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.

Common name(s): [more details]

Chinese: sui hua sai kui

English: false mallow, Indian Valley false mallow, spiked malvastrum

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:  "A pantropical weed occurring from near sea level to over 2,000 m" (Wagner et al., 1999; p. 894).

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)	Australia (continental)	native	U.S. Dept. Agr., Agr. Res. Serv. (2011)
China China	China (People's Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2011)
Colombia Colombia	Colombia (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2011)
Costa Rica Costa Rica	Costa Rica (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2011)
Ecuador (Mainland) Ecuador	Ecuador (Republic of) (continental)	native	U.S. Dept. Agr., Agr. Res. Serv. (2011)
El Salvador El Salvador	El Salvador (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2011)
Guatemala Guatemala	Guatemala (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2011)
Honduras Honduras	Honduras (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2011)
Indonesia Indonesia	Indonesia (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2011)
Mexico Mexico	Mexico (United Mexican States)	native	U.S. Dept. Agr., Agr. Res. Serv. (2011)
Nicaragua Nicaragua	Nicaragua (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2011)
Panama Panama	Panama (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2011)
Perú Perú	Perú (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2011)

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)	USA (Florida)	native	Francis, John K., ed. (2009)

Additional information:
Fact sheet from "Wildland shrubs of the United States and its territories: thamnic descriptions" (PDF format).

Additional online information about Malvastrum americanum is available from the Hawaiian Ecosystems at Risk project (HEAR).

Information about Malvastrum americanum as a weed (worldwide references) may be available from the Global Compendium of Weeds (GCW).

Taxonomic information about Malvastrum americanum may be available from the Germplasm Resources Information Network (GRIN).

References:

Charles Darwin Foundation. 2008. Database inventory of introduced plant species in the rural and urban zones of Galapagos. Charles Darwin Foundation, Galapagos, Ecuador.

Charles Darwin Research Station. 2005. CDRS Herbarium records.

Francis, John K., ed. 2009. Wildland Shrubs of the United States and its Territories: Thamnic Descriptions General Technical Report IITF-WB-1 U.S. Department of Agriculture, Forest Service International Institute of Tropical Forestry and Shrub Sciences Laboratory (online resource).

Starr, Forest/Starr, Kim/Loope, Lloyd. 2008. New plant records from the Hawaiian Archipelago. In: Evenhuis, Neal L. and Eldredge, Lucias G., eds. Records of the Hawaii Biological Survey for 2007. Bishop Museum Occasional Papers 100:44-49.

U.S. Dept. Agr., Agr. Res. Serv. 2011. National Genetic Resources Program. Germplasm Resources Information Network (GRIN). Online searchable database.

U.S. Dept. Agr., Nat. Res. Cons. Serv. 2011. The PLANTS Database. National Plant Data Center, Baton Rouge, LA 70874-4490 USA.

Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. 1999. Manual of the flowering plants of Hawaii. Revised edition. Bernice P. Bishop Museum special publication. University of Hawai‘i Press/Bishop Museum Press, Honolulu. 1919 pp. (two volumes).

Wiggins, I. L./Porter, D. M. 1971. Flora of the Galapágos Islands. Stanford University Press. 998 pp.

Zhengyi, Wu/Raven, Peter H./Deyuan, Hong. 2011. Flora of China (online resource).