Journal of the Department of Agriculture, Western Australia, Series 4

Volume 9 Number 3 1968 Article 6

1-1-1968

Common heliotrope : (Heliotropum europaeum L.)

G R W Meadly

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Recommended Citation Meadly, G R W (1968) "Common heliotrope : (Heliotropum europaeum L.)," Journal of the Department of Agriculture, Western Australia, Series 4: Vol. 9 : No. 3 , Article 6. Available at: https://researchlibrary.agric.wa.gov.au/journal_agriculture4/vol9/iss3/6

This article is brought to you for free and open access by Research Library. It has been accepted for inclusion in Journal of the Department of Agriculture, Western Australia, Series 4 by an authorized administrator of Research Library. For more information, please contact [email protected], [email protected], [email protected]. COMMON HELIOTROPE

(Heliotropium europaeum L)

G. R. W. MEADLY, M.Sc, Officer-in-Charge, Weeds and Seeds Branch

THE Borage family, to which common heliotrope belongs, includes several other plants which are troublesome weeds in Australia. Patersons curse is widespread in several States, yellow burr-weed is a problem in wheat growing areas, particularly in Victoria, and corn gromwell also causes concern to some wheat farmers.

Although there are a number of native species of Heliotropium, common helio­ The Agriculture Protection Board trope (H. europaeum) was introduced, declared common heliotrope a primary probably from the Mediterranean region. noxious weed in February, 1967, after It thrives in low rainfall areas, persist­ a large infestation found at Bodallin ing under drought conditions with an in 1966 indicated that this could prove annual rainfall as low as eight inches, and an aggressive weed in Western Aus­ now infests wide areas of south-eastern tralia. The weed has also been re­ Australia. It frequently encroaches on corded in the Metropolitan area and in native grassland after perennial grasses scattered localities in the agricultural have been replaced by winter annuals due districts, extending into the pastoral to overstocking. Summer fallows where areas. moisture is conserved are often badly Heliotrope can cause heavy stock infested. losses in areas where it becomes estab­ In Western Australia, heliotrope has lished. been recorded from the Metropolitan Area and scattered localties in the agri­ cultural districts extending into the pas­ The stalked, oval-shaped leaves borne toral areas. alternately along the stems are grey- In 1966 a large infestation was located green in colour, somewhat darker above at Bodallin, indicating that it could prove than below. The stems and leaves are an aggressive weed. Bearing in mind the clothed with course, white hairs. severe stock losses experienced in areas The numerous small white flowers are where it has become established, it was arranged in a long, slender, curved spike. declared a primary noxious weed by the The calyx is divided almost to the base Agriculture Protection Board in February, while the short, tubular five-lobed corolla 1967. is usually swollen below the middle with rounded and spreading lobes. Each flower Description produces four small nutlets. Common heliotrope is an erect annual Common heliotrope is favoured by warm with a strong rooting system, and grows conditions and germination frequently to a height of about one foot. occurs after summer rains. 121

Journal of Agriculture, Vol 9 No 3 1968 COMMON HELIOTROPE (Heliotropium europaeum) A.—Habit B.—Leaf. C.—Portion of inflorescence. D.—Flower. E.—Ovary and style. F.—Carpels (nuts). B. to F.- variously enlarged 122

Journal of Agriculture, Vol 9 No 3 1968 Common Heliotrope (Heliotropium europaeum L.) Although other species occur naturally, common heliotrope is an introduction, prob­ ably from the Mediterranean region. It contains toxic alkaloids and has been re­ sponsible for heavy losses of stock in New South Wales, Victoria and South Australia.

123 Journal of Agriculture, Vol 9 No 3 1968 Significance In 1960 an outbreak of Heliotropium Common heliotrope reduces the carry­ poisoning occurred among cattle in the ing capacity of pastures, but its toxic Riverina district of New South Wales; properties are of greater significance. both steers and heifers were affected. Heavy losses of sheep have occurred in There are indications that cattle react the main infested areas of New South much more rapidly than sheep. Wales, Victoria and South Australia due to direct poisoning by toxic alkaloids which Control cause liver damage and, indirectly, chronic Common heliotrope is typically a copper poisoning associated with an in­ summer-growing annual and its incidence creased release of copper by injured liver is largely controlled by summer rains. cells. Dormant seeds in the soil will remain in Losses are usually low or not evident a viable condition for a number of years. during the first year that sheep are As mentioned above, this weed tends to exposed to common heliotrope but heavy invade areas from which perennial grasses losses, often exceeding 50 per cent., have have disappeared because of overgrazing. occurred during the second season of Management is therefore an important grazing. control factor where such grasses occur or British breeds and crossbreds are more can be established. likely to be affected than Merinos as they are less discriminating in their grazing. Isolated plants can be handled by pulling Experience in South Australia has shown or hoeing before seeds have matured. that heliotrope is particularly dangerous Cultivation to prevent seed formation is in stubble paddocks, where it often pro­ also an effective control measure but is vides a green bite amongst otherwise dry often undesirable or impracticable during herbage. The risk is reduced by feeding the summer period. a hay or grain supplement as the stubble Common heliotrope is not readily feed declines. There is no known cure, destroyed by chemicals, 2,4-D at 2 lb. acid the liver becoming permanently damaged. equivalent per acre of ester or amine, has The owner of the Bodallin property where proved effective against young plants but the weed occurs has experienced sheep resistance increases with larger plants and losses which he attributes to common results become less reliable. Trials with heliotrope. chemicals are being continued.

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