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INVASIVE PLANTS ON THE MOVE CONTROLLING THEM IN NORTH AMERICA

Based on presentations at WEEDS ACROSS BORDERS

2006

CONFERENCE

Hermosillo, Sonora, Mexico, May 25 - 29, 2006

EOITEO BY

Thomas R. Van Devender Francisco J. Espinosa-García Bonnie L. Harper-Lore Tani Hubbard

T ABLE OF CONTENTS Preface Weeds Across Borders: A History ofWeed Awareness in North America Bonnie L. Harper-Lore Overview Cooperation among North American Countries Dealing with Weeds: Advances and Challenges Francisco J Espinosa-Garcia and Thomas R. Van Devender ATIO

AL STATUS O

INVASlVE

PLANTS AND

1 TERNATIO

Xl

XXI

AL

COOPERA TION

1

Canada: National Invasive Alien Plant Regulations and Initiatives Kenneth Allison

2

United States: Department of Agriculture's Animal & Plant Health Inspection Service Plant Importation Regulations and Initiatives Alan V Tasker

3

11

3

Mexico: The Need ofa National Weed Management Strategy Francisco J Espinosa-Garcia and Heike Vibrans

23

4

Mexico: Current Policy Responses to the Invasive Species Problem Laura Arriaga

33

5

Mexico: Biodiversity, Distribution, and Possible Impacts ofExotic Weeds Francisco J Espinosa-Garcia, José L. Villaseñor, and Heike Vibrans

43

6

The Americas: Invasive Species Information Management and Exchange The IABIN Invasives Information Network (I3N) Andrea Grosse, Silvia Ziller, and Elizabeth Sellers

1 7

8

VASIVE SPECIES ACCOUNTS

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AND FLORISTICS

British Columbia: Invasive Exotic Weeds on Federal Lands and Management Tools Raj Prasad, Jordon Brenner, and Satish Bundel Alberta: Weed Issues and Initiatives Shaffeek Ali

61

69

Vll

9

California: Floristic Composition of Roadside Grasslands inYo 10 County Ayzik Solomeshch, Sharon N Long, Michael G. Barbour, and Alison M Berry

77

10

Sonora: Non-native and Invasive Plants Thomas R. Van Devender, Richard S. Felger, Ana Lilia Reina-Guerrero, and J Jesús Sánchez-Escalante

85

11

Baja California Sur: Invasive Weeds José L. León de la Luz, M Dominguez-L; Thomas R. Van Devender

12

13

125 R. Dominguez-C;

Durango: Invasive Alien Plants M Socorro González-Elizondo, M González-Elizondo, Irma L. Lopez-Enriquez, and Jeffrey R. Bacon Querétaro: Invasive Weeds in Natural Semidesert Valentina Serrano-Cárdenas, P. Balderas-Aguilar,

and

137 J A. Tena-Flores,

157 and Ricardo Pelz-Marin

INVASIVE SPECIES, DISTURBANCE, AND LOCAL DIVERSITY

14

15

16

Increased Saltcedar (Tamarix) Seed Production and Regional Invasion from Large Reservoirs During Severe Droughts in the Northern Great Plains Derald G. Smith, and Cheryl M Pearce

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Binational Efforts to Control Invasive Species in Washington and British Columbia Sheilah Kennedy and Bob Parsons

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Non-native Plants and Vegetation and along the Río Grande in Urban Ciudad Juárez, Chihuahua Rafael Corral-Dlaz and Helvia Pelayo

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Weeds in Agricultural Crops in La Costa de Hermosillo, Sonora, Mexico Gerardo Martlnez-Dlaz and J Jiménez-Leon

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Weeds and Distrbed Habitats ofthe Cape Region ofBaja California Sur, Mexico Lucía Alfaro-Rodriguez and Laura Arriaga

V111

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Chapter 11 Baja California Sur: Native, Exotic, and Invasive Weeds José Luis León de la Luz', Miguel Dominguez-Leon',

and Thomas R. Van Devende/

'Herbario HCIB, Centro de Investigaciones Biológicas del Noroeste, CIBNOR, Apdo. Postal 128, La Paz, Baja California Sur 23000, MEX, email: [email protected]; 2Herbarium, Department ofPlant Sciences, PO Box 210036, Herring Hall, University of Arizona, Tucson, Arizona 85721-0036, USA Resumen Se presentan dos listados de especies de malezas, las sudcalifornianas nativas y las que han ingresado desde la colonización española, con énfasis en las que son invasoras. Las malezas sudcalifornianas suman 143 taxa de plantas vasculares; destacando la familia Poaceae (34 taxa), Asteraceae (16 taxa) y Fabaceae (14 taxa). Estas tres familias suman 64 taxa, representando el 45% de estas malezas. Ambientalistas en Baja California Sur están preocupados con introducidas-invasoras como Cryptostegia grandijlora, Tamarix aphylla, Convolvulus arvensis, Pennisetum ciliare y Acacia cochliacantha. Las malezas en general, en particular las nativas, tienen un importante papel eco lógico en la protección y regeneración del suelo ante disturbios diversos. En la entidad no existe legislación ambiental con respecto al ingreso de plantas exóticas. La flora de Baja California Sur, con solamente 0.3% especies exóticas, es una de las menos afectadas por este tipo de plantas en Norte América. Introduction Weeds are plant species that predominantly grow in places altered by human activities such as agricultural or cleared areas, roadsides, abandoned fields, vacant lots, and gardens, and are detrimental to man in some times and places (Lonsdale 1999, Williamson 1996), and can be native or non-native species. It is estimated that 1-5% of approximately 270,000 species of vascular plants on Earth are weeds (Rejmanek 1989, Sax 2001). In Mexico, weeds are classified as ruderales (roadside weeds) and arvenses (agricultural weeds), and invasiveness appears to be related to causing harrnful econornic or ecological damage (Villa señor and Espinosa-García 2004). In ecological terms, weed species usually have exponential growth, very high germination and survival rates, and major dernographic oscillations, tracking environrnental conditions. In the Lotka- Volterra logistic population growth curve, weeds are classified as "r-strategists", meaning that they are species independent frorn density and regulated by environrnental factors. Weeds have rapid vegetative growth including reproductive structures. Their habitats are ecological instable which causes high displacement (Rejmánek 1986). Mexico is one of the countries with the highest diversity of vascular plants, with an estimated 26,000 to 28,000 species (Mittermeier and Goettsch 1992). Weeds in the flora are often annual and perennial herbs, with fewer species with other life forms (shrubs, trees, etc.). Some weeds were introduced accidentally or on purpose at various times in a variety of ways, making it difficult to know their histories. Villaseñor and Espinosa-García (2004) reported 618 introduced species for Mexico (increased to 637 in Espinosa-García et al. this volume) with the grasses (28%), legumes (9%), and composites (9%) the most numerous groups. Considering that Baja California Sur has population of less than half a million, and one the best-preserved biotas

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in Mexico, we predict that native species dominate the weed flora, and that non-native and invasive species are at low levels. Here, we present analyses of the state weed flora through published information, herbarium specimens and databases, and our personal floristic research. Methods and Results Location and Climate: Baja California Sur is located in the southern half part ofthe arid Baja California Peninsula. The southern part of the state has a dry subtropical climate. To the north, the environment gradually changes into the Sonoran Desert, with hot surnmers, cold winter nights, and low rainfall. The climates on the coasts are different. Cold water in the Pacific Ocean causes morning fogs almost daily and relatively fresh and humid conditions on the coast. In contrast, the coasts of the Gulf of California are much drier and hotter most of the year, and with greater solar radiation. In general the climate for the state is classified as BW (very hot, very dry) and BS (hot, very dry). The average annual rainfall varies from 150 rnm on the coastal plains to 700 rnm in the mountains. Surnmer rains are dominant, with limited winter rainfall «10%). Mean annual temperature varies from 24°C to 18°C (García 1981). Soils in the southern half of the peninsula in desert and semi-desert areas are dominated by regosols; i.e., young, predominantly sandy soils, lacking significant horizons, low in organic matter, and high in some salts, especially calcium carbonate. Some mountain areas are dominated by rocky volcanic soils. Vegetation: Rzedowski's (1978) matorral xerófilo included a great variety desert and tropical, shrub-dominated vegetation types in arid and semiarid Mexican zones. In Baja California Sur, the semiarid tropical vegetation, which gradually mixes with the xerophytic vegetation of the Sonoran Desert, has been designed as matorral sarcocaule (sarcocaulescent desert, Anónimo" 1981), reflecting the abundance of plants with succulent trunks and branches (Shreve and Wiggins 1964, Wiggins 1980, Brown 1994). In Sonora, similar vegetation in the transition between tropical deciduous forest and Sonoran desertscrub is called thornscrub, with foothills thornscrub on rocky slopes and coastal thornscrub on the coastal plain of the Gulf of California (Martin et al. 1998). Physiognomic variants of matorral sarcocaule include crasicaule scrub, sarcocrasicaule scrub, log sarcocrasicaule scrub, microphyllous scrub, rosette desertscrub, sandy desertscrub, and other more local mezquitales (dominated by Prosopis), izotales (dominated by Yucca), and cardonales (dominated by Pachycereus) (Anónimo" 1981). Other vegetation types are formed by mangroves and halophytes along the coasts, and on sea cliffs and coastal dunes (Pérez-Navarro 1993). Tropical deciduous forest, oak woodland, and pine-oak forest are present in the Sierra de La Laguna, which reaches 2100 m elevation, in the southern part ofthe state are present (León de la Luz and Domínguez-C. 1989). Methods: Native weeds were part ofthe pre-Hispanic flora ofBCS, while the non-native exotic species began to arrive with the first missionaries beginning in the 1700s. A second consideration is the concept of 'invasiveness', which refers to non-native weeds that under certain conditions grow in dense population in natural habitats and can cause damage to human activities, and involve economic costs to control them. Weed species were identified using various sources. The Flora of Baja California (Wiggins 1980) was the primary reference with additional information from monographs by Gould and Moran (1981, Poaceae) and Daniel (1997, Acanthaceae). Weeds were also identified using collections and the database in Centro de Investigaciones Biológicas del Noroeste CIBNOR (HCIB) herbarium that hosts nearly 20,500 records of vascular plants, mostly BCS

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collections since 1990. This adds new species to Wiggins (1980) and documents the their presence in the state. Interviews with the staff ofthe Unión de Agricultores del Valle de Ciudad Constitución (farmers union) added species considered as agricultural weeds. In a few cases, decisions about whether species were weeds or non-native reflected our personal knowledge and experience with the flora. Results: Weeds were categorized as native or non-native to Baja California Sur. Table 1 presents a list of 81 native species of vascular plants that occur in naturally disturbed habitats or have the potential to be invasive under the right conditions or colonize open areas. The cornmon names used in the state are included. Table 2a shows a list of 58 non-native species founded in Baja California Sur. These species are locally cornmon either in natural areas, on roadsides, in urban vacant lots, or in fields or orchards in agricultural areas. Most of these species are not invasive and pose little threat to natural habitats; i.e. Mesembryanthemum crystallinum (hielito, ice plant; Figure 1). Table 2b shows four non-native species that have some economic uses and some management. Species accounts Five non-native plants represent serious threats to ecosystem stability, and are considered invasive exotic weeds in Baja California Sur. Acacia cochliacantha (Fabaceae): Guinolo (boatthorn acacia) is concentrated around the town of El Triunfo (23°52 'N, 1l0004'W) in BCS. It possibly arrived at the end of the 19th century when the mining industry was prospering in the area. Mining significantly disturbed the environment, especially by harvesting wood for timbers to support mine tunnels and firewood to fuel the smelting furnace (Cariño-Olvera 1996). This species is a natural dominant in thornscrub in Sinaloa and Sonora (Shreve 1937), is the primary secondary succession species in areas cleared in tropical deciduous forest in southern Sonora (Martín et al. 1998). The El Triunfo guinolos were probably derived from these mainland populations, reflecting the active traffic of persons and goods. Several invasive species deserve special attention. The advancement of Acacia cochliacantha in tropical deciduous forest has been slow since its known introduction in the last half of the 19th century. Its population is still concentrated in les s than 1000 ha, where it is the dominant, and has displaced species such as mauto (Lysiloma microphyllum) and palo zorrillo (Senna atomaria) and in the vegetation. Convolvulus arvensis (Convolvulaceae): Correhuela (field bindweed) is a very harmful agricultural weed causing enormous economic losses to farmers in Valle de Santo Domingo (near 25°08 'N, 111°50'W). It propagates through seeds and roots, which can penetrate several meters into the soil, and is transported as contamination in crop seeds. The most effective control method is to abandon the field for several years. It is estimated that 10,000 ha have been invaded by correhuela in this area. Cryptostegia grandijlora (Asclepiadaceae): Clavel de España (Pallay rubber vine) is a vine with large showy white-lavender flowers native to southern Asia. It is a very aggressive invasive with its fast growth and high regeneration and dispersion. CurrentIy it is invading streambeds and oasis in Sierra de la Giganta and the subtropical canyons in the Sierra de La Laguna, where it covers natural vegetation, including palm trees, stealing light and water (León de la Luz and Domínguez 2006). It was probably brought into BCS as an ornamental and escaped as it did in Alamos and other mining cornmunities in Sonora (Van Devender et al., this

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volume). Australia has invested important amounts of money to control it with few results (Australian Weeds Committee 2005). There are few efforts to control in BCS. Pennisetum ciliare (Poaceae): Zacate bufel (buffelgrass) was introduced in BCS in the late 1960's as forage for cattle. Although originally confmed to artificial grasslands, it escaped to other disturbed areas. Alfaro-Rodríguez and Arriaga (this volume) stressed disturbance by mining activities in the expansion of buffelgrass. Today it is mainly found along roadsides, but it is a potential threaten because it can disperse to natural vegetation as it has in Sonora (Lyons et al., this volume). Conservationists see it as a threat to natural vegetation because it occupies vital space and contends with natives for water and nutrients, while cattleman see it as an important forage resource. The disturbance caused by four hurricanes from 2001 to 2007 helped buffelgrass establish along roadsides and move into native vegetation mainly in southern subtropical area of the state. Tamarix aphylla. (Tamaricaceae): Pino salado (athel) is a tree introduced to BCS as a shade tree in urban areas in the 1920s. Around La Paz, it has escaped explosively into suburban areas in the last 15 years, and has successfully in disturbed areas, especially in cleared salty soils (Figure 2). These populations are reproducing by both seeds and root sprouting. In Sonora, similar invasions of T aphylla into disturbed roadside and riparian habitats have been observed in recent years in Sonora as well (Van Devender et al., this volume). Recently another species of pino salado (T chinensis Lour./T ramosissima Ledeb.) arrived in the San José del Cabo area of BCS (23°02 'N, 109°35'W), where is predicted to cause problems in the near future by displacing native riparian species in semi-permanent strearns habitats. Discussion Baja California Sur has the lowest population density of any state in Mexico. Currently its population is estimated in 450,000 inhabitants, with 90% in La Paz, San José del Cabo, and Constitución. Agriculture in BCS is confmed to an area of 30,000 ha in the Santo Domingo Valley, 13,000 ha near El Vizcaíno, and 10,000 ha in other areas (Anónimo" 2005). The entrance of non-native plant species to Baja California Sur began in the mission periodo Recently, truck freight traffic from California along the 1600 km of transpeninsular highway (MEX 1, fmished in 1972) and from port terminals at Santa Rosalía and La Paz has increased noticeably. Most of the traffic supplies goods and produce to the rapidly-growing populations in the Los Cabos area (estimated at 12%/year) and in La Paz (5%/year), both well above the national average (Anónimo" 2005). Also American seasonal residents and Mexican citizens are traveling in motor homes in greater numbers. The transport of non-native plant species are currently not controlled in the state. The 143 species identified as weeds in BCS represents a very low percentage (0.7%) of the estimated flora of more than 2000 species of vascular plants (Wiggins 1980, León de la Luz et al. 1999, Riemann and Ezcurra 2004). The families with the most weeds are Poaceae (21 native, 13 non-native), Asteraceae (lO native, 6 non-native) and Fabaceae (7 native and nonnative). These families contain 44% of the weeds, with 38 natives and 26 non-natives. As predicted, more BCS weeds were native species (56.6%, Table 1) than non-natives (43.4%, Table 2), a reflection that the flora is relatively intact. Only five non-native species are serious invasives that in some cases have economic costs to control them; four non-native species are under management (see above). Villaseñor and Espinosa-García (2004) reported that Eurasian and Neotropical elements are the main geographical sources of the 618 non-native species to Mexico We see similar geographic affmities for the non-native Baja California Sur weeds.

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More than 2000 species of plants have be en introduced in the United States (Vitousek }97), and at least 637 exotic species are known for Mexico (Espinosa-García. et al., this ilume). Stuckey and Barkley (1993) estimated that 18% ofthe California flora (6400 taxa) and Vo of the Arizona flora (3438 taxa) were non-native species. Wilson et al. (2002) report 233 m-natives for the Sonoran Desert (parts of Arizona, California, Sonora, Baja California, and aja California Sur), representing 11.6% of the estimated 2625 species in the Sonoran Desert 'elger 1990). In Baja California Sur, only 58 non-native species are reported for Baja California Sur, 3% of the state flora and 0.2% of the Mexican non-native species (Espinosa-G. et al., this ilume). In comparison, Sonora has 246 non-native species, 6.2% ofthe estimated 4,000 species . the flora (Van Devender et al., this volume.), and 38.6% of the Mexican non-native species ~spinosa-G. et al., this volume). Thus, Sonora with 2.5 times the are a ofBCS (74,000 km') has 2 times as many non-native species. Only five BCS non-natives (8.6%) are considered .vasive, compared to 37 species (15.0%) in Sonora (Van Devender et al. this volume). The ifferences probably reflect reduced winter rainfall, the greater isolation with limited cornrnercial affic with the United States and mainland Mexico, relatively limited agriculture, and relatively ,w human population. We conc1ude that Baja California Sur has one ofthe most intact floras in orth America. We predict that additional non-native species will be found in the Cabo San ucas, La Paz, and Santa Rosalía areas with further collections. We also predict the other 'idespread non-natives will arrive in the state as populations and cornrnerce increase . .cknowledgments Rayrnundo Dornínguez-Cadena from HCIB herbarium helped with information. Ing. R. oriano from the irrigation district in Cd. Constitución provided crop and weed data. Ana Lilia eina-Guerrero translated the paper into English. Iterature Cited .lfaro-Rodríguez, L., and L. Arriaga. 2009. Weeds and disturbed habitats ofthe Cape Region of Baja California Sur, México. Pp. in T. R. Van Devender, F. J. Espinosa-García, B. L. Harper-Lore, and T. Hubbard (eds.), Invasive Plants on the Move. Controlling them in North America. Proceedings of Weeds Across Borders 2006 Conference, Hermosillo, Sonora, May 25-28, 2006; Tucson, AZ. .nónimo", 1981. Carta de Uso del Suelo y Vegetación 1:100,000. Hoja La Paz. Secretaría de Programación y Presupuesto, Dirección General de Geografía del Territorio Nacional, México. .nónimo". 2005. Anuario Estadístico del Estado de Baja California Sur. Instituto Nacional de Estadística, Geografía e Informática- Gobierno del Estado de Baja California Sur. uistralian Weeds Cornrnittee. 2005. Weeds of National Significance. Rubber Vine. http://www.weeds.org.au/W oNS/ru bbervine/. Irown, D. E. (ed.). 1994. Biotic Cornrnunities: Southwestern United States and Northwestern Mexico. University ofUtah Press, Salt Lake City. .ariño-Olvera, M. M. 1996. Historia de las relaciones hombre-naturaleza en Baja California Sur 1500-1940. Universidad Autónoma de Baja California Sur, La Paz. )aniel, T. F. 1997. The Acanthaceae ofCalifornia y Peninsula ofBaja California. Proceedings of the California Academy ofSciences. 49:309-403.

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Espinosa-García, F. 1., 1. L. Villaseñor-R., and H. Vibrans. 2009. Mexico: Biodiversity, distribution, and possible impacts of exotic weeds. Pp. in T. R. Van Devender, F. 1. Espinosa-García, B. L. Harper-Lore, and T. Hubbard (eds.), Invasive Plants on the Move. Controlling them in North America. Proceedings of Weeds Across Borders 2006 Conference, Hermosillo, Sonora, May 25-28,2006; Tucson, AZ. Felger, R. S. 1990. Non-native plants of Organ Pipe Cactus National Monument, Arizona. Cooperative National Park Research Studies Unit, Tech. Rep. 31, Tucson, AZ. García, E. 1981. Modificaciones al Sistema de Clasificación Climática de Koppen para adaptarlo a las Condiciones de la República Mexicana. Instituto Geogr. Universidad Nacional Autónoma de México 2a. Ed. Gould, F. W., and R. Moran. 1981. The grasses ofBaja California, Mexico. San Diego Soco Nat. Hist., Memoir 12. Hickman, C. 1. (ed.). 1993. The lepson Manual: Higher Plants of California. University of California Press, Berkeley. León de la Luz, 1. L., and R. Domínguez-C .. 1989. Flora of the Sierra de la Laguna, Baja California Sur, Mexico. Madroño. 36:61-8l. León de la Luz, 1. L., and R. Dorninguez-C. 2006. Hydrophytes of the Sierra de la Giganta oases: Composition, structure, and conservation status. Jour. Arid Environ. 67:4:553-565. León de la Luz, 1. L., 1. 1. Pérez-Navarro, M. Domínguez-L:, and R. Domínguez-C. 1999. Flora de la Región del Cabo, Baja California Sur, México. Serie Listados Florísticos de México, Instituto de Biología Universidad Nacional Autónoma de México. Lonsdale, W. N. 1999. Global pattems of plant invasions and the concept of invasibility. Ecology 80: 1522-1536. Lyons, K. G., B. G. Maldonado-Leal, and G. Owen. 2009. Comrnunity and Ecosystem Comrnunity and Ecosystem Impacts of the non-indigenous C4 Buffelgrass (Pennisetum ciliare) in the Sonoran Desert, Sonora, Mexico. Pp. in T. R. Van Devender, F. 1. Espinosa-García, B. L. Harper-Lore, and T. Hubbard (eds.), Invasive Plants on the Move. Controlling them in North America. Proceedings of Weeds Across Borders 2006 Conference, Hermosillo, Sonora, May 25-28, 2006; Tucson, AZ. Martin, P. S., D. A. Yetman, M. Fishbein, P. lenkins, T. R. Van Devender, and R. K. Wilson (eds.). 1998. Gentry's Río Mayo Plants. The Tropical Deciduous Forest and Environs of Northwest Mexico. University of Arizona Press, Tucson. Mittermeier, R., and C. Goettsch 1992. La importancia de la diversidad bio lógica de México. Pp. 57-62 in México ante los Retos de la Biodiversidad. Conabio, México. Pérez-Navarro, 1. 1. 1995. La vegetación de ambientes costeros de la Región del Cabo, Baja California Sur: Aspectos florísticos y Ecológicos. Tesis de Licenciatura en Biología, UNAM-ENEP campus Iztacala. Rejmánek, M. 1996. A theory of seed plant invasiveness: the first sketch. Biological Conservation 78: 171-181. Rejmánek, M. 1989. Invasibility of plant comrnunities. Pp 369-405 in 1. A. Drake, H. A. Mooney, F. diCastri, R. H. Groves, F. 1. Kruger, M. Rejmánek, and M. Williamson. Biological Invasions: A Global Perspective. John Wiley & Sons, New York. Riemann, H., and E. Ezcurra. 2007. Endemic regions of the vascular flora of the peninsula of Baja California, Mexico. Jour, Veget. Sci. 18: 327-336.Rzedowski, 1. 1978. Vegetación de México. Ed. Lirnusa. México D.F.

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Sax, D. F. 2001. Latitudinal gradients and geographic range of exotic species: implications for biogeography. Jour. Biogeo. 28: 139-150. Shreve, F. 1937. Lowland vegetation ofSinaloa. Bull. Torrey Botanical Club 64:605-613. Shreve, F., and 1. L. Wiggins. 1964. Vegetation and Flora ofthe Sonoran Desert, 2 vols. Stanford University Press, Stanford, CA. Stuckey, R L., and T. M. Barkley. 1993. Weeds. Pp. 193-198 in Flora of North America Editorial Cornmittee (eds.) Flora ofNorth America. North ofMexico. Oxford University Press, New York and Oxford. Van Devender, T. R, R S. Felger, A. L. Reina-Guerrero, and 1. Jesús Sánchez-Escalante. 2009. Sonora: non-native and invasive plants. Pp. in T. R Van Devender, F. J. EspinosaGarcía, B. L. Harper-Lore, and T. Hubbard (eds.), Invasive Plants on the Move. Controlling them in North America. Proceedings of Weeds Across Borders 2006 Conference, Hermosillo, Sonora, May 25-28,2006; Tucson, AZ. Villaseñor,1. L., Y F. J. Espinosa-García. 2004. The alíen flowering plants ofMexico. Diversity and Distributions 10:113-123. Vitousek, P. M., C. M. D'Antonio, L. Loope-Lloyd, M. Rejmanek, and R. Westbrooks. 1997. Introduced species: A significant component of human-caused global change. New Zealand J. Ecol. 21: 1-16. Wiggins,1. L. 1980. Flora ofBaja California. Stanford University Press, Stanford, CA. Williamson, M. 1996. Biological Invasions. Chapman and Hall, London. Wilson, M. F., L. Leigh, and R S. Felger. 2002. Invasive exotic plants in the Sonoran Desert. Pp. 81-90 in B. Tellman (ed.) Invasive Exotic Species in the Sonoran Region. University of Arizona Press, Tucson.

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Figure 1. Hielitos/ice plant (Mesembryanthemum crystallinum) is a winter-spring annual, cornmon along roadsides and wastelands beween latitude 28° to 25°N. Photo by T. R. Van Devender.

A.

B.

Figure 2. A. Pino salado/athel (Tamarix aphylla) was frrst seen on a forrner salt flat in a neighborhood in La Paz during the early 1990s. Note new plants spreading away frorn larger one. No action has been taken to control the invasion. Photo J. L. León de la Luz. B. The leaves of T. aphylla are jointed and needle-like. Photo T. R. Van Devender.

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Table 1. Plant species native to Baja California Sur considered weeds under some conditions. Family

Species

Acanthaceae Aizoaceae Amaranthaceae Amaranthaceae Asteraceae Asteraceae Asteraceae Asteraceae Asteraceae Asteraceae Asteraceae Asteraceae

Elytraria imbricata (Vahl) Pers. Trianthema portulacastrum L. Amaranthus lepturus S.F. Blake Amaranthus palmeri S. Watson Ambrosia camphorata (Greene) Payne Ambrosia psilostachya De. Baccharis salicifolia (Ruiz & Pav.) Pers. Bidens bigelovii A. Gray Bidens laevis (L.) Britton, Sterns & Poggenb. Coreocarphus parthenioides Benth. Pectis rusbyi A. Gray Perityle aurea Rose

Asteraceae

Perityle californica Benth.

Asteraceae

Perityle crassifolia Brandegee

Bignoniaceae Boraginaceae Boraginaceae

Tecoma stans (L.) Juss. ex Kunth Cryptantha angustifolia (Torr.) Greene Heliotropium curassavicum L.

Brassicaceae Brassicaceae Caryophyllaceae Chenopodiaceae Convo lvulaceae Convo lvulaceae Cucurbitaceae Euphorbiaceae Euphorbiaceae Euphorbiaceae Fabaceae

Dryopetalon palmeri (S. Watson) O.E. Schultz Sibara pectinata (Greene) Greene Drymaria holeosteoides Benth. Atriplex barclayana (Benth.) D. Dietr. Cressa truxillensis HBK Evolvulus alsinioides L. Cucurbita cordata S. Watson Euphorbia polycarpa Benth. Euphorbia eriantha Benth. Jatropha cinerea (Ortega) Muell.-Arg. Chamaecrista 'nictitans (L.) Moench varo mensalis (Greenm.) H.S. Irwin & Barnaby Lupinus sparsijlorus Benth. varo insignitus C.P. Smith Pithecellobium dulce (Roxb.) Benth. Phaseolus filiformis Benth. Psorothamnus emoryi (A. Gray) Rydb. Senna obtusifolia (L.) Irwin et Barnaby Sphinctospermum constrictum (S. Watson) Rose Mentzelia adhaerens Benth. Abutilon incanum (Link) Sweet Horsfordia alata (S. Watson) A. Gray

Fabaceae Fabaceae Fabaceae Fabaceae Fabaceae Fabaceae Loasaceae Malvaceae Malvaceae

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Common ame Cardoncillo Verdolaguilla Quelite Quelite Hediondilla Hediondilla Guatamote Aceitilla blanca Aceitilla Aceitilla Manzanilla Manzanilla amarilla Manzanilla amarilla Manzanilla blanca Tronadora Hierba verruguera

Calabacita Golondrina Lomboi blanco

Alfalfilla Guamúchil Frijoli11o Cafecillo Pegarropa Malvilla

Malvaceae Malvaceae Malvaceae Malvaceae Malvaceae Martyniaceae

Sida glutinosa Cornmers ex Cavo Sida rhombifolia L. Sida xantii A. Gray Sphaeralcea coulteri (S. Watson) A. Gray Sphaeralcea hainesii Brandegee Proboscidea altheifolia (Benth.) Decne.

Molluginaceae N yctaginaceae N yctaginaceae N yctaginaceae N yctaginaceae Oxalidaceae Portulacaceae Rubiaceae Solanaceae Solanaceae Solanaceae Solanaceae Stercu liaceae Zygophyllaceae

Mollugo verticillata L. Allionia incarnata L. Boerhavia coccinea MilL Boerhavia erecta L. Boerhavia xantii S. Watson Oxalis corniculata L. Portulaca pilosa L. Diodia teres Walt. varo angustata A. Gray Physalis angulata L. Physalis glabra Benth. Physalis pubescens L. Datura discolor Bernh. Melochia tomentosa L. Fagonia californica Benth.

Cyperaceae Lemnaceae Poaceae

Cyperus dioicus LM. Johnst. Lemna minor L. Aristida adscensionis L.

Poaceae Poaceae Poaceae Poaceae Poaceae Poaceae Poaceae Poaceae Poaceae Poaceae Poaceae Poaceae Poaceae Poaceae

Brachiaria arizonica (Scribn. & Merr.) Blake Cenchrus echinatus L. Cenchrus palmeri Vasey Chloris brandegeei (Vasey) Swallen Bouteloua annua Swallen Bouteloua aristidoides (Kunth) Griseb. Bouteloua barbata Lag. var. barbata Brachiaria arizonica (Scribn. & Merr.) Blake Brachiariafasiculata (Sw.) L. Parodi Eragrostis orcuttiana Vasey Chloris chloridea (J. Presl.) Hitchc. Chloris virgata Swallen Leptochloa dubia (Kunth) Nees Leptochloafusca (L.) Kunth subsp. uninervia (J. PresL) N.W. Snow Leptochloa viscida (Scribn.) Beal Muhlenbergia microsperma (De.) Kunth Muhlenbergia texana Buckl. Oplismenus burmannii (Retz.) P. Beauv.

Poaceae Poaceae Poaceae Poaceae

134

Malva Espuela del diablo Anisillo Mochito Mochito Mochito Agrito Verdolaga Tomatillo Tomatillo Tomatillo Toloache Malva rosa

Zacate hormiguero Huachipore Huizapol

Zacate aceitilla Panizo Panizo

Poaceae Poaceae Poaceae

Panicum hirticaule J. Presl Phragmites communis Trin. Setaria liebmannii E. Fourn.

Carrizillo

Table 2a. Non-native species in Baja California Sur that behave as weeds under some conditions. Species

Family Aizoaceae Aizoaceae Apiaceae Apiaceae Asc1epiadaceae Asteraceae Asteraceae Asteraceae Asteraceae Asteraceae Asteraceae Brassicaceae Brassicaceae Brassicaceae Brassicaceae Brassicaceae Capparaceae Chenopodiaceae Chenopodiaceae Convo lvulaceae Cucurbitaceae Euphorbiaceae Fabaceae Fabaceae Fabaceae Fabaceae

Fabaceae Fabaceae Fabaceae Geraniaceae Lamiaceae

/ Mesembryanthemum crystallinum L. /Mesembryanthemum nodiflorum L. Anethum graveolens (L.) Dill Ciclospermum leptophyllum (Pers.) Sprague ex Britt. /Cryptostegia grandiflora (Roxb.) R. Br. Conyza bonariensis (L.) Cronquist / Lactuca serriola L. " Sonchus oleraceus L. /' Sonchus tenerrimus L. Verbesina encelioides (Cav.) Benth. & Hooker ex A. Gray varo encelioides Xanthium strumarium L. / Brassica rapa L. Capsella bursa-pastoris (L.) Medik Descurainia pinnata (Walt.) Britt. Nasturtium officinale R. Br. /' Sisymbrium irio L. Cleome viscosa L. /' Chenopodium murale L. ".Salsola tragus L. /Convolvulus arvensis L. ~ Cucumis dipsaceus Ehrenb. ex Spach. ,r

/ Ricinus communis L. /Acacia cochliacantha Humb. et Bonpl. ex Willd. /Acacia farnesiana (L.) Willd. Crotalaria pumila C.G. Ortega r Leucaena leucocephala (Lam.) deWitt. Mimosa biuncifera Benth. / Parkinsonia aculeata L. / Sesbania herbacea (MilI.) McVaugh / Erodium cicutarium (L.) L. Hér. ex Ait. I Leonotis nepetifolia (L.) R. Br.

135

Cornrnon Narne Hielitos Hielitos Apio silvestre Apio silvestre Clavel de España Humagón Lechuguilla Lechuguilla Lechuguilla Girasolillo Cadillo Quesillos Berro Matacandil Chuale Cardo ruso Correhuela Pepino silvestre Higuerilla Guinolo Vino rama Cascabelito Guaje Uña de gato Junco Cicuta Oreja de león

/Malva parviflora L. Argemone ochroleuca Sweet

Malvaceae Papavaraceae

Rumex pulcher L. Portulaca umbraticola Kunth / Anagallis arvensis L. Oligomeris linifolia (Vahl) lF. McBr. r Nicotiana glauca Graham

Polygonaceae Portulacaceae Primulaceae Resedaceae Solanaceae

¡'

Solanaceae Sterculiaceae Tamaricaceae Tamaricaceae Urticaceae Zygophyllaceae Zygophyllaceae

/,Physa/is nicandroides Schltdl. /' Waltheria indica L. rTamarix aphylla (L.) Karst. /Tamarix chinensis Lour. Parietaria floridana Small Tribulus cistoides L. ,/ Tribulus terrestris L.

Cyperaceae Cyperaceae Cyperaceae Liliaceae Poaceae Poaceae Poaceae Poaceae Poaceae Poaceae Poaceae Poaceae Poaceae Poaceae

Cyperus esculentus L. Cyperus odoratus L.