Yellow Thistle Argemone mexicana

Originally from Mexico, Prickly Poppy has naturalized in many parts of the world.  In regions that experience a pronounced dry season, it can be found growing in its natural habitat of dry soils along roadsides, waste places and fields.  In more temperate locations, it can flower and produce seed year round.  

In many locations worldwide, it has become a nuisance plant in crops and is listed as a serious agricultural weed.  Where fields or pastures have been overgrazed, its invasive nature has allowed it to multiply.  In addition to humans, this plant is toxic for grazing animals.

The solitary, showy flowers form at the tips of the branches.  When cut, a yellow juice or sap is exuded.  The leaves are thistle-like and are not attached to the stem by petioles.  The grayish-white veins on the leaves stand out against the blue-green leaf surface.  

Insects, Diseases, and Other Plant Problems:  White flies, thrips and aphids can affect this plant. All parts of this plant are toxic if ingested.  The level of toxicity varies depending on the person's size, age, and physical condition.  Alkaloids from the plant are similar to those found in opium poppy.