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threetooth ragwort

Layne's ragwort

Habit Perennials, 10–30+ cm; taprooted (caudices ascending to erect). Perennials, 40–70+ cm; taprooted (caudices erect to suberect, branched, stout).
Stems

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

1 or 3–4+, clustered, sparsely tomentose to glabrescent.

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, relatively thick and turgid) petiolate;

blades narrowly elliptic or lanceolate to oblanceolate, 40–70+ × 5–20+ mm, bases tapering, margins entire or subentire to weakly and irregularly dentate (especially at apices).

Cauline leaves

gradually reduced (± petiolate or sessile).

gradually reduced (distal sessile, bractlike).

Peduncles

bracteate, glabrous or sparsely tomentose.

bracteate (bractlets usually red-tipped), sparsely tomentose to glabrate.

Ray florets

8–10(–13);

corolla laminae 5–8+ mm.

5 or 8;

corolla laminae 12–16 mm.

Disc florets

45–60+;

corolla tubes 3–3.5 mm, limbs 4–5 mm.

50–60+;

corolla tubes 3.5–4.5 mm, limbs 4.5–5.5 mm.

Phyllaries

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

13 or 21, dark green proximally, becoming light green distally (tips red), 7–11+ mm, floccose-tomentose proximally.

Calyculi

inconspicuous.

conspicuous (bractlets red-tipped).

Heads

4–15+ in corymbiform arrays.

5–12+ in open, cymiform arrays.

Cypselae

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

pappi 5–6 mm.

2.5–3.5 mm, glabrous;

pappi 7–8 mm.

2n

= 46.

= 92.

Packera tridenticulata

Packera layneae

Phenology Flowering late May–early Jul. Flowering early May–early Jul.
Habitat Open, dry areas, roadsides, gravelly or sandy slopes, short-grass prairies or sagebrush scrubs Openings, disturbed areas, in chaparral, serpentine soils
Elevation 1000–2000 m (3300–6600 ft) 300–900 m (1000–3000 ft)
Distribution
from FNA
CO; KS; ND; NE; NM; OK; SD; TX; WY
[WildflowerSearch map]
from FNA
CA
[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 layneae is known only from the foothills of the western slope of the Sierra Nevada.

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

Source FNA vol. 20, p. 601. FNA vol. 20, p. 590.
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. hesperia, P. hyperborealis, P. indecora, P. ionophylla, 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 layneae, Senecio fastigiatus var. layneae
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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