Richardia scabra L., Rubiaceae

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Present on Pacific Islands?  yes

Primarily a threat at high elevations?  no

Risk assessment results:  Reject, score: 8 (Go to the risk assessment).

Other Latin names:  Richardsonia scabra (L.) A. St.-Hil.

Common name(s): [more details]

English: rough Mexican clover

Habit:  herb

Description:  "The root is a taproot and the stem is branched, erect, fleshy, very hairy and 20 to 50 centimeters tall.  The leaves are also pubescent and are sessile, opposite, entire, oblong or elliptical to lanceolate or ovate, 2 to 4 centimeters long and 1 to 1.5 centimeters wide.  The inflorescence is a white flower-head subtended by four leaf bracts, two longer than the others.  The flowers are perfect and occur in terminal clusters.  The calyx is a small whorl consisting of 5 to 6 pointed lobes.  The fruit is a capsule divided into 3 to 4 parts and produces flat, obovate seeds"  (Cardenas et al., 1972; p. 265).

"Richardia brasiliensis has mericarps that are adaxially broadly and openly concave with a slim median keel, whereas those of Richardia scabra are adaxially closed to a narrow groove or sulcus.  These 2 species are otherwise similar in morphology"  (Lorence et al., 1995; pp. 50-51).

Habitat/ecology:  "Annual herb common in cultivated fields, perennial crops, waste areas, roadsides and ditchbanks"  (Cardenas et al., 1972; p. 265).

Propagation:  Seed (Cardenas et al., 1972; p. 265).

Native range:  United States, Mexico, Central and South America (GRIN).

Presence:

Pacific
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
State of Hawaii Hawaiian Islands	Hawai‘i (Big) Island	introduced invasive	Pratt, Linda W./Bio, Leali‘i F. (2012) (p. 79) Voucher cited: L.W. Pratt 3556 (BISH)
State of Hawaii Hawaiian Islands	Kaua‘i Island	introduced invasive	Lorence, David H./Flynn, Timothy W./Wagner, Warren L. (1995) (pp. 50-51) Vouchers cited: M. Kiehn & T. Flynn MK-900920-1/1 (PTBG, US, WU), M. Kiehn & T.Flynn MK-900917-2/1 (PTBG, WU), T. Flynn 1245 (PTBG)
State of Hawaii Hawaiian Islands	Maui Island	introduced invasive	Oppenheimer, Hank L. (2003) (p. 23) West Maui. Voucher cited: Oppenheimer H100045 (BISH)
State of Hawaii Hawaiian Islands	Maui Island	introduced invasive	Imada, Clyde T./James, Shelly A./Kennedy, Barbara H. (2008) (p. 14) Vouchers cited: East Maui: W. L. Wagner & S. Mill 4739 (BISH), F. Starr & K. Martz 010726-3 (BISH). West Maui: H. Oppenheimer H30706 (BISH)
State of Hawaii Hawaiian Islands	Moloka‘i Island	introduced invasive	Imada, Clyde T./James, Shelly A./Kennedy, Barbara H. (2008) (p. 14) Voucher cited: Oppenheimer H40404 (BISH, PTBG)
State of Hawaii Hawaiian Islands	O‘ahu Island	introduced invasive	Imada, Clyde T./James, Shelly A./Kennedy, Barbara H. (2008) (p. 14) Voucher cited: C. Imada & L. Crago 2004-27 (BISH)

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)		Holm, Leroy/Pancho, Juan V./Herberger, James P./Plucknett, Donald L. (1979) (p. 309)
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	Hong Kong	introduced invasive	Wu, Te-lin (2001) (p. 270) On grassland or in wasteland.
Japan Japan	Japan	introduced	Mito, Toshikazu/Uesugi, Tetsuro (2004) (p. 187)
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)

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	U.S. Dept. Agr., Agr. Res. Serv. (2013)

Control:  If you know of control methods for Richardia scabra, please let us know.