Hawkweeds: State Prohibited Weed (DPI Vic)

Home , Hieracium, Pilosella, Pilosella aurantiaca

June 2003 Hawkweeds: State Prohibited Weed LC0376 Keith Turnbull Research Institute, Frankston ISSN 1329-833X

This Landcare Note describes Hieracium spp., hawkweeds, as State Prohibited Weeds in Victoria. Common name Hawkweeds Scientific name Hieracium spp. Family Asteraceae (daisies) Status Hieracium species are proclaimed as a State Prohibited Weed in Victoria. This means that Hieracium spp. are to be eradicated if possible from the State. Hieracium species are also proclaimed weeds in New South Wales, Western Australia and Tasmania and have been classified as prohibited imports by the Australian Quarantine and Inspection Service. There are between 700 and 1000 world species of Hieracium, mostly native to the Northern Hemisphere in temperate and montane areas, but with some species in South America and southern Africa. No species are native to Australia. Orange hawkweed Hieracium aurantiacum, native to Europe, is the only species known to have become naturalised in Victoria. Small infestations are known from Falls Creek and Mt Hotham. Other hawkweed species have been available from nurseries and markets and are likely to be present in gardens. Description Herbs with milky sap, often hairy, with a basal rosette of leaves. The group is divided into two subgenera: Pilosella, which contains perennial, stoloniferous, often mat-forming species that reproduce sexually, and Hieracium, which contains annual, non-stoloniferous species, that reproduce asexually by seed and produce little pollen. Commonly each species is highly variable and contains several subspecies. Hybrids occur frequently. Stems – erect, the creeping stolons root readily at the nodes, like a strawberry plant. Leaves – in a basal rosette or alternate on the stems, entire or toothed, rarely lobed, often hairy.

Figures 1 and 2. Orange hawkweed, Hieracium aurantiacum.

Flowers – small, many combined together into cylindrical to Zealand, in upland pastures in North America, and in Japan bell-shaped heads (as in other daisies). Like dandelions, the and Patagonia. flower heads have only petal-bearing ligulate (ray) florets and They tolerate poor soils, thrive in overgrazed areas and are lack non-petal bearing tubular or disc florets (eg. as seen in the difficult to control. In native grasslands they can occupy the centre of the sunflower head). Usually yellow but sometimes entire space between existing tussocks and may subsequently white, orange or red. Bracts surrounding the flower head are of displace the grasses themselves. uneven length, in 1-3 rows; the receptacle (basal part of the Hawkweeds are closely related to dandelions and sow thistles flower on which the florets are attached) flat and naked; heads and release chemicals that inhibit the growth of other plants. arranged in corymbs or panicles or occasionally solitary. Hawkweeds grow from wind-dispersed seeds to form very Seeds – an achene, cylindrical with a truncate apex, 10-15 dense patches, which spread by lateral growth of stolons and ribbed, bearing a pappus (parachute) of 1-2 rows of brownish daughter plants. or whitish, fragile bristles. Spread from garden specimens, dumping of garden waste and Roots – fibrous; stout rhizomes present in some species. mail order seeds are likely sources of new hawkweed H. aurantiacum L. (Pilosella aurantiaca), orange hawkweed. infestations. Stoloniferous, 15-40 cm high, with long, spreading hairs; Predictions based on climatic requirements and land leaves mostly in a basal rosette, stalkless, lance-shaped, up to characteristics indicate that at least H. aurantiacum and H. 15 cm long and 2.5 cm wide, with a wide, pale central vein, ramosissimum and other species with similar properties and sometimes with slightly toothed margins and with very biology such as H. pratense, H. x floribundum and H. conspicuous simple 1-4 mm long hairs on both surfaces, green; piloselloides could be highly invasive in Victoria. stolons slender, hairy; flowers December to March, heads orange, about 15 mm, bracts black-tipped and with glandular Management hairs, inflorescence commonly of 5 to 10 or more heads in a The Department of Primary Industries is responsible for the tight cluster at the top of the stem; flowering stems erect, hairy, control of State Prohibited Weeds. Please provide details of usually leafless, sometimes with up to four small leaves near any occurrences of Hieracium spp. to a Catchment the base; seeds dark brown or purplish black, up to 2 mm long Management Officer at a local office of the Department. with dingy white, non-feathery pappus hairs up to 6 mm long. Manual and chemical control measures will be used on Weed in New Zealand and North America. infestations. H. caespitosum Dumort., field hawkweed. Leaves 5-20 cm long, elongated at base, with long hairs; stems 30-50 cm high, References with 1-3 leaves, bearing 3-50 flower heads, flowers yellow. Blood, K. (2001) Environmental Weeds – A Field Guide for SE H. lepidulum (Stenstr.) Omang, tussock hawkweed. Australia. Mt Waverley, C.H.Jerram Science Publishers. H. pilosella L. (Pilosella officinarum), mouse-ear hawkweed. Groves, R. (1996) Hawkweeds. Australian Quarantine and Stoloniferous, mat-forming, usually with many long, slender, Inspection Service, Pest Leaflet. leafy stolons; to 30 cm high; leaves mostly in a basal rosette, Morgan, J. (2000) Orange hawkweed Hieracium aurantiacum L.: a oblong or oblanceolate to spoon-shaped, to 12 cm long, entire, new naturalised species in alpine Australia. Victorian Naturalist bristly, with long pale hairs and a dense matt of star-shaped 117(2), 50-51. hairs on the underside when young; flowers heads to 25 mm Roy, B., Popay, I., Champion, P., James, T. and Rahman, A. (1998) diameter, usually solitary, bracts around the flower head hairy, An Illustrated Guide to Common Weeds of New Zealand. Canterbury, flowers pale yellow, often with a red stripe; seeds purplish- NZ, New Zealand Plant Protection Society. black. Weed in North America and Europe. The worst species Sell, P.D. and West, C. (1976) Hieracium L. Pp. 358-410 in T.G. in New Zealand. A potential alpine invader in Australia. Tutin et al. (Eds.) Flora Europaea Volume 4. Plantaginaceae to Compositae (and Rubiaceae). London, Cambridge University Press. H. praealtum Vill. ex Gochnat, king-devil hawkweed. Webb, C.J., Sykes, W.R. & Garnock-Jones, P.J. (1988) Flora of New Generally a mat-forming perennial, 15-45 cm high; with Zealand Volume IV. Naturalised Pteridophytes, Gymnosperms, slender, leafy stolons; leaves mostly basal, lance-shaped, 10-15 Dicotyledons. Christchurch NZ, DSIR. cm long, bluish-green on the upper surface with 3 mm long hairs; flowers yellow, heads to 20 mm diameter, on stems up Acknowledgements to 30 cm high, few to many (up to 25) heads per stem, up to 3 small leaves per stem. Compiled by Ian Faithfull. Figures 1 and 2 by Kate Blood, copyright 2001 CRC for Weed Management Systems. Properties Hawkweeds are potentially extremely serious weeds, This publication may be of assistance to you but the State of Victoria and its officers do not guarantee that the publication is without flaw of any particularly for the tussock grasslands of the tablelands of kind or is wholly appropriate for your particular purposes and therefore south-eastern Australia. They are major environmental and disclaims all liability for any error, loss or other consequence which may pasture weeds in montane and subalpine areas in New arise from you relying on any information in this publication.