OregonFlora: Grindelia integrifolia vs. Grindelia adenodonta

	Grindelia integrifolia	Grindelia adenodonta
	Puget Sound gumplant, Willamette Valley gumweed
Habit	Plants perennial.
Stems	erect, 40–63 cm, with multicellular, crinkled, matted hairs; and shorter gland-tipped hairs.
Basal leaves	narrowly oblanceolate, narrowed to base, 4–17 × 0.6–3 cm; tips obtuse to abruptly acute.
Cauline leaves	lanceolate, 4–12.5 × 0.8–3.5 cm, gradually reduced distally, bases cordate; margins entire to serrate; teeth with a hard bump; tips acuminate; surfaces with upright, glandular hairs, sometimes also with non-glandular hairs, lacking punctate glands.
Involucres	5–10 × 7–22 mm.
Ray florets	18–28; rays 8–12 × 2.1–2.8 mm.
Disc florets	4.5–6.2 mm.
Phyllaries	in 3–4 series, with glandular hairs, tips of outer spreading, tips of inner erect to spreading.
Fruits	3.5–4 × 1.8–2 mm, white to brown; crowns 0.05–0.3 mm; pappus awns 2–3 mm.
Heads	3–32 per main stem; borne singly or in tight clusters of 2–3, radiate; peduncles 0–15 cm.
2n	=12.

	Grindelia integrifolia	Grindelia adenodonta
Distribution	[WildflowerSearch map] [BONAP county map]	[BONAP county map]
Discussion	Freshwater marshes. Flowering Jun–Sep. 0–300 m. Casc, WV. Native. This species is easily identified by long, multicellular hairs on the stems that are visible with the naked eye and stalked glands on the leaves. It hybridizes extensively with G. nana almost throughout its range (see separate discussion of hybrids).
Source	Flora of Oregon, volume 2, page 275 Abigail (Abby) Moore
Sibling taxa	G. hirsutula, G. integrifolia x Grindelia nana, G. integrifolia x Grindelia nana var. nana, G. nana, G. squarrosa, G. stricta	G. hirsutula, G. integrifolia, G. integrifolia x Grindelia nana, G. integrifolia x Grindelia nana var. nana, G. nana, G. squarrosa, G. stricta
Synonyms	Grindelia integrifolia var. integrifolia, Grindelia nana var. integrifolia
Web links	Local floras: OR, WA Local Web sites: Flora NW, PNW Herbaria, Turner Photog. WildflowerSearch iNaturalist (observations) USDA Plants Database LBJ Wildflower Center SEINet Plants of the World Online Encyclopedia of Life Wikipedia Google Image Search	Local Web sites: Flora NW, PNW Herbaria WildflowerSearch iNaturalist (observations) USDA Plants Database LBJ Wildflower Center SEINet Plants of the World Online Encyclopedia of Life Wikipedia Google Image Search

Grindelia adenodonta

Puget Sound gumplant, Willamette Valley gumweed

Habit

Plants perennial.

Stems

erect, 40–63 cm, with multicellular, crinkled, matted hairs; and shorter gland-tipped hairs.

Basal leaves

narrowly oblanceolate, narrowed to base, 4–17 × 0.6–3 cm;

tips obtuse to abruptly acute.

Cauline leaves

lanceolate, 4–12.5 × 0.8–3.5 cm, gradually reduced distally, bases cordate;

margins entire to serrate;

teeth with a hard bump;

tips acuminate;

surfaces with upright, glandular hairs, sometimes also with non-glandular hairs, lacking punctate glands.

Involucres

5–10 × 7–22 mm.

Ray florets

18–28;

rays 8–12 × 2.1–2.8 mm.

Disc florets

4.5–6.2 mm.

Phyllaries

in 3–4 series, with glandular hairs, tips of outer spreading, tips of inner erect to spreading.

Fruits

3.5–4 × 1.8–2 mm, white to brown; crowns 0.05–0.3 mm;

pappus awns 2–3 mm.

Heads

3–32 per main stem; borne singly or in tight clusters of 2–3, radiate;

peduncles 0–15 cm.

=12.

Grindelia adenodonta

Distribution

[WildflowerSearch map]

[BONAP county map]

Discussion

Freshwater marshes. Flowering Jun–Sep. 0–300 m. Casc, WV. Native.

This species is easily identified by long, multicellular hairs on the stems that are visible with the naked eye and stalked glands on the leaves. It hybridizes extensively with G. nana almost throughout its range (see separate discussion of hybrids).

Source

Flora of Oregon, volume 2, page 275
Abigail (Abby) Moore

Sibling taxa