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threetooth ragwort

serpentine groundsel, Siskiyou butterweed, western ragwort

Habit Perennials, 10–30+ cm; taprooted (caudices ascending to erect). Perennials, 7–15+ cm; fibrous-rooted (caudices relatively slender).
Stems

1 or multiple, clustered, usually glabrous, rarely sparsely floccose-tomentose, leaf axils sometimes tomentose.

1, glabrous or sparsely tomentose.

Basal leaves

(and proximal cauline, relatively thick and turgid) petiolate;

blades lanceolate or narrowly oblanceolate, 20–40+ × 5–15 mm, bases tapering, margins usually entire, sometimes sub-pinnatisect (apices subentire or dentate).

(and proximal cauline) petiolate;

blades ovate, oblanceolate, or spatulate, 10–30 × 5–20 mm, bases tapering, sometimes obtuse, margins entire, subentire, or dentate.

Cauline leaves

gradually reduced (± petiolate or sessile).

abruptly reduced (sessile, clasping; bractlike, entire).

Peduncles

bracteate, glabrous or sparsely tomentose.

bracteate (bractlets red-tinged), densely lanate-tomentose.

Ray florets

8–10(–13);

corolla laminae 5–8+ mm.

(8–)13;

corolla laminae 6–10+ mm.

Disc florets

45–60+;

corolla tubes 3–3.5 mm, limbs 4–5 mm.

35–50+;

corolla tubes 2.5–3.5 mm, limbs 3–4 mm.

Phyllaries

13 or 21, green, 6–10 mm, sparsely tomentose proximally, glabrous distally.

(13–)21, green (tips red or dark red), densely tomentose proximally.

Calyculi

inconspicuous.

conspicuous (bractlets narrow, red-tinged).

Heads

4–15+ in corymbiform arrays.

1–4+ in corymbiform arrays.

Cypselae

1.5–2.5 mm, glabrous or sparsely hirtellous on ribs;

pappi 5–6 mm.

1.5–2 mm, glabrous;

pappi 5–6 mm.

2n

= 46.

= 46.

Packera tridenticulata

Packera hesperia

Phenology Flowering late May–early Jul. Flowering mid Apr–mid Jun.
Habitat Open, dry areas, roadsides, gravelly or sandy slopes, short-grass prairies or sagebrush scrubs Serpentine derived soils, open woodland scrub
Elevation 1000–2000 m (3300–6600 ft) 500–2500 m (1600–8200 ft)
Distribution
from FNA
CO; KS; ND; NE; NM; OK; SD; TX; WY
[WildflowerSearch map]
from FNA
CA; OR
[WildflowerSearch map]
[BONAP county map]
Discussion

Packera tridenticulata is found throughout the central High Plains, in the foothills of the Rocky Mountains, and in high valleys to the west of the Rocky Mountain front. It tends to grow in clumps; the multiple stems arise from well-developed taproots. It apparently hybridizes with P. neomexicana var. mutabilis where their ranges overlap.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Of conservation concern.

Packera hesperia is known only from the Siskiyou Mountains.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source FNA vol. 20, p. 601. FNA vol. 20, p. 589.
Parent taxa Asteraceae > tribe Senecioneae > Packera Asteraceae > tribe Senecioneae > Packera
Sibling taxa
P. anonyma, P. antennariifolia, P. aurea, P. bernardina, P. bolanderi, P. breweri, P. cana, P. cardamine, P. castoreus, P. clevelandii, P. contermina, P. crocata, P. cymbalaria, P. cynthioides, P. debilis, P. dimorphophylla, P. eurycephala, P. fendleri, P. flettii, P. franciscana, P. ganderi, P. glabella, P. greenei, P. hartiana, P. hesperia, P. hyperborealis, P. indecora, P. ionophylla, P. layneae, P. macounii, P. malmstenii, P. millefolium, P. millelobata, P. multilobata, P. musiniensis, P. neomexicana, P. obovata, P. ogotorukensis, P. pauciflora, P. paupercula, P. plattensis, P. porteri, P. pseudaurea, P. quercetorum, P. sanguisorboides, P. schweinitziana, P. spellenbergii, P. streptanthifolia, P. subnuda, P. tampicana, P. texensis, P. tomentosa, P. werneriifolia
P. anonyma, P. antennariifolia, P. aurea, P. bernardina, P. bolanderi, P. breweri, P. cana, P. cardamine, P. castoreus, P. clevelandii, P. contermina, P. crocata, P. cymbalaria, P. cynthioides, P. debilis, P. dimorphophylla, P. eurycephala, P. fendleri, P. flettii, P. franciscana, P. ganderi, P. glabella, P. greenei, P. hartiana, P. hyperborealis, P. indecora, P. ionophylla, P. layneae, P. macounii, P. malmstenii, P. millefolium, P. millelobata, P. multilobata, P. musiniensis, P. neomexicana, P. obovata, P. ogotorukensis, P. pauciflora, P. paupercula, P. plattensis, P. porteri, P. pseudaurea, P. quercetorum, P. sanguisorboides, P. schweinitziana, P. spellenbergii, P. streptanthifolia, P. subnuda, P. tampicana, P. texensis, P. tomentosa, P. tridenticulata, P. werneriifolia
Synonyms Senecio tridenticulatus, Senecio acutidens, Senecio compactus, Senecio densus, Senecio oblanceolatus Senecio hesperius, Senecio auleticus
Name authority (Rydberg) W. A. Weber & Á. Löve: Phytologia 49: 48. (1981) (Greene) W. A. Weber & Á. Löve: Phytologia 49: 47. (1981)
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