Henny Penny Farmette

The star thistle blooms in yellow bursts of color over the brown, drought-parched hills of the Bay Area during summer. Widely considered a noxious, invasive weed, the yellow star thistle’s blooms serve as a source of food for the honeybees during drought conditions when flower sources become scant.

While naturalists, government officials, land management people, ranchers, gardeners, farmers, and road and park maintenance workers consider the yellow star thistle challenging to control, others lament indigenous plants suffer or die because the yellow star thistle depletes the soil of moisture. Its one redeeming value appears to be as a food source for the bees.

Local beekeepers understand the value of the yellow star thistle during severe drought when water rationing in many counties mean few if any flowers are left blooming in August and September. While the plant’s nectar is great for the bees, it’s bad news for horses. Feeding on yellow star thistle over time can cause a horse malady known as chewing disease.

Also called St. Barnaby’s thistle and yellow cockspur, the yellow star thistle’s long tap root keeps it going while other plants around it die from lack of water. In Europe where the plant is indigenous, it is held in check by other plants that have co-evolved with it and by herbivores, the enemies of yellow star thistle. However, that’s not the case in the United States.

Since it was introduced to America in the early part of the 20th Century, the yellow star thistle has spread faster than a California wildfire and now covers some 15 million acres, just in this state alone. It is also considered a noxious, invasive weed in 35 other states. But the honeybees don’t care as long as there are enough of those yellow blooms to get them through the dog days of summer.