The most well know of this group of yellow-flowered plants is Dandelion (Taraxacum officinale). Renown for its showy seedhead, Dandelions beckon children of all ages to “tell the time” as they blow the tiny parachutes until all are dislodged.
But it is Catsear (Hypochoeris radicata), also called False Dandelion or Flatweed, that is generally more numerous and widespread. And it is also the plant species that causes most concern to horse owners, due to its link to Australian Stringhalt.
Few people even realise that there are two other very similar species that masquerade as Catsear.
All four of these plants are members of the Asteraceae (Daisy) family, but all lack a prominent flower centre like classic daisy flowers.
Australian Stringhalt (Equine Reflex Hypertonia) has only ever been associated with Catsear (Hypochoeris radicata) and is NOT associated with Dandelion (Taraxacum officinale) or Capeweed (Arctotheca calendula). This widely held, but incorrect belief is probably due to naming confusion, since Catsear is often called False Dandelion, and Capeweed is an African plant known locally as Cape Dandelion.
Catsear ONLY causes Stringhalt under very specific environmental conditions, however researchers are yet to determine the actual mechanism by which this happens. Horses are the only animals known to be affected, and are only at risk if eating highly stressed Catsear plants, usually during drought
conditions. Researchers believe that drought stress causes the leaves close to ground levels to release a toxin, as a defence against overgrazing. Drought conditions also coincides with horses being forced to graze plants hard at the base, and increase the proportion of their diet comprising this resilient
tap-rooted plant.
The majority of horses eat significant amounts of both heads and leaves without any problems.
The plant is actually known to be a quality fodder source. But be on the lookout, particularly when moisture stress is evident in the paddocks.
My free PDF Fact Sheet on Catsear and Stringhalt gives more specific ID hints on these species.
