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     The genus Grindelia was described in 1807 by Willdenow, based on specimens of Grindelia inuloides that were grown in the Royal Botanical Garden in Berlin. These plants were grown from seed collected in Mexico by Humboldt and Bonpland.

     The three species pictured on this page are commonly called "Gumweed" because of their very sticky phyllaries. "Grindelia" honors David Hieronymus Grindel, Russian chemist, pharmacist, and doctor.  (More biographical information about Grindel.)

Grindelia arizonica
Grindelia arizonica(Arizona Gumweed)
Asteraceae (Sunflower Family)

Foothills. Openings. Summer, fall.
Prater Ridge Trail, Mesa Verde National Park, August 13, 2005.

Grindelia arizonica typically grows several feet high and wide in a bushy shape with numerous bright yellow flowerheads which often have fairly erect ray flowers. Grindelia flowers exude a strange and strong medicinal smell. Stems of G. arizonica are often red. The toothed leaves are well-space along the stem giving the plant its characteristic open appearance.

Grindelia arizonica
Grindelia arizonica (Arizona Gumweed)
Asteraceae (Sunflower Family)

Foothills. Openings. Summer, fall.
Prater Ridge Trail, Mesa Verde National Park, August 13, 2005.

The very prominent phyllaries (the green overlapping structures below the yellow ray flowers) are sticky, in four or five rows, and, in this species, are vertical and pressed against the main floral body, not curved back at the tips. (See G. squarrosa below.)

 

Grindelia hirsutula
Grindelia hirsutula.  Synonym: Grindelia fastigiata. (Hairy Gumweed)
Asteraceae (Sunflower Family)

Semi-desert. Openings. Summer, fall.
Hunter Canyon, Utah, September 26, 2005.

Grindelia hirsutula grows to four feet tall in sand or clay soils in dry open places and along washes, as in the photograph at left. This species is just as sticky and aromatic as the other Grindelias shown on this page. G. hirsutula hybridizes with G. squarrosa.

Although ray flowers are present on this species in many areas, in the Four Corners region the plant often has no ray flowers.

"Hirsute" is Latin for "hairy" and "hirsutula" is "a little hairy". (Botanically, "hirsute" means "clothed with coarse, stiff hairs".) "Fastigi" is Latin for "pointed", perhaps referring to the sharply pointed bracts and/or to the pointed appearance of the disk flowers as shown in the photograph below.

The name of this species is controversial. Weber accepts it at species status but does not accept G. fastigiata; Ackerfield accepts both (with three varieties of G. hirsutula); Kartesz indicates that G. fastigiata is rare in the Four Corners region and that G. hirsutula is a species found only in far western California, never in the Four Corners states; Welsh accepts only G. fastigiata and says G. hirsutula is a synonym; Flora of the Four Corners Region does not indicate that either species exists in the Four Corners region; and Flora Neomexicana III indicates that G. hirsutula is found in a very limited area of north central New Mexico.

The Flora of North America provides a detailed analysis of all the various species (click to read) and indicates, 

Grindelia hirsutula includes 30 or more reputedly distinct, local, regional, or ecotypic [taxa] that have been named at species or infraspecific rank. Locally, such [taxa] are easily recognized; in a broad view, they intergrade with other [taxa] and are parts of a heterogeneous continuum. Taxonomies that have attempted to recognize the [taxa] as distinct "taxa" have led to almost as many specimens determined as "intermediate" as are assigned to the named "taxa."

FNA includes G. fastigiata among the 30 taxa mentioned above. In other words, the FNA does not accept G. fastigiata as a distinct taxon.

Grindelia hirsutula was named and described by William Jackson Hooker and George Arnott in 1833, from collections made by Lay and Collie on the 1825-1828 Beechey Expedition.

Grindelia hirsutula
Grindelia hirsutula. Synonym: Grindelia fastigiata. (Hairy Gumweed)
Asteraceae (Sunflower Family)

Semi-desert, foothills. Openings. Summer, fall.
Hunter Canyon, Utah, September 26, 2005 and Arches National Park, Utah, May 27, 2016.

Grindelia hirsutula

 

Grindelia squarrosa
Grindelia squarrosa(Curly Gumweed)
Asteraceae (Sunflower Family)

Foothills. Openings. Summer, fall.
Dolores River Canyon, August 20, 2005.

Stems of G. squarrosa are usually green, not red, and leaves are more serrated than in G. arizonica.

Meriwether Lewis collected this plant on the banks of the Missouri River, probably in 1806, and Pursh named it Donia squarrosa in 1814.  It was renamed Grindelia squarrosa by Dunal in 1819.

Grindelia squarrosa
Grindelia squarrosa (Curly Gumweed)
Asteraceae (Sunflower Family)

Foothills. Openings. Summer, fall.
Dolores River Canyon, August 20, 2005.

From a distance, the species of Grindelia pictured on this page are very similar looking.  A close look shows that the most noticeable difference is in the curving of the phyllaries.  The arching ("recurved") phyllaries of G. squarrosa are prominent and a key to identifying this species.

Several floras, including the Flora of North America, indicate that G. squarrosa can sometimes be found without ray flowers. Other floras, such as, Ackerfield's Flora of Colorado indicate that this species always has ray flowers and that the rayless Grindelias are G. fastigiata or G. nuda, neither of which are accepted as species by FNA.

"Squarrosa" is Latin for "scaly or rough", but botanically means "recurved", i.e., curved backwards. This recurved shape would, of course, make the phyllaries feel scaly or rough. 

 

Range map © John Kartesz,
Floristic Synthesis of North America

State Color Key

Species present in state and native
Species present in state and exotic
Species not present in state

County Color Key

Species present and not rare
Species present and rare
Species extirpated (historic)
Species extinct
Species noxious
Species exotic and present
Native species, but adventive in state
Eradicated
Questionable presence

Range map for Grindelia arizonica  

Grindelia fastigiata

Range map for Grindelia fastigiata. This name is considered a synonym by the Flora of North America. The taxon is included in G. hirsutula. See the note immediately below and the discussion above.

Grindelia hirsutula

Range map for Grindelia hirsutula (Range according to Kartesz, but FNA places G. hirsutula in all western states and more. Click to see map.)

Range map for Grindelia squarrosa