Buddleja davidii Franch., Scrophulariaceae

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Present on Pacific Islands?  yes

Primarily a threat at high elevations?  yes

Risk assessment results: 

Accept, score: -4 (Go to the risk assessment (Australia))
High risk, score: 13 (Go to the risk assessment (Pacific))

Other Latin names:  Buddleia davidii Franch.; Buddleja variabilis Hemsl.

Common name(s): [more details]

Chinese: da ye zui yu cao

English: buddleia, butterfly bush, orange eye, summer lilac

French: arbre aux papillons, lilas d'été

Habit:  shrub

Description:  "Shrubs 0.5-5 m tall; young branchlets, leaves abaxially, petioles, and inflorescences white tomentose or pubescent with stellate hairs. Branchlets nearly 4-angled. Stipules often present, suborbicular to ovate, 1-6 mm. Petiole 1-5 mm; leaf blade narrowly ovate, narrowly elliptic, or very narrowly ovate, 4-20 x 0.3-7.5 cm, adaxially dark green and glabrous or subglabrous, base cuneate, margin serrate, apex acuminate, lateral veins 9-14 pairs. Inflorescences terminal, seemingly racemose or thyrsoid cymes, 4-30 x 2-5 cm; lower bracts leaflike, others small and linear. Calyx campanulate, 2-3.5 mm, outside stellate pubescent to glabrous; lobes narrowly triangular, 0.5-2 mm. Corolla violet to dark purple, sometimes white, with an orange-yellow throat, 0.8-1.4 cm, outside glabrous or stellate pubescent and/or with glandular hairs; tube narrowly cylindrical or subcylindrical, 6-11.5 x 1-1.5 mm, inside pilose except at base; lobes suborbicular, 1.5-3 x 1.5-3 mm, outside glabrous. Stamens inserted at middle to near base of corolla tube; anthers oblong, 0.8-1.2 mm. Ovary ovoid, 1.2-2 x 0.8-1.1 mm, glabrous to minutely pubescent, sometimes with glandular hairs. Style 0.5-1.5 mm; stigma clavate. Capsules brown, narrowly ellipsoid to narrowly ovoid, 5-9 x 1.5-2 mm, glabrous or sparsely stellate pubescent. Seeds ellipsoid, 2-4 x ca. 0.5 mm, long winged at both ends"  (Flora of China online).

"Shrub 1-3 m high, the fragrant flowers with lilac corollas orange-yellow in throat" (Smith, 1991; p. 74).  "Deciduous (occasionally semi-evergreen) open, multi-stemmed shrub to 3+ m tall. Stems are bluntly angled, clad in tufts of easily-removed soft woolly hair (downy hairs when young), and become lax when long. Thin, willow-shaped leaves (6-20 x 3-8 cm) are usually hairless above, white or hairy grey underneath, and finely toothed. Distinctive, dense, cone-shaped hanging clusters (30 x 5 cm) made up of many fragrant purple or white flowers (5 mm diameter) with orange insides are produced from December to February and are followed by seed capsules (5-10 mm long)"  (Weedbusters New Zealand).

Habitat/ecology:  Colonizes disturbed areas such as roadsides and riparian areas (Randall et al., 1996).  "Buddleia can grow almost anywhere, but prefers nutrient-rich watercourses and creeklines, where it quickly dominates, shading out and replacing native plant species"  (Weeds of Blue Mountains bushland).  In the Pacific, it could be a potential problem at higher elevations.  In Hawai‘i, naturalized in moist and wet open areas at 3000-5000 ft. elevation. 

In New Zealand, "has invaded streambeds, roadsides and land slips.  ...It appears to be a pioneer species and is eventually replaced by native species if disturbance is not continuous." In Australia, "riparian communities also support infestations, particularly in association with disturbance in the urban area." (Csurhes & Edwards, 1998; p. 145). In New Zealand, "riverbanks, roadsides and disturbed sites, particularly around forested areas, waste places in and around settled areas. Buddleia or butterfly bush is abundantly naturalised to the point of being a nuisance in some areas. It has spread deep into the Urewera and other remoter parts of the North Island, and tolerates a wide range of soil conditions, even growing on the almost raw lava of Rangitoto Island" (Webb et al., 1988; p. 449).

Propagation:  Wind-dispersed seeds. "Prolific numbers of small brown cylindrical fruits are produced in late summer, each tailed to aid dispersal. Seeds are mainly dispersed by wind and water, but also by machinery, vehicles, the movement of soil, and by dumping" (Weeds of Blue Mountains bushland).

Native range:  Tibet and central China, cultivated elsewhere.

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) Santa Cruz Group	Santa Cruz Island	introduced cultivated	Charles Darwin Foundation (2008)
Fiji Fiji Islands	Viti Levu Island	introduced cultivated	Smith, Albert C. (1991) (p. 74) Voucher cited: DA 16089
State of Hawaii Hawaiian Islands	Kaua‘i Island	introduced invasive cultivated	Herbst, Derral R./Wagner, Warren L. (1996) (p. 13) Voucher cited: Lorence & Flynn 7452 (US) Sparingly naturalized.
State of Hawaii Hawaiian Islands	Maui Island	introduced invasive	Starr, Forest/Starr, Kim/Loope, Lloyd L. (2003) (p. 26) East Maui. Voucher cited: Starr & Martz 000831-9 (BISH)
New Caledonia New Caledonia Archipelago	Île Grande Terre	introduced cultivated	MacKee, H. S. (1994) (p. 94) Vouchers cited: Baumann 6798, MacKee 12298
Papua New Guinea Papua New Guinea (eastern New Guinea Island)	Papua New Guinea (eastern New Guinea Island)	introduced invasive cultivated	Conn, Barry J., ed. (1995) (pp. 129-131) A garden escape.

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	Harley, Barbara (2009)
Australia Australia (continental)	Australia (continental)	introduced invasive cultivated	Csurhes, S./Edwards, R. (1998) (p. 145)
British Columbia (province of Canada) Province of British Columbia	Canada (British Columbia)	introduced	U.S. Dept. Agr., Nat. Res. Cons. Serv. (2013)
China China	China (People's Republic of)	native	Zhengyi, Wu/Raven, Peter H./Deyuan, Hong (2013) Thickets on mountain slopes, side of draws in mountains; 800-3000 m. Gansu, Guangdong, Guangxi, Guizhou, Hubei, Hunan, Jiangsu, Jiangxi, Shaanxi, Sichuan, Xizang, Yunnan, Zhejiang.
China China	Hong Kong	introduced cultivated	Wu, Te-lin (2001) (p. 241)
Japan Japan	Japan	introduced	Mito, Toshikazu/Uesugi, Tetsuro (2004) (p. 188)
Malaysia Malaysia	Malaysia (country of)	introduced invasive cultivated	Conn, Barry J., ed. (1995) (pp. 129-131) A garden escape.
New Zealand New Zealand	New Zealand (country)	introduced invasive	Webb, C. J./Sykes, W. R./Garnock-Jones, P. J. (1988) (p. 448)
Singapore Singapore	Singapore (Republic of)	introduced cultivated	Chong, Kwek Yan/Tan, Hugh T. W./Corlett, Richard T. (2009) (p. 20) Cultivated only
United States (west coast) United States (west coast states)	USA (Oregon)	introduced	U.S. Dept. Agr., Nat. Res. Cons. Serv. (2013)
United States (west coast) United States (west coast states)	USA (California)	introduced	U.S. Dept. Agr., Nat. Res. Cons. Serv. (2013)
United States (west coast) United States (west coast states)	USA (Washington)	introduced	U.S. Dept. Agr., Nat. Res. Cons. 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)	United States (other states)	introduced	U.S. Dept. Agr., Nat. Res. Cons. Serv. (2013)

Comments:  A major problem weed in New Zealand (Csurhes & Edwards, 1998; p. 145).

See also B. asiatica and B.madagascariensis.

Control:  Seed bank reinfests bared sites. Cut stumps resprout.  Difficult to prevent reinvasion. Follow up 6-monthly. Maintain rolling front.

Physical:  Pull or dig small plants. Leave on site to rot down.

Chemical:  1. Cut stump application: apply glyphosate (250ml/L) or Tordon Brushkiller (250ml/L) to horizontally cut stumps.
2. Bore and fill: drill holes sloping into the sapwood at regular intervals around the tree.  Place a mixture of glyphosate (250ml/L) or undiluted Tordon Brushkiller into each hole.
3. Frilling: with a sharp chisel or axe, make a deep cut into the sapwood at regular intervals around the base of the tree ensuring the plant is not ring-barked.   Immediately apply a mixture of glyphosate (250ml/L) or undiluted Tordon Brushkiller to the cuts using a paintbrush or squeeze bottle.
4. Weed wipe (February-April): glyphosate (333ml/L).
5. Spray (February-April): glyphosate (10ml/L) or metsulfuron-methyl 600g/kg (5g/10L) or Tordon Brushkiller (90ml/15l (knapsack) or 250ml/100L (spraygun))"  (Weedbusters New Zealand).