Review Site Pairs Along the Twigs, and Isolated Unpruned Plants Form Dense Rounded Canopies

122 Plant Protection Quarterly Vol.14(4) 1999 during winter, but only in the coldest dis- tricts. The stems of all species are erect, with thin greyish bark and prominent lenticels. The entire leaves occur in oppo- Review site pairs along the twigs, and isolated unpruned plants form dense rounded canopies. The small flowers occur in dense masses at the ends of terminal and lateral twigs, and consist of a short (0.5–1.0 mm) The Biology of Australian Weeds. 36. Ligustrum tubular four lobed calyx, a white to cream corolla tube of similar length ending in lucidum Aiton and Ligustrum sinense Lour. four spreading lobes 2–4 mm long, two small white (mauve to purple in L. sinense) J.T. SwarbrickA, S.M. TimminsB and K.M. BullenC spreading stamens, and a central ovary A Weed Science Consultancy, 15 Katoomba Crescent, Toowoomba, containing several loculi surmounted by a short columnar style. The flowers of Queensland 4350, Australia. B all species of privet have distinct and to Department of Conservation, PO Box 10-420, Wellington, New Zealand. many people unpleasant odours based on C University of Queensland, Gatton, Queensland 4343, Australia. trimethylamines (Mabberley 1997). The fruits are ovoid or spherical dark blue to black berries with a very thin skin, oily Name and related Australian south-eastern Australia and New Zealand fleshy pulp, woody or papery endocarp species and L. ovalifolium is at least occasionally and 1–3 seeds. The European privet (Ligustrum vulgare L.) naturalized in parts of New Zealand, nei- was apparently known as ligustrum about ther is a significant environmental weed. Key to Ligustrum species naturalized in 2000 years ago by Virgil (Gledhill 1985). Australia and New Zealand (after The name may have meant ‘binder’ with Description Goulding 1973) reference to some use of the rather flexible Ligustrum species are deciduous, semi- a Young shoots and branchlets without twigs, and was retained for the whole ge- deciduous or more commonly evergreen hairs; leaves glossy above, pointed; nus by Linnaeus. The English common shrubs and trees. Under warm moist con- flowers shortly stalked or stalkless; co- name privet appears to be obscurely de- ditions all species retain their foliage rolla lobes reflexed b rived from the 16th century English name throughout the year, although in Aus- Young shoots and branchlets hairy; primprimp for the same plant (Brown tralia both L. sinense and L. lucidum may leaves not glossy above, often bluntly 1993). Apart from this single European partially defoliate during dry weather. tipped; flowers stalked; corolla lobes species the genus ranges from India to In New Zealand they tend to defoliate spreading, not reflexed c north-eastern Australia, with most species in south-eastern and eastern Asia (Kiew 1978, Mabberley 1997). The endemic Aus- tralian species L. australianum F.Muell. is found in rainforest margins throughout sub-coastal central and north-eastern Queensland, whilst the south-eastern Asian L. glomeratum Blume occurs natu- rally in rainforests on Christmas Island (Green 1993). About 12 species of Ligustrum are in cultivation throughout the world as orna- mental or hedge plants, at least four of which have become naturalized in Aus- tralia and New Zealand. L. vulgare L. (Eu- ropean or common privet) occurs across much of Europe and northern Africa, from whence it has been introduced into Aus- tralasia. Both L. lucidum Aiton (broad- leaved or tree privet) and L. sinense Lour. (Chinese privet) were introduced indi- rectly from eastern Asia via Europe as ornamentals. The Japanese species Ligustrum ovalifolium Hassk. probably ar- rived in this region by the same route and for the same purpose. Ligustrum lucidum and L. sinense are widely naturalized throughout sub- coastal eastern Australia and the North Is- land of New Zealand, in both of which they are more or less serious environmental weeds. Both species are sparsely naturalized in the South Island of New Zea- land. Although L. vulgare is naturalized in Figure 1. Ligustrum lucidum – broad-leaved privet. Plant Protection Quarterly Vol.14(4) 1999 123 Ligustrum sinense (Figure 2) (Dellow 1983, Hnatiuk 1990, Carr et al. is usually a multi-stemmed 1992, Queensland Herbarium 1997). It also shrub 2–6 m tall. Canopies are naturalized on Norfolk Island (Flora of rounded and are composed of Australia 1984). thin mid to dark green non- Ligustrum sinense (Figure 4) is also natu- shiny leaves which are 3–5 cm ralized in sub-coastal eastern Australia long, with rounded to bluntly from northern Queensland to Victoria pointed tips and tapering bases. (Hnatiuk 1990, Carr et al. 1992, Queens- The leaves are finely hairy land Herbarium 1997). It is a potentially when young and are similarly serious environmental weed on both Nor- coloured above and below. The folk and Lord Howe Islands (Flora of Aus- flowers occur in dense tapering tralia 1984). masses about 10 cm long at the The Australian distribution of both spe- ends of lateral and terminal cies probably reflects both their spread in twigs, and are followed by cultivation and their climatic tolerances. shortly stalked 5 mm long Both species are expected to spread fur- blackish-purple berries. ther in the future. Ligustrum vulgare is a single to multi-stemmed shrub 3–4 m New Zealand tall. Unpruned canopies are Ligustrum lucidum is widely naturalized in rounded and consist of thick the North Island of New Zealand, espe- shiny leaves 3–6 cm long. The cially in Northland, Auckland, Waikato, leaves have bluntly pointed tips the Bay of Plenty and Coromandel. It oc- and tapering bases and are curs in waste places, forest margins, open finely hairy when young. The forests and coastal cliffs, and can invade flowers occur in dense masses closed forests wherever gaps occur. Its 3–6 cm long at the ends of the height and longevity mean that once es- twigs, and are followed by tablished it can dominate the native veg- shortly stalked glossy blackish etation (Cameron 1990). 6–8 mm long berries. Ligustrum sinense is abundantly natu- Ligustrum ovalifolium is a ralized on roadsides and cliffs in and 3–5 m tall shrub. It resembles around towns in the North Island, particu- broad-leaved privet in having larly in the north and west, where it com- Figure 2. Ligustrum sinense – Chinese privet. hairless young twigs and petes with shrubby native plants. It also glossy leaves, but the leaves are occurs around Nelson, Christchurch and b Leaves 5–13 cm long; corolla tube only 3–6 cm long, the flower tube is twice Jackson in the South Island (Webb et al. shorter or as long as the lobes; anthers as long as the petals and the blackish ber- 1988, Williams and Karl 1996)). exserted from tube; fruits bluish-black, ries are stalkless. on short smooth stalks L. lucidum Habitat Leaves 3–6 cm long; corolla tube more Variation Climatic requirements than twice as long as lobes; anthers Variegated forms of L. lucidum and L. Both L. lucidum and L. sinense grow best barely exserted from tube; fruits black, sinense are common in cultivation. Vari- where there is moderate to high soil mois- stalkless L. ovalifolium egation ranges from white through yellow ture and air humidity throughout the c Lower leaf midribs finely hairy, mar- to pinkish and may be either marginal or year, e.g. in sheltered gullies on slopes and gins smooth to wavy; corolla tube blotchy across the leaves (Griffiths 1994). tablelands which receive higher than av- shorter than lobes; anthers mauve to Variegation is most prominent in well-lit erage local rainfall or runoff. In these situ- purple, exserted; fruits blackish-pur- leaves, tends to disappear in heavily ations they generally grow vigorously and ple, on hairy stalks L. sinense shaded parts of the canopy, and has not retain their leaves throughout the year, Lower leaf midribs not finely hairy, been observed in naturalized plants. whilst in more exposed areas with lower margins never wavy; corolla tube humidities their growth is usually more slightly longer than lobes; anthers History stunted and they tend to defoliate during white, barely exserted; fruits glossy Ligustrum lucidum was collected by Euro- dry seasons. black, on short slightly hairy stalks pean horticulturists in China in 1794 and L. vulgare L. sinense in 1852 (Chittenden 1951), both Substratum Ligustrum lucidum (Figure 1) is a small to probably from cultivated plants. They Ligustrum lucidum and L. sinense grow on medium sized tree, generally with a sin- were widely cultivated in Europe before a very wide variety of soils, ranging from gle trunk 3–15 m tall. Trees growing in the being brought to Australia and New Zea- sands through loams to nearly pure clays open have dense pyramidal crowns of land during the nineteenth century and (Westoby et al. 1983). L. lucidum grows rigid dark green shiny leaves 5–13 cm planted as hedges and shade trees. Nei- well in limestone karst around Molong in long with pointed tips and rounded bases, ther species appears to have become natu- central New South Wales. In the Sydney which are hairless when young and are ralized in New Zealand until the 1950s area L. lucidum prefers soils that are higher distinctly paler below than above; mature (Esler 1987). in clay content, whilst L. sinense prefers leaves snap when folded backward across more sandy soils, though both grow best the midrib. The flowers occur in dense ta- Distribution in areas of increased nutrition due to ur- pering masses up to 20 cm long at the tips Australia ban runoff, soil disturbance and removal of the twigs. The corolla tubes are much Ligustrum lucidum (Figure 3) is widely of the native vegetation (Adamson 1977, the same length as the petals, and are fol- naturalized in sub-coastal eastern Aus- Buchanan 1989).

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