, IDexotic, ILexotic, INexotic, KSexotic, KYexotic, LAexotic, MA, MDexotic, MEexotic, MIexotic, MOexotic, MSexotic, MTexotic, NCexotic, NDexotic, NHexotic, NJexotic, NMexotic, NVexotic, NYexotic, OHexotic, OKexotic, ORexotic, PAexotic, RIexotic, SCexotic, TNexotic, TXexotic, UTexotic, VAexotic, VTexotic, WAexotic, WIexotic, WVexotic
Canada BCexotic, NBexotic, NFexotic, NSexotic, ONexotic, QCexotic

Range Map
No map available.

Ecology & Life History
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Basic Description: HOLCUS LANATUS is a grayish, soft-pubescent, fibrous-rooted perennial grass.
Technical Description: The following description is adapted from Abrams (1940), Jepson (1951), Muenscher (1955), Munz and Keck (1973), Cronquist et al. (1977), and Thompson and Turkington (1988).

HOLCUS LANATUS is a fibrous-rooted, cespitose, loosely to compactly tufted, perennial grass (often short-lived) that reproduces by seeds and stolons (Watt and Haggar 1980a, Fletcher 1983). The plant is grayish and soft-pubescent with hairs reflexed, erect or ascending from prostrate or semiprostrate shoots with 2-5 nodes. The culms are (2) 4-10 (20) dm tall, sometimes decumbent at the base. The softly hairy (occasionally almost hairless), flat, greyish-green or green leaf blades are 3.5-8 (12) mm wide and (4) 10-20 cm long. Young leaves are rolled in the shoot. The sheaths are open almost to the base, the margins usually overlapping, usually with reflexed hairs and rounded on the back, slightly keeled and oval in section. There are no auricles at the base of the blade, but there is a membranous ligule 1.5-3 (4.2) mm long, truncate, erose-ciliate, and puberulent.

The panicle is contracted, pale, soft, 5-12 (20) cm long, often tinged with purple, but sometimes pale green or whitish, the branches and pedicels short, ascending, and hirsute. Spikelets are greyish-green, whitish or more often pinkish or purple, 3-6 mm long, laterally compressed, crowded, falling entire at maturity, usually two-flowered, the first floret perfect, the second usually staminate. The glumes are unequal, lanceolate, mucronate, ciliate on the keel and nerves, scabrid or puberulent to villous elsewhere. The first or lower glume is 3.5-5 mm long, lanceolate, and one- nerved; the second or upper is 3.8-5.5 (6) mm long, much broader, ovate, prominently three-nerved, sometimes glabrous between the midnerves and margins, and sometimes tipped with a small awn. Lemmas are small, 1.7-2.5 (3) mm long, enclosed within the glumes, smooth, shining, the upper one with an awn attached below a shallow cleft. The awn is 1-2 mm long, mainly smooth, straight when fresh becoming hook-like when dry. Paleas are hairy on the nerves and at the tip, notched, and usually three toothed. Lodicules are broadly lanceolate, acuminate, up to 0.5 mm long. The three anthers are 1.2-2.2 (2.5) mm long.

The caryopsis is enclosed by the hardened lemma and palea. The seed has a rugose surface with hairs directed upwards.

Diagnostic Characteristics: HOLCUS LANATUS is rarely mistaken for any other species with the possible exception of H. MOLLIS. H. LANATUS can be distinguished by the purplish coloration on the panicles and veins of the sheaths, soft hairs all over, and lack of rhizomes. The two species may be able to hybridize (Jones 1954).
Duration: PERENNIAL
Reproduction Comments: FLORAL BIOLOGY

In North America, flowering occurs June through August (Septem- ber). H. LANATUS is wind pollinated and predominantly an outcrossing species. Successful self-fertilization occurs only occasionally and is impossible in some plants (Beddows 1931). During anthesis the panicle opens from the apex down and closes likewise (Tutin et al. 1964).

SEED PRODUCTION

In England, HOLCUS LANATUS seeds are shed from June to September (Mortimer 1976). The plants require vernalization to flower, but this process is enhanced and, to a small extent, replaced by short- day treatment (Watt 1977). It flowers and produces seeds from the second year onwards and behaves as a "paucennial." In places with reduced competition, the plant will often die after a few years, particularly following luxuriant flowering. In southern Europe, very short-lived races that flower the first year are found in dry habitats. In northern races, the plants require a period of vegetative growth prior to flowering in the second year (Bocher and Larsen 1958). HOLCUS LANATUS also exhibits variation in culm length and growth habit. In exposed maritime habitats, it grows as a low plant, while farther inland, the plants are more erect with tall culms (Bocher and Larsen 1958).

Trapaidze and Gogiya (1981) report up to 850 wind-dispersed seeds per plant in the Soviet Union. In England, Watt (1976) found production of up to 240,000 seeds per plant, most of which germinated shortly after landing on moist soils.

SEED GERMINATION

Williams (1983) found that when stored under dry, shaded conditions, velvet grass seeds remained viable for at least 48 weeks with 90-99% germination. Trapaidze and Gogiya (1981) found a germination rate of 95% for the first two years after seed harvest. Both vertebrates and earthworms appear to significantly reduce velvet grass populations by their burial or consumption of seeds (Mortimer 1976). When the seeds were buried, only 3% of them were still viable after a year. Seeds buried at a depth of 1-2 cm had a much higher chance of emergence than those at a depth of 3 cm (Williams 1983). In the Soviet Union, HOLCUS seeds showed 87% germination rate on the ground surface, 76% at a depth of 1 cm, and only 5% germination at 2 cm (Trapaidze and Gogiya 1981). HOLCUS LANATUS seeds are thus apparently not innately dormant, though certain field conditions may enforce dormancy (Williams 1983). Even though most of the seeds are nondormant, the potential number of seeds produced by each plant is so high that even a 1% level of innate or enforced dormancy would result in a large amount of buried viable seed (Watt 1976). The species can thus exist in large numbers in a seed bank, even if it is not an important plant on a given site (Roberts 1982).

Seed germination can occur at 7-8 C (Trapaidze and Gogiya 1981). Thompson and Whatley (1984) suggest that burying the seeds may induce a requirement for fluctuating temperatures of greater than 19 C. The result is that HOLCUS LANATUS seeds germinate more readily in larger canopy gaps (wider than 25 cm) where their survival chances are improved (Thompson 1977). Mortimer (1976) estimates that when various mortality factors are taken into consideration, each HOLCUS LANATUS plant can produce 9.9 adult plants the following year.

HOLCUS LANATUS is not usually considered a stoloniferous species, but regeneration can occur by the formation of decumbent tillers in late summer that subsequently produce roots and shoots at the nodes. Growth of these shoots may be enhanced by grazing or mowing, but root growth does not appear to be affected (Watt and Haggar 1980a).

Known Pests: GAEUMANNOMYCES GRAMINIS, PLASMODIOPHORA BRASSICAE
Ecology Comments: Little research has been done on HOLCUS LANATUS in North America. In Europe, it is an adaptable, competitive species that tolerates a wide range of habitats, particularly acidic, low nutrient sites (Watt 1977).

GROWTH, PRODUCTIVITY, AND COMPETITION

In the Soviet Union, Trapaidze and Gogiya (1981) report that HOLCUS species have an exceptionally long growing season. Germination occurs from seed or as sprouts from roots in late autumn, with flowering between May and July. In a Dutch experiment (van Andel and Jager 1981), velvet grass leaf area peaked 15 weeks after sowing, and maximum dry weight was attained two weeks later. In the later stages of growth, root mass increased dramatically, reaching half of the total plant weight. Nitrogen levels also showed a marked increase after 15 weeks of growth. Nitrogen availability may be the limiting factor in HOLCUS LANATUS growth (Watt 1978). HOLCUS LANATUS normally occurs on soils of moderate to low fertility, but fertilization appears to improve its competitive ability (Remison and Snaydon 1980).

High water table levels reduce the productivity of velvet grass. HOLCUS manages to persist on these wet sites by producing a large number of fine roots on the soil surface where aeration and nutrient levels are higher (Watt and Haggar 1980b). Grootjans (1979) noted that a lowered water table increase the N-mineraliza- tion rate and the nitrate content leading to a strong site dominance by HOLCUS LANATUS. Severe winter weather and high ground water can kill the grass, perhaps by lowering the N-mineralization rate (Bakker et al. 1980). Velvet grass can tolerate soils with a pH range of 3 to 8.1 (Grime and Lloyd 1973) but does best on sites with a pH of 4.5 to 5.5 (Roberts 1982).

Like other weeds from disturbed but productive habitats, HOLCUS LANATUS is able to grow rapidly. The mean recorded growth rate is 1.56 g/g.week while the maximum growth rate exceeds 2 g/g.week (Redosevich and Holt 1984). This rapid growth may indicate a high potential competitive ability among crop and weed species (Redosevich and Holt 1984). This aggressiveness is shown in the dominance of velvet grass in English pastures (Turkington et al. 1979). HOLCUS also does well in both high and low levels of light (Anonymous 1976).

In an English study, Remison and Snaydon (1980) found that HOLCUS LANATUS outcompeted DACTYLIS GLOMERATA (orchard grass) under a wide variety of conditions. Velvet grass yield increased by 50% on sites with competition over sites where it was grown alone. Similar results are reported for competition between HOLCUS LANATUS and LOLIUM PERENNE (ryegrass). Velvet grass is particularly aggressive in root competition due to its higher proportion of roots than other British pasture species (Watt and Haggar 1980a).

In a Dutch grassland study (Bakker et al. 1980), HOLCUS LANATUS became dominant when the grass was mowed following maturation and seed dispersal. When earlier cuts were made, HOLCUS LANATUS survived but became less dominant. HOLCUS LANATUS responds well to cutting, even when cut back to only 2 cm above the ground. On unharvested sites, velvet grass gradually forces other plants out, reducing species diversity. This process is particularly apparent on unfertilized sites. Allelopathy may also play a role in the dominance of HOLCUS LANATUS over other grasses (Remison and Snaydon 1978).

Palustrine Habitat(s): Bog/fen, SCRUB-SHRUB WETLAND
Terrestrial Habitat(s): Grassland/herbaceous, Urban/edificarian
Habitat Comments:

HOLCUS LANATUS exhibits a wide climatic tolerance of temperate regimes over a wide range of altitudes (0-1500m). It is killed by severe frost (Watt 1978b). Optimal growth occurs under moist conditions; however, it grows well in very wet conditions and can survive moderate periods of drought (Watt 1978a).

In Britain H. LANATUS occurs on a wide range of soil types including those of rich-fen and fen-meadow communities, poorly drained, waterlogged, low to moderately fertile, and nutrient-rich soils. It occurs independent of soil phosphorous content and grows well in potassium- and/or nitrogen-poor soils. It tolerates a wide range of soil pH, growing best between pH 5.0 and 7.5 (Thompson and Turkington 1988). Studies in Oregon (Hart and McGuire 1963) indicate an increase in the abundance of velvet grass under mildly acidic conditions.

Economic Attributes
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Economic Uses: FORAGE/BROWSE, Pasture
Management Summary
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Stewardship Overview: HOLCUS LANATUS is a perennial grass, native to Europe, that was brought into California as forage. It escaped from cultivation and has become a weed species, particularly in the California Coast Ranges. Velvet grass frequently occurs on poor, moist soils. It is a prolific seeder and can exist in the seed bank in large numbers. It can also reproduce from decumbent tillers. HOLCUS LANATUS is an aggressive weed and can become dominant if not controlled. The most effective control measure is physical removal by hand pulling or hoeing. Mowing or grazing used in combination with prescribed burning may also reduce the plant's dominance.
Restoration Potential: With the right combination of control measures, it should be possible to eliminate velvet grass from selected areas. Constant monitoring of previously infected sites will be necessary since it can quickly become dominant on a site.
Management Requirements: Control of velvet grass requires active management once it becomes established in an area.

MECHANICAL CONTROL

Hoeing or hand pulling HOLCUS LANATUS plants are effective, albeit time-consuming, control methods. Intensive mowing or grazing suppresses the establishment and spread of velvet grass on a site (Grime and Lloyd 1973). However, low intensity grazing may allow invasion of pastures (Thompson and Turkington 1988). Haggar and Elliot (1978) found that H. LANATUS increased from 18 to 43% of the total herbage over four years at a low stocking rate. The effects of grazing on velvet grass can be influenced by associated species and nutrient status (Thompson and Turkington 1988). HOLCUS LANATUS is also susceptible to damage from heavy treading by stock (Roberts 1982).

Control of the grass is most effective when it is cut prior to seed dispersal (Bakker et al. 1980). Elimination of the plant will be difficult, however, due to its perennial nature and ability to regenerate from decumbent tillers (Watt and Haggar 1980a) even when cut to only 2 cm above the ground surface (Anonymous 1976). The enormous HOLCUS LANATUS seed bank means that the grass can quickly re-establish itself after any disturbance, so careful monitoring is needed (Roberts 1982).

HOLCUS LANATUS is considered a "low-fertility species" (Scott and Hardacre 1974). Studies in Oregon (Hart and McGuire 1963) showed that nitrogen application reduced relative abundance. However, Haggar (1976) and Elliot et al. (1974) documented a positive response to nitrogen fertilization.

Lack of irrigation (Watt and Haggar 1980b), burning (Grime and Lloyd 1973), and ploughing (Beddows 1961) have reduced relative abundance of H. LANATUS in pastures.

PRESCRIBED BURNING

Burning has a deleterious effect on velvet grass under some condi- tions. It is particularly effective in controlling the grass when combined with grazing (Grime and Lloyd 1973).

BIOLOGICAL CONTROL

Very little research has been done on controlling HOLCUS LANATUS with insects or phytotoxins. Most insect predators of the weed also attack other, more desirable grass species (Charles Turner 1985). No list of insects preying on HOLCUS LANATUS exists for Canada (Thompson and Turkington 1988). However, Beddows (1961) has compiled one for British populations which includes various species of leafhoppers, butterflies, and flies.

HOLCUS species are hosts to the fungus GAEUMANNOMYCES GRAMINIS which also infects wheat and barley, so it is unlikely to be used to control HOLCUS (Roberts 1982). HOLCUS LANATUS is a host to the club-root disease PLASMODIOPHORA BRASSICAE which also infects several important vegetable crops (Webb 1949). Toms (1964) and Conners (1967) listed the following plant virus and fungus parasites from Canada: twist (DILOPHOSPORA ALOPECURI), leafsmut (ENTYLOMA DACTYLIDIS), crown rust (PUCCINEA CORONATA), rust (P. RECONDITA), stripesmut (USTILAGO STRIIFORMIS), EPICHLOE TYPHINA, and HELMINTHOSPORIUM TRISEPTUM. A list of fungi that infect velvet grass in Britain are compiled in Beddows (1961).

CHEMICAL CONTROL

HOLCUS LANATUS is susceptible to a variety of herbicides (Fryer and Makepeace 1978, Kirkham et al. 1982, and Watt 1983), but not all are safe or legal to use. Near streams or lakes, particular caution should be taken when using herbicides. Prior to using any herbicide, check with the County Agricultural Commissioner to determine which chemicals are legal to use in a given situation. The labels should also give more precise information on proper mixing and safety precautions. A certified Pest Control Applicator should be hired for large jobs or those requiring nonselective her- bicides.

Dr. Jim McHenry (1985) of the University of California, Davis, recommends the use of dalapon (Dowcon) to control HOLCUS LANATUS on California preserves. For perennials such as velvet grass, spraying should be done in spring when the seed head first appears. This results in better translocation of the herbicide into the root system. Dalapon will also kill other grasses and can kill some broadleaf species. It should be applied at a rate of 1 quart/100 gallons. Haggar and Elliot (1978) suggest biennial application of dalapon to control HOLCUS LANATUS. Dalapon is cleared for use on rights-of-way and for spot treatment of grazed areas. It is lethal to 50% of tested animals (LD50) at 9330 mg/kg of body weight but is classified as being of "relatively no hazard." The herbicide will persist in the soil for up to 8 weeks.

There are several petroleum oils used for weed control. The herbicidal use of oils depends on their chemical and physical properties. Most contact oils evaporate slowly and owe their plant toxicity to their high content of aromatic compounds. Spraying oil on HOLCUS LANATUS will be effective only if the entire plant is coated.

Herbicides can be applied uniformly over an area of large infesta- tions or by spot spraying individual plants. Dr. McHenry recommends using a flat-fan nozzle (Spraying Systems Co. #8003 or #8004 nozzle tip), rather than the cone nozzles available on most garden sprayers. Cone sprayers produce greater atomization of the chemicals and increase the chance of drift into unwanted areas. Spraying should be done on calm days to dry plants, as dew or rain will tend to dilute the herbicide reducing its effectiveness. When spraying large areas, a horizontal boom (6-8 feet long) made from aluminum tubing will improve herbicide coverage.

Monitoring Requirements: Monitoring is needed to determine the effectiveness of any velvet grass control measures. These will vary depending upon the degree of the problem on a given preserve.

Management Programs: HOLCUS LANATUS is present on the Northern California Coast Range Preserve (NCCRP). It is not a major problem species but is present along roads in wet portions of several of the meadows. Hand pulling of the plants and removal of the flowering heads has decreased the size of some of the infestations. Prescribed burning has not been used due to potential fire control problems.

Contact: Peter Steel, Caretaker NCCRP 42101 Wilderness Lodge Road Branscomb, CA 95417 (707) 984-6653

Monitoring Programs: Monitoring programs are ongoing at the following Oregon TNC preserves: Willow Creek, Cascade Head, Wren Prairie, and Camassia Plateau. For further information, contact:

Cathy Macdonald, Land Steward The Nature Conservancy Oregon Field Office 1205 25th Avenue Portland, OR 97210 (503) 228-9561

Management Research Needs: Much additional research is needed on obligate parasites and pathogens of HOLCUS LANATUS before any viable biocontrol measures can be developed. Prescribed burning is a relatively effective control technique in Europe, but more information should be obtained on its use as a control method.
Population/Occurrence Delineation Not yet assessed
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Population/Occurrence Viability
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U.S. Invasive Species Impact Rank (I-Rank)
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Disclaimer: While I-Rank information is available over NatureServe Explorer, NatureServe is not actively developing or maintaining these data. Species with I-RANKs do not represent a random sample of species exotic in the United States; available assessments may be biased toward those species with higher-than-average impact.

I-Rank: High/Medium
Rounded I-Rank: High
I-Rank Reasons Summary: Widespread in the U.S. Holcus lanatus is present in every state (including AK and HI), except WY, SD, NE, MN, and FL. Apparently, it causes more negative impacts in the western U.S. but more information is needed. Holcus lanatus forms dense swards that reduce native species richness and eliminate native grasses and forbs. Allelopathic activity is suspected. In Hawaii, it forms dense stands which shade out seedling establishment. Holcus lanatus occurs in disturbed areas but also in some communities of conservation significance. Holcus lanatus has become a major problem on western Oregon and Washington grassland preserves. Holcus lanatus was determined to be the fourth worst invasive plant threatening Garry oak and associated ecosystems in British Columbia; these communities occur from British Columbia south to California. In Hawaii, it is a common plant in a number of montane and subalpine communities, including wetlands and uplands. Elimination of the plant is difficult due to its perennial nature, its ability to regenerate from decumbent tillers even when cut to only 2 cm above the ground surface, and it enormous seed bank. More information is needed, especially about trends in distribution and abundance, and management difficulty.
Subrank I - Ecological Impact: High/Medium
Subrank II - Current Distribution/Abundance: High/Medium
Subrank III - Trend in Distribution/Abundance: High/Low
Subrank IV - Management Difficulty: High/Low
I-Rank Review Date: 13Feb2004
Evaluator: Tomaino, A.
Native anywhere in the U.S?
Native Range: Native to Europe, north Africa, and temperate Asia (Weber 2003).

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Screening Questions

S-1. Established outside cultivation as a non-native? YES
Comments: Established in the U.S. (Kartesz 1999).

S-2. Present in conservation areas or other native species habitat? Yes
Comments: An invasive exotic in natural areas in Hawaii and the western U.S. (Weber 2003).

Subrank I - Ecological Impact: High/Medium

1. Impact on Ecosystem Processes and System-wide Parameters:Medium/Low significance
Comments: Allelopathic activity is suspected (Watt 1978 in Smith 1998). Allelopathy may play a role in the dominance of Holcus lanatus over native grasses (Remison and Snaydon 1978 in Pitcher and Russo 1989). Presumeably, these effects are not irreversible.

2. Impact on Ecological Community Structure:Moderate significance
Comments: It forms dense stands which shade out seedling establishment in Hawaii (Smith 1998).

3. Impact on Ecological Community Composition:High/Moderate significance
Comments: It forms dense swards that reduce native species richness and eliminate native grasses and forbs (Weber 2003). Allelopathic activity is suspected (Watt 1978 in Smith 1998). Allelopathy may play a role in the dominance of Holcus lanatus over native grasses (Remison and Snaydon 1978 in Pitcher and Russo 1989). It is unpalatable to grazing animals (PIER 2003).

4. Impact on Individual Native Plant or Animal Species:High/Low significance
Comments: It seems it may disproportionately affect native grasses due to allelopathy. Allelopathy may play a role in the dominance of Holcus lanatus over native grasses (Remison and Snaydon 1978 in Pitcher and Russo 1989).

5. Conservation Significance of the Communities and Native Species Threatened:High/Moderate significance
Comments: Holcus lanatus has become a major problem on western Oregon and Washington TNC grassland preserves (Pitcher and Russo 1989). Presumeably these habitats are of conservation significance. Holcus lanatus was determined to be the fourth worst invasive plant threatening Garry oak and associated ecosystems in British Columbia (ESSA 2004). Garry oak ecosystems are rare and threatened in British Columbia (Garry Oak Meadow Preservation Society, not dated). Garry oak ecosystems range from southwestern British Columbia to California (Garry Oak Meadow Preservation Society, not dated). Holcus lanatus occurs in all ecoregions in northern California (Baldwin et al. 2004). Presumeably these communities are of conservation significance across their range and Holcus lanatus also threatens them in the U.S. In Hawaii, Holcus lanatus occurs in montane dry forest, montane mesic forest, montane wet shrubland, montane wet forest, subalpine dry shrubland, subalpine mesic grassland, and in a subalpine bog community (Wagner et al. 1999). Presumeably, these are of conservation significance.

Subrank II. Current Distribution and Abundance: High/Medium

6. Current Range Size in Nation:High significance
Comments: Widespread in the U.S.; present in every state except WY, SD, NE, MN, and FL (Kartesz 1999). Widely naturalized in Hawaii; it is established on Kauai, Oahu, Molokai, Maui, and Hawaii (Wagner et al. 1999). Also established in Alaska (Kartesz 1999).

7. Proportion of Current Range Where the Species is Negatively Impacting Biodiversity:Medium/Low significance
Comments: Classified as a wildland pest of lesser invasiveness by CALEPPC (1999); described as of concern in coastal grasslands and wetlands in northern California. It has become a weed species, particularly in the California Coast Ranges (Pitcher and Russo 1989). It is present on the Northern California Coast Range Preserve and occurs along roads in wet portions of several of the meadows; however, it is not considered a major problem there (Pitcher and Russo 1989). It is classified as most invasive, widespread in Oregon and Washington (WNPS 1997). Holcus lanatus has become a major problem in western Oregon and Washington TNC grassland preserves (Pitcher and Russo 1989). Classified as a pest of lesser threat by the Kentucky EPPC; principally in disturbed corridors, not readily invading natural areas (2000). Classified as moderately invasive in Virginia and described as occuring in all regions (VNPS and VDCR 2003). It is widely distributed in all but the most xeric habitats above 1300 m in Hawaii (Smith 1998).

8. Proportion of Nation's Biogeographic Units Invaded:High/Moderate significance
Comments: At most 96% of units, inferred from Kartesz (1999) and TNC (2001). At least 20% of units, inferred from Kartesz (1999) and TNC (2001).

9. Diversity of Habitats or Ecological Systems Invaded in Nation:High significance
Comments: In Hawaii, Holcus lanatus occurs in montane dry forest, montane mesic forest, montane wet shrubland, montane wet forest, subalpine dry shrubland, subalpine mesic grassland, and in a subalpine bog community (Wagner et al. 1999). In Nevada County, California it occurs in wetlands, riparian areas, wet meadows, and grasslands (Beedy and Brussard 2002). In the northeast U.S., it occurs in meadows (Gleason and Cronquist 1991). In western Oregon and Washington TNC grassland preserves, Holcus lanatus has become a major problem (Pitcher and Russo 1989). Presumeably, it occurs in Garry oak ecosystems (Garry Oak Meadow Preservation Society, not dated; EPPA 2004).

Subrank III. Trend in Distribution and Abundance: High/Low

10. Current Trend in Total Range within Nation:High/Low significance
Comments: It has recently expanded it range on Maui to West Maui (Wagner and Herbst 1999). It invades disturbed sites (Weber 2003). Disturbed sites are not declining, therefore it is assumed to not be declining.

11. Proportion of Potential Range Currently Occupied:Low significance
Comments: Approximately 80-90% of its potential range in the U.S. is currently occupied, inferred from USDA (1990) and Kartesz (1999).

12. Long-distance Dispersal Potential within Nation:High/Moderate significance
Comments: Seeds are dispersed by wind (Smith 1998). Propagules are likely to be dispersed unintentionally by humans (PIER 2003). Spikelets are 3-5 mm and usually 2 flowered (Beddows 1961).

13. Local Range Expansion or Change in Abundance:High/Low significance
Comments: It can quickly become dominant on a site (Pitcher and Russo 1989). It invades disturbed sites (Weber 2003). Disturbed sites are not declining, therefore it is assumed to not be declining.

14. Inherent Ability to Invade Conservation Areas and Other Native Species Habitats:Medium/Low significance
Comments: Holcus lanatus occurs in disturbed areas but also in some natural communities where perhaps disturbance is relatively minor. Holcus lanatus has become a major problem on western Oregon and Washington grassland preserves (Pitcher and Russo 1989). Holcus lanatus was determined to be the fourth worst invasive plant threatening Garry oak and associated ecosystems in British Columbia (ESSA 2004); these communities occur from British Columbia south to California (Garry Oak Meadow Preservation Society, not dated). In Hawaii, it is a common plant in a number of montane and subalpine communities, including wetlands and uplands. It invades disturbed sites in Hawaii rapidly (Smith 1998). Once disturbance is eliminated, Holcus lanatus may remain stable in a native grassland community (Jacobi 1981 in Smith 1998). This suggests it does not need repeated disturbance. In the northeast U.S., it is well established and occurs in meadows and roadsides in moist soil (Gleason and Cronquist 1991). In North Carolina and Virginia it is common and occurs in pastures, disturbed areas, roadsides, and hedge-rows (Weakley 2002), It is present on the Northern California Coast Range Preserve but it occurs along roads in wet portions of several of the meadows and is not a major problem there (Pitcher and Russo 1989).

15. Similar Habitats Invaded Elsewhere:High/Low significance
Comments: It is an alien species in New South Wales, Australia where it occurs in high altitude areas in the Mount Kosciuszko region (Johnston and Pickering 2001). This may or may not include at least one habitat it hasn't yet invaded in the U.S.

16. Reproductive Characteristics:High significance
Comments: Seeds are produced abundantly (Weber 2003). In England, seed production was found to be up to 240,000 seeds per plant (Watt 1976 in Pitcher and Russo 1989). In Russia, it was reported that up to 850 seeds were produced per plant (Trapaidze and Gogiya 1981 in Pitcher and Russo 1989). This is a rather large discrepancy but presumeably it produces over 1000 seeds per plant on average. It tolerates fires and regenerates rapidly from basal shoots (Smith 1998). It is not usually considered a stoloniferous species, but regeneration can occur by the formation of decumbent tillers in late summer that subsequently produce roots and shoots at the nodes; growth of these shoots may be enhanced by grazing or mowing (Pitcher and Russo 1989). It grows rapidly (Pitcher and Russo 1989). In Russia, it is reported to have an exceptionally long growing season (Trapaidze and Gogiya 1981 in Pitcher and Russo 1989). When its seeds were burried, only 3% were still viable after a year (Pitcher and Russo 1989). Self-fertilization occurs only occasionally and is impossible in some plants (Beddows 1931 in Pitcher and Russo 1989). It is a perennial herb (Weber 2003).

Subrank IV. General Management Difficulty: High/Low

17. General Management Difficulty:High/Moderate significance
Comments: Physical removal by hand pulling or hoeing is effective, although time-consuming (Pitcher and Russo 1989). Intensive mowing or grazing suppresses the establishment and spread of this grass (Weber 2003). A number of herbicides are effective (Pitcher and Russo 1989). Elimination of the plant is difficult due to its perennial nature, its ability to regenerate from decumbent tillers even when cut to only 2 cm above the ground surface, and it enormous seed bank (Pitcher and Russo 1989).

18. Minimum Time Commitment:High/Low significance
Comments: When its seeds were burried, only 3% were still viable after a year (Pitcher and Russo 1989). It is not known how long those 3% of seeds will remain viable. According to Pitcher and Russo (1989), it is possible to eliminate velvet grass from selected areas; however, constant monitoring will be necessary since it can quickly become dominant on a site. Elimination of the plant is difficult due to its perennial nature, its ability to regenerate from decumbent tillers even when cut to only 2 cm above the ground surface, and it enormous seed bank (Pitcher and Russo 1989). Apparently, control requires at least 2 years.

19. Impacts of Management on Native Species:Medium significance/Insignificant
Comments: Apparently, both physical and chemical methods are used. Some of the chemicals used to control this grass can kill other grasses and some broadleaf species, may be hazardous to animals, and may persist in the soil for up to 8 weeks (Pitcher and Russo 1989). Physical controls may be more effective (Pitcher and Russo 1989). Therefore, the only effective methods do not cause persistent reductions in native species.

20. Accessibility of Invaded Areas:Low significance/Insignificant
Comments: It occurs on TNC preserves in WA, OR, and CA where it is being managed (Pitcher and Russo 1989) so at least some sites are accessible. Also, it is unpalatable to grazing animals (PIER 2003), which suggests landowners would want to control it.
Authors/Contributors
Help
NatureServe Conservation Status Factors Edition Date: 21Nov1988
NatureServe Conservation Status Factors Author: DON PITCHER, MARY J. RUSSO (Revision), CAFO
Management Information Edition Date: 21Nov1988
Management Information Edition Author: DON PITCHER, MARY J. RUSSO (Revision), CAFO
Element Ecology & Life History Edition Date: 21Nov1988
Element Ecology & Life History Author(s): DON PITCHER, MARY J. RUSSO (Revision), CAFO

Botanical data developed by NatureServe and its network of natural heritage programs (see Local Programs), The North Carolina Botanical Garden, and other contributors and cooperators (see Sources).

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