Gumweed (3)

The Grindelia genus, Gumweeds, ooze a whitish, viscous, resinous fluid from their flower buds so are very recognizable. There are conflicting descriptions of the species, but I think these three are unique enough to be identified individually.

Grindelia nuda

Curlytop Gumweed
Grindelia nuda var. aphanactis (G. squarrosa var. nuda)

Family: Sunflower (Asteraceae)
AKA: Rayless Gumweed, Resinweed
Photo taken on: October 13, 2010
Location: White Rock, NM
Life Zones: Plains to foothills
Habitat: Dry open areas, pinyon-juniper woodlands

Grows to 16" with a wiry, reddish stem.  Leaves are oblong and  toothed with no stalks. Bracts are sticky and curl backwards. Flower heads have only disk flowers.

Recognized by the USDA Plants Database but considered a variety of G. squarrosa by Flora of North America.

Grindelia inornata

Colorado Gumweed
Grindelia inornata

Family: Sunflower (Asteraceae)
AKA: Resinweed, Rayless Gumweed
Photo taken on: September 17, 2011
Location: Wet Mountains, Eastern CO
Life Zones: Plains to foothills
Habitat: Dry open slopes, fields

Grows to 30" with stout stems and fleshy leaves. Flower heads do not have ray flowers, are 1" across and very sticky. Bracts are bright green and curved backwards. Grows south from Denver on the eastern slope.

Identified from G. K. Guennel's Wildflowers of Colorado. Flora of North America does not recognize it. The USDA Plants Database does but gives no synonyms for it.

Grindelia squarrosa

Curlycup Gumweed
Grindelia squarrosa

Family: Sunflower (Asteraceae)
AKA: Resinweed
Photo taken on: August 26, 2014
Location: SR 114, Saguache, CO
Life Zones: Plains to foothills
Habitat: Roadsides, waste places

Grows to 2ft with a green or whitish stem.  Leaves are oblong and toothed with no stalks. Bracts are in 5 to 6 rows and are strongly hooked. Ray flowers may or may not be present.

 Grindelia squarrosa

Flora of North America reference.

Yellow Round Clusters