Helminthotheca echioides
(bristly oxtongue)

Helminthotheca echioides, commonly known as bristly oxtongue, is an annual or perennial, herbaceous herb found in dry and disturbed areas. Native to the western Mediterranean region and possibly elsewhere in Europe and Asia, it has been introduced to North America, South America, South Africa, Australia, New Zealand and other parts of Europe. H. echioides can be a weed of crops and can form dense stands which outcompete native species. It can potentially spread long distances via water courses and is drought and cold tolerant, sprouting from basal shoots after dry periods.

There is some discrepancy in placement of the original distribution of H. echioides with some sources suggesting it was originally from only the western Mediterranean region (Tremetsberger et al., 2015) and others widening its native range to countries as far east as Russia and Ukraine in Europe, and Azerbaijan and Iran in central Asia (Greuter, 2006; USDA-ARS, 2016). H. echioides is considered introduced, established or naturalized in Australia, Turkmenistan, South Africa, Canada, USA, Argentina, Chile, Uruguay as well as other European countries (Holzapfel, 1994; Greuter, 2006; Stace, 2010; Sîrbu & Oprea, 2013; DAISIE, 2015; USDA-ARS, 2016).

H. echioides survives well in difficult conditions, such as drought, and is spread easily, potentially across large distances via water courses (Tosso et al., 1986; Holzapfel, 1994).

H. echioides is often associated with disturbed sites in urban and intensive agricultural habitats in the USA and Mexico (Flora of North America Editorial Committee, 2015; Vibrans, 2015). Specimens collected in Australia are frequently found in public places, which may be partly induced by the application of herbicides (Holzapfel, 1994).

In the USA, it is mostly classified as an obligate upland species which never occurs in wetlands and only in the Arid West region is it classified as rarely occurring in wetlands (USDA-NRCS, 2016).

In France and Corsica, it can be found on the edges of roads and fields and also in waste places (Tela Botnica, 2016). In New Zealand, it has been reported to be a common weed of waste land, pasture, urban areas and forest margins, and can be found in coastal to montane regions (New Zealand Plant Conservation Network, 2016).

Genetics

H. echioides has a sporophytic count of 10 and a gametophytic count of 5/10 (IPCN Chromosome Reports, 2015).

Reproductive Biology

H. echioides produces heterocarpic fruits with different achenes (Tremetsberger et al., 2015). Flowers are hermaphrodite and the plant is self-fertile. Seeds are often produced apomictically (Plants for a Future, 2012). H. echioides reproduces exclusively by seed (New Zealand Plant Conservation Network, 2016).

It is able to survive dry climates and appears to sprout from basal shoots after dry periods (Holzapfel, 1994).

The flowers are pollinated by bees and flies (Plants for a Future, 2012).

Physiology and Phenology

H. echioides usually flowers and fruits from March to July in the Americas but can also flower and fruit at other times (Vibrans, 2015). According to Plants for a Future (2012), it flowers from June to October and seeds ripen from July to October. In France it flowers from June to September (Tela Botanica, 2016). In New Zealand, it can flower and fruit all year round in warm climates, but otherwise flowers from August to May and fruits from October to July (New Zealand Plant Conservation Network, 2016).

Its ability to sprout from secondary basal shoots after the primary stem has dried out allows it to be classed as perennial (Holzapfel, 1994).

Environmental Requirements

H. echioides can grow in a wide range of soil types and prefers dry or moist soil. It does not grow well in shade but can tolerate frost (Plants for a Future, 2012).

H. echioides survives well in difficult conditions, such as drought (Tosso et al., 1986; Holzapfel, 1994).

In Crete, it has been noted as being slightly susceptible to disease from the fungus Verticillium dahlia showing Verticillium wilt symptoms (Ligoxigakis et al., 2002)

In experiments, an extract from H. echioides, cloform, acts as a good deterrent for four species of pest insects (Sitophilus granaries – adults, Tribolium confusum – adults and larvae, and Trogoferma granarium – larvae) (Daniewski et al., 1989).

Human food and beverage

• Vegetable

The following is provided by the New Zealand Plant Conservation Network (2016):

“The stem and leaf indumentum of oxtongue (Helminthotheca echioides (L.) Holub) has 2-, 3-, 4- or 5-hooked anchor hairs and the hairs of the leaves arise from a conspicuous swollen base. The involucral bracts of the flowers are in two rows, with the five outer involucral bracts ovate to cordate, and the apex of the inner bracts feather-like. Unlike our indigenous oxtongus (Picris spp.) the achenes of the introduced oxtongue (H. echioides) are dimorphic: the outer achenes, are larger, white, and pilose hairy; the inner shorter, dark-brown and glabrous. In our indigenous oxtongues (Picris spp.) the achenes are never heteromorphic.”

Due to the variable regulations around (de)registration of pesticides, your national list of registered pesticides or relevant authority should be consulted to determine which products are legally allowed for use in your country when considering chemical control. Pesticides should always be used in a lawful manner, consistent with the product's label.

Physical/mechanical control

Mowing and grazing regimes could be used to ameliorate the threat to Holocarpha macradenia in California, USA (US Fish and Wildlife Service, 2014). The addition of solarisation could improve management outcome success as well. An experiment comparing mowing, disking and solarisation on controlling invasive weeds in cool coastal California region showed that only solarisaiton methodology achieved a reduction in the existing invasive weed species and stopped a new invasion of H. echioides because the seed bank of the weed is destroyed as well as the plants (Lambrecht and D’Amore, 2010).

30/06/2016 Original text by:

Alex Hudson, Royal Botanic Gardens Kew, UK