Malvastrum americanum (L.) Torr., Malvaceae

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Present on Pacific Islands?  yes

Primarily a threat at high elevations?  no

Other Latin names:  Malva americana L.; Malva spicata L.; Malvastrum spicatum (L.) A. Gray

Common name(s): [more details]

Chinese: sui hua sai kui

English: Indian Valley false mallow, bastard sida-retusa, false mallow, mulberry-mallow, spiked false mallow, spiked malvastrum, spiked-mallow, wild mulberry

French: mauve d'Amérique

Spanish: malva loca, malva silvestre

Habit:  herb

Description:  "Perennial herbs or subshrubs up to 2 (-3) m tall, densely pubescent, the hairs principally stellate, (5) 6-12-armed, and simple.  Leaf blades ovate, 2-8 (-14.5) cm long, sometimes obscurely 3-lobed, margins crenate-dentate, apex acute to acuminate, base subcordate.  Flowers in dense terminal spikes up to 10 (-18) cm long, or sometimes solitary, each one subtended by a bifid bract up to 5 (-6) mm long; involucral bracts lanceolate, (4-) 5-7 (-9) mm long, adnate basally to calyx, hispid with simple or bifurcate hairs; calyx 5-6 mm long at anthesis, up to 10 mm long in fruit; corolla yellowish orange, rotate, 12-17 mm in diameter; staminal column 2-3 mm long, stelluate pubescent.  Schizocarp reddish brown, (4-) 5-6 mm in diameter, mericarps (9) 10-15 (-18), 1.5-2 mm high, 1.5-2.5 (-3) mm wide, unarmed or sometimes with an obscure ventro-apical mucro and dorso-lateral ribs, dehiscent basally and baso-dorsally, endoglossum usually present.  Seeds 1.3-1.7 mm long"  (Wagner et al., 1999; p. 894).

Habitat/ecology:  In Hawai‘i, "reportedly naturalized and locally common in boulder-strewn grass and shrubland, ca. 5 m, at Kaloko (Queen's Beach), O‘ahu" (Wagner et al., 1999; p. 894).

"Plants observed by the author appear to be short-lived shrubs that grow yearly without dieback. The species is reported also growing as an herb (annual) and subshrub (dieing back to permanent woody parts each year) (Howard 1989, Stevens and others 2001). Indian Valley false mallow is usually not eaten by cattle or other herbivores. Moderate grazing coupled with fire tends to make the species more abundant. It also grows in areas disturbed by river overflows, farming, road building, and land clearing. The species is intolerant of shade and severe competition. It disappears under closed tree canopies or in dense tall grass swards. However, Indian Valley false mallow does grow under a broken tree canopy. It grows on most types of well-drained soil. Mean annual rainfall in Puerto Rican habitat ranges from about 750 to 1000 mm (author's observation). It is known from near sea level to 1000 m in elevation in Nicaragua (Stevens and others 2001)"  (Wildland shrubs of the United States and its territories).

Propagation:  Seed.  "No specialized means of dispersal is apparent; the seeds are small and undoubtedly are moved to some extent by wind, water, and animals"  (Wildland shrubs of the United States and its territories).

Native range:  New World tropics and subtropics; exact native range obscure; naturalized elsewhere (GRIN).

Presence:

Pacific
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
Ecuador (Galápagos Islands) San Cristóbal Group	San Cristóbal Island	introduced invasive	Charles Darwin Foundation (2008)
Ecuador (Galápagos Islands) Santa Cruz Group	Santa Cruz Island	introduced invasive	Charles Darwin Foundation (2008)
State of Hawaii Hawaiian Islands	Moloka‘i Island	introduced invasive	Starr, Forest/Starr, Kim/Loope, Lloyd (2008) (p. 47) Voucher cited: Starr, Starr & Naeole 050519-02 (BISH)
State of Hawaii Hawaiian Islands	O‘ahu Island	introduced invasive	Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (p. 894) Voucher cited: K. Nagata 3245 (BH, HLA)

Pacific Rim
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
Australia Australia (continental)	New South Wales	introduced invasive	National Herbarium of New South Wales (2013) Naturalised
Australia Australia (continental)	Australia (continental)	introduced invasive	National Herbarium of New South Wales (2013) South Australia, Victoria, Western Australia Naturalised
Australia Australia (continental)	Northern Territory	introduced invasive	National Herbarium of New South Wales (2013) Naturalised
Australia Australia (continental)	Queensland	introduced invasive	National Herbarium of New South Wales (2013) Naturalised
Central America Central America (Pacific rim)	Costa Rica (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
Central America Central America (Pacific rim)	El Salvador (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
Central America Central America (Pacific rim)	Guatemala (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
Central America Central America (Pacific rim)	Honduras (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
Central America Central America (Pacific rim)	Nicaragua (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
Central America Central America (Pacific rim)	Panama (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
China China	China (People's Republic of)	introduced invasive	Zhengyi, Wu/Raven, Peter H./Deyuan, Hong (2013) Weed of semi-arid areas. Fujian
Indonesia Indonesia	Indonesia (Republic of)	introduced invasive	U.S. Dept. Agr., Agr. Res. Serv. (2013) Naturalized
Mexico Mexico	Mexico (United Mexican States)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
South America (Pacific rim) South America (Pacific rim)	Colombia	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
South America (Pacific rim) South America (Pacific rim)	Ecuador (Republic of) (continental)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
South America (Pacific rim) South America (Pacific rim)	Perú (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
Taiwan Taiwan Island	Taiwan Island	introduced invasive	Zhengyi, Wu/Raven, Peter H./Deyuan, Hong (2013) Weed of semi-arid areas.

Also reported from
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
United States (continental except west coast) United States (other states)	United States (other states)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013) Texas
United States (continental except west coast) United States (other states)	USA (Florida)	native	Francis, John K., ed. (2009)

Control:  If you know of control methods for Malvastrum americanum, please let us know.