Grindelia squarrosa, also known as a curly-top gumweed or curlycup gumweed, is a small North American biennial or short-lived perennial plant.[2]
Description
G. squarrosa is a decumbent to erect, much-branched perennial herb or subshrub growing up to 100 centimetres (39+1⁄2 inches) tall. The leaves are 1.5–7.5 cm (1⁄2–3 in) long,[3] gray-green, crenate with each tooth having a yellow bump near its tip, and resinous.[4][5]
The plant produces numerous flower heads in open, branching arrays. The flower bract (involucre) is resinous and consists of multiple overlapping rows of phyllaries with tips that are strongly curled outward, sometimes curling back to form a circle.[4] Each head usually contains 12–40 yellow ray flowers, though sometimes the rays are absent. These surround many small disc flowers. The plant blooms from July through late September.[4][6][5] The brown seed is usually four-angled, with loose scales.[3]
A form with rayless flowers is sometimes considered a distinct species.[citation needed]
It is often found in dry, open areas[3] and disturbed roadsides and streamsides, occurring between 700 metres (2,300 feet) and 2,300 metres (7,500 feet) in elevation.[4]
It is used as a traditional medicinal plant by Shoshone peoples in various regions.[13] The Gosiute language name for the plant is mu’-ha-kûm.[16] The Lakota language name for the plant is pteíčhiyuȟa.
The plant is being explored as a potential source of biofuel due to its high content of mono- and di-terpenes which can be converted to a fuel analogous to kerosene or jet fuel.[18] The plant's adaptation to arid climates makes it an attractive option as its cultivation in desert areas would not compete with traditional food crops.
^Niering, William A.; Olmstead, Nancy C. (1985) [1979]. The Audubon Society Field Guide to North American Wildflowers, Eastern Region. Knopf. p. 382. ISBN0-394-50432-1.