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threetooth ragwort

balsam groundsel, Canadian butterweed

Habit Perennials, 10–30+ cm; taprooted (caudices ascending to erect). Perennials, 20–45+ cm; subrhizomatous (bases weakly branched, ascending to erect).
Stems

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

1 or 2–4, loosely clustered, glabrous or sparsely tomentose proximally.

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).

petiolate;

blades lanceolate to narrowly elliptic or oblanceolate, 30–60+ × 10–20+ mm, bases tapering, sometimes obtuse, margins subentire to dentate or serrate.

Cauline leaves

gradually reduced (± petiolate or sessile).

gradually reduced (proximals petiolate, sublyrate; mids sessile, not clasping, lanceolate, dissected, incised, or lacerate; distals sessile, bractlike).

Peduncles

bracteate, glabrous or sparsely tomentose.

usually bracteate, sometimes ebracteate, glabrous.

Ray florets

8–10(–13);

corolla laminae 5–8+ mm.

0, 8, or 13;

corolla laminae (pale yellow) 5–10+ mm.

Disc florets

45–60+;

corolla tubes 3–3.5 mm, limbs 4–5 mm.

50–65+;

corolla tubes 2–3 mm, limbs 2–3 mm.

Phyllaries

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

13 or 21, green, 5–8+ mm, glabrous.

Calyculi

inconspicuous.

inconspicuous.

Heads

4–15+ in corymbiform arrays.

2–10+ in loose or compact, corymbiform arrays.

Cypselae

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

pappi 5–6 mm.

1–2 mm, usually glabrous, sometimes hispidulous on ribs;

pappi 3.5–4.5 mm.

2n

= 46.

= 44, 46, 92.

Packera tridenticulata

Packera paupercula

Phenology Flowering late May–early Jul. Flowering May–late Jun (south), late Jun–early Aug (north).
Habitat Open, dry areas, roadsides, gravelly or sandy slopes, short-grass prairies or sagebrush scrubs Wet meadows, open woodlands, along streams, rocky outcrops
Elevation 1000–2000 m (3300–6600 ft) 0–3000 m (0–9800 ft)
Distribution
from FNA
CO; KS; ND; NE; NM; OK; SD; TX; WY
[WildflowerSearch map]
from FNA
AK; AL; CO; DC; GA; IA; ID; IL; IN; KY; MA; MD; ME; MI; MN; MT; NC; ND; NH; NJ; NY; OH; PA; SD; TN; UT; VT; WA; WI; WV; WY; AB; BC; MB; NB; NL; NS; NT; NU; ON; PE; QC; SK; YT
[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.)

Ecologically and morphologically, Packera paupercula is the most variable species of the genus in North America. Some “phases” have been treated as separate species, subspecies, varieties, forms, and races. Variation within P. paupercula hints at some interesting evolutionary relationships; characteristics used to separate taxa overlap. Much of the morphologic variation in this species may be due to hybridization and introgression. I do not recognize any of the infraspecific taxa that have been proposed.

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

Source FNA vol. 20, p. 601. FNA vol. 20, p. 595.
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. neomexicana, P. obovata, P. ogotorukensis, P. pauciflora, 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 pauperculus, Senecio balsamitae, Senecio balsamitae var. firmifolius, Senecio balsamitae var. thomsoniensis, Senecio crawfordii, Senecio flavovirens, Senecio gaspensis, Senecio multnomensis, Senecio robbinsii var. subtomentosus, Senecio tweedyi
Name authority (Rydberg) W. A. Weber & Á. Löve: Phytologia 49: 48. (1981) (Michaux) Á. Löve & D. Löve: Bot. Not. 128: 520. (1976)
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