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threetooth ragwort

New Mexico groundsel

Habit Perennials, 10–30+ cm; taprooted (caudices ascending to erect). Perennials, biennials, or annuals, 20–50+ cm; fibrous-rooted, taprooted, or ± rhizomatous (bases branched, horizontal or ascending to erect).
Stems

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

1 or 2–5+, clustered, lanate- or arachno-tomentose or 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).

(often abaxially cyanic) petiolate (petioles hairy to glabrate);

blades ovate to lanceolate or narrowly lanceolate, 20–60+ × 10–30+ mm, bases abruptly contracted to tapering, margins subentire or denticulate to subserrate (abaxial faces usually tomentose, adaxials frequently glabrate).

Cauline leaves

gradually reduced (± petiolate or sessile).

gradually or abruptly reduced (proximal petiolate, similar to basals; mids and distals sessile, lanceolate, entire).

Peduncles

bracteate, glabrous or sparsely tomentose.

conspicuously bracteate, usually hairy.

Ray florets

8–10(–13);

corolla laminae 5–8+ mm.

(5–)8 or 13;

corolla laminae 4–10 mm.

Disc florets

45–60+;

corolla tubes 3–3.5 mm, limbs 4–5 mm.

40–60+;

corolla tubes 1.5–2.5 mm, limbs 3.5–4.5 mm.

Phyllaries

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

13 or 21, green or yellowish, 4–7+ mm, tomentose to glabrescent.

Calyculi

inconspicuous.

conspicuous.

Heads

4–15+ in corymbiform arrays.

3–20+ in open or compact, corymbiform to subumbelliform arrays (subtended by smaller arrays arising from leaf axils).

Cypselae

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

pappi 5–6 mm.

1.5–2.5 mm, usually hirtellous on ribs, sometimes glabrous;

pappi 5–6+ mm.

2n

= 46.

= 44, 46, 92.

Packera tridenticulata

Packera neomexicana

Phenology Flowering late May–early Jul.
Habitat Open, dry areas, roadsides, gravelly or sandy slopes, short-grass prairies or sagebrush scrubs
Elevation 1000–2000 m (3300–6600 ft)
Distribution
from FNA
CO; KS; ND; NE; NM; OK; SD; TX; WY
[WildflowerSearch map]
from FNA
AZ; CO; NM; UT; w Mexico
[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.)

Varieties 3 (3 in the flora).

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

Key
1. Plants loosely tomentose or glabrate; basal leaves: blades narrowly lanceolate, margins subentire or irregularly dentate
var. mutabilis
1. Plants usually densely lanate or woolly tomentose, seldom glabrate; basal leaves: blades ovate or broadly lanceolate, margins dentate to deeply dentate or dissected
→ 2
2. Plants taprooted; cauline leaves conspicuous
var. neomexicana
2. Plants rhizomatous or fibrous-rooted; cauline leaves inconspicuous (bractlike)
var. toumeyi
Source FNA vol. 20, p. 601. FNA vol. 20, p. 593.
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. layneae, P. macounii, P. malmstenii, P. millefolium, P. millelobata, P. multilobata, P. musiniensis, 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
Subordinate taxa
P. neomexicana var. mutabilis, P. neomexicana var. neomexicana, P. neomexicana var. toumeyi
Synonyms Senecio tridenticulatus, Senecio acutidens, Senecio compactus, Senecio densus, Senecio oblanceolatus Senecio neomexicanus
Name authority (Rydberg) W. A. Weber & Á. Löve: Phytologia 49: 48. (1981) (A. Gray) W. A. Weber & Á. Löve: Phytologia 49: 47. (1981)
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