The Biology of Australian Weeds 25. Lantana Camara L
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Plant Protection Quarterly Vol.10(2) 1995 82 In weedy forms about half of the flow- The Biology of Australian Weeds ers usually produce a single-seeded fleshy spherical fruit 5–7 mm in diameter, 25. Lantana camara L. at first hard and green but ripening to purple or black and then consisting of a J.T. SwarbrickA, B.W. WillsonB and M.A. Hannan-JonesB. thin skin containing a purple pulp around A Weed Science Consultancy, 15 Katoomba Crescent, Toowoomba, the stony, pear-shaped, 3–4 mm diameter Queensland 4350, Australia. seed. The non-weedy forms set very few fruits. Each seed contains one or some- B Alan Fletcher Research Station, PO Box 36, Sherwood, Queensland 4075, times two embryos, and in the latter case Australia. both may germinate. The root system typically consists of a short tap root with laterals, which divide Name repeatedly to form a root mat. Lantana Lantana camara was known by at least tall but capable of becoming a liane up to does not sucker from damaged or broken five polynomial descriptive names, start- 15 m tall if given support (Figure 1). roots, but will regrow vigorously from the ing with Lantana, Viburnum and The arching, scrambling or prostrate base of the stem and more slowly from Periclymenum, before Linnaeus gave it its stems are initially 4-angled but become rooted horizontal stems in contact with binomial name in 1753. He retained cylindrical and up to 15 cm thick with moist soil. Lantana (origin obscure) and described a age. Young stems are hairy and in the number of species including camara (a weedy forms carry sharp recurved prick- Variation within the species West Indian name) and aculeata (prickly), les along the angles, whilst those of the Lantana is an aggregate species, derived a species now included within the non-weedy forms are rounder, more slen- through horticultural and natural hy- L. camara complex (L. camara sensu lato). der and without prickles. bridization, selection and somatic muta- Linnaeus’ L. camara was non-prickly The opposite pairs of ovate leaves oc- tion from a number of similar and prob- whilst his L. aculeata was prickly; both cur on 1–3 cm long petioles. Each leaf is ably closely related (though spatially were described from European garden 3–10 cm long and 2–6 cm wide, with a separated) tropical American species. material (Schauer 1851). bluntly pointed, rounded or heart-shaped This has resulted in many hundreds of Lantana has become the common name base, finely toothed margin and bluntly forms, which are also referred to as for the most abundant and complex spe- pointed tip. The leaves are rough and cultivars and varieties (Howard 1969). cies within the genus. It contains several finely hairy on both surfaces and strongly The forms vary in ploidy, bush shape, hundred wild and cultivated forms. veined below, and have a strong charac- flower colour, prickliness, response to the teristic smell when crushed. The upper environment and natural enemies, and Description epidermis carries very few stomata. Both chemical composition, including toxicity Lantana is a brittle, much branched, the stomata and the trichomes from both to animals. At least 29 forms have become thicket-forming shrub, normally 2–4 m surfaces of leaves have been related to tax- naturalized in eastern Australia (Smith onomy (Raghavan and Arora and Smith 1982) and probably others in 1960, Shah and Mathew 1982). the Northern Territory and Western Aus- Inflorescences develop in the tralia. A number of non-weedy forms are axils of young leaves. They are sold by nurseries. Smith and Smith (1982) compact, flat to dome-shaped considered that 19 forms were sufficiently and 2–3 cm across and each is common in eastern Australia to be eco- supported by a finely hairy nomically important as either weeds or 2–8 cm long peduncle with a poisonous plants. club-shaped tip. Each inflores- The basic chromosome number of cence contains 20–40 sessile Lantana is 11, with 12 being the basic flowers, each subtended by a number for the rest of the genus stiff deciduous bract. The (Raghavan and Arora 1960). Diploid, flower buds are angular and triploid, tetraploid, pentaploid and tightly packed, and open from hexaploid forms of lantana have been re- the outside of the inflorescence ported in South Africa (Stirton 1977, Spies towards the centre. Each and Stirton 1982, Spies 1984), and triploid, flower has a 9–12 mm long tetraploid and pentaploid lantanas in In- tube and four unequal rounded dia (Sen and Sahni 1955). Raghavan and petals 4–8 mm across. Newly Arora (1962) showed that Indian diploids opened flowers normally have were small, stunted and very rare and yellow throats, and the petals that the weedy forms were mostly vary from white to cream, yel- tetraploids with some triploids. Koshoo low, pink, orange, red or pur- and Mahal (1967) claimed that the breed- ple. After pollination flowers ing system combines sexual, semisexual darken, lose the yellow centre and asexual (apomictic) systems, and and fall, except in non-weedy Stirton (1977) stated that polyploidy has forms which mostly fail to set developed through both auto- and allo- seed and retain their flowers polyploidy. longer. Pollen grains are al- Most of the weedy forms of lantana in most globular, tricolpate and South Africa and India and probably Aus- 30–35 µm across and are finely tralia appear to be tetraploids, whilst most Figure 1. Lantana (Lantana camara L.) (Line textured (d’Almeida and of the non-weedy ornamental forms ap- drawing by Dr. G. Scott). Roland-Heydacker 1985). pear to be triploids. 83 Plant Protection Quarterly Vol.10(2) 1995 After growing many weedy forms of larger bushes, longer internodes and leaf Adelaide (Bailey 1841), and was followed lantana together in South Africa to study blades, prickly stems and high levels of by many others. The plant was quickly their cytology and the morphology of fruit production, whereas most of the or- spread northwards along the coast, with their inflorescences, bracts and flowers, namental forms produced smaller the first Australian collections of appar- Spies (1984) concluded that ‘plants on dif- bushes, had shorter internodes and ently naturalized lantanas from the Bris- ferent ploidy levels are morphologically leaves, lacked prickles, and while produc- bane River in 1861 and near Sydney in similar’. A similar study of Indian plants ing similar numbers of flowers, set very 1862 (Swarbrick 1985). By 1897 lantana by Natarajan and Ahuja (1957) showed few fruit. The ornamental form ‘Drap d’or’ was described as being ‘a huge rambling that non-prickly forms occurred at 2n, 3n occupied an anomalous position since it shrub and a most troublesome weed and 4n levels, flower colour varied within showed the large bush size, long which has spread to an alarming extent, all ploidy levels, and all ploidy levels con- internodes and large leaves of the weedy and forms impenetrable thickets on the tained forms with both nil and good seed group but the lack of prickles and low banks of streams, deserted farms and the set. seed production of the ornamental group, edges of scrubs’ in the Brisbane area and Tandon and Bali (1955) compared dip- suggesting significant differences in its as being ‘equally abundant about Port loid and triploid forms and found that the derivation from both other ornamental Jackson’ (Bailey 1897). Lantana appears to latter was more vigorous, had larger and and weedy forms. have been grown in Western Australia by darker leaves, produced more and larger 1875 (Swarbrick 1985) but may have only flowers and, unlike the diploid, was largely History spread to the Northern Territory during sterile. Raghavan and Arora (1960) found Lantana was probably first introduced or since the Second World War (I.L. Miller no correlations between flower colour or into Europe about 1640 from Brazil personal communication). Further expan- lower leaf epidermal patterns and five (Howard 1969), where both prickly and sion into previously unoccupied areas is levels of ploidy. non-prickly taxa are considered to be na- probably still occurring, often assisted by Swarbrick (unpublished) compared the tive, common and widespread (Schauer land clearing or other human disturbance morphology of seven weedy forms from 1851). Introductions continued through- (Humphries and Stanton 1992). Smith’s collection at the CSIRO in Bris- out the 17th, 18th and 19th centuries bane (now destroyed) and six ornamental (Swarbrick 1985) resulting in an aggre- Geographical distribution forms from commercial nurseries under gate species of mixed parentage (Howard uniform conditions in south-eastern 1969, Stirton 1977). Lantana became a fa- Australia Queensland. He studied bush volume, vourite hothouse plant in Europe in the Lantana is widely distributed throughout average length of the third internode from late 19th century, with 397 new varietal coastal and subcoastal areas from the shoot tip, average length of fourth names being added to nurserymen’s cata- Ulladulla in New South Wales to Cape node leaves, average number of prickles logues between 1850 and 1900 (Howard Melville in Queensland, with very scat- per 5 cm of angle on the third internode 1969). Many of these forms would have tered infestations in the Northern Terri- and average number of flowers and fruits been distributed to the colonies, including tory, Western and South Australia (Figure per inflorescence. Analysis of results Australia. 2). It is also present as a weed on both showed that the weedy forms were all The first Australian record of lantana Lord Howe and Norfolk Islands very similar and were characterized by was in 1841 at the old Botanic Gardens in (Swarbrick 1985). Outside Australia Lantana is widely grown as an ornamen- tal shrub throughout the tropics, subtrop- ics and warm temperate zones.