Prenanthes trifoliolata

(Cassini) Fernald

Contr. Bot. Vermont 8: 89. 1900.

Common names: Threeleaved rattlesnakeroot prenanthe trifoliolée
IllustratedEndemic
Basionym: Nabalus trifoliolatus Cassini in F. Cuvier, Dict. Sci. Nat. ed. 2, 34: 95. 1825
Synonyms: P. trifoliolata var. nana (Bigelow) Fernald
Treatment appears in FNA Volume 19. Treatment on page 271. Mentioned on page 265, 270.

Plants 10–150 cm; taproots thick, with lateral roots. Stems erect, green or sometimes mottled purple, usually glabrous, sometimes tomentulose distally. Leaves: proximal usually present at flowering; petiolate (petioles winged, 1–25 cm); blades deltate to ovate, 3–12 × 1–15 cm, thin, bases cordate to rounded, margins palmately 3 (–5) -lobed to divided (then leaves compound), lobes and sinuses usually angular (not rounded), lobes short and lanceolate, ultimate margins irregularly serrate, faces glabrous or ciliate along abaxial veins and margins; distal reduced, palmately lobed or entire. Heads (2–7, nodding, in irregular clusters) in racemiform or paniculiform arrays. Involucres narrowly campanulate (bases attenuate to bracteate peduncles), 10–13 × 4–5 mm. Calyculi of 5–7, green to dark green or blackish, triangular bractlets 1–3 mm, glabrous. Phyllaries 7–10, green to dark green or blackish proximally, lanceolate to elliptic, 10–11 mm, margins scarious, sometimes ciliate, faces glabrous. Florets 8–13; corollas pale-yellow, 9–15 mm. Cypselae tan to brown, subcylindric, subterete to angled, 4–5 mm, distinctly 8–11-ribbed; pappi pale-yellow, 7–9 mm. 2n = 16.


Phenology: Flowering Aug–Oct.
Habitat: Moist oak-hickory woods, swampy thickets, sandy areas, cliffs, sometimes saline habitats
Elevation: 0–1400 m

Distribution

V19-372-distribution-map.gif

St. Pierre and Miquelon, N.B., Nfld. and Labr., N.S., Ont., P.E.I., Que., Conn., Ga., Ind., Ky., Maine, Md., Mass., Mich., N.H., N.J., N.Y., N.C., Ohio, Pa., R.I., S.C., Tenn., Vt., Va., W.Va.

Discussion

Prenanthes trifoliolata is recognized by its relatively large, palmately 3–5-lobed leaves with angular lobes and sinuses, basally attenuate involucres, dark green and glabrous calyculi and phyllaries, and pale yellow corollas. Dwarf plants with deeply parted leaves found in alpine areas of northern New England and Canada have been recognized as P. nana or P. trifoliolata var. nana. This form is probably no more than a phenotypic adaptation to harsh environments. In at least some localities, it intergrades with more typical P. trifoliolata at lower elevations.

Hybrids between Prenanthes trifoliolata and P. racemosa, known as P. ×mainensis A. Gray, have been found in Maine, New Brunswick, Nova Scotia, and southern Quebec, usually where the two parents come together in cliff or saline habitats. The leaves of the hybrids are intermediate between 3-lobed and spatulate, the distal are sessile, the heads are nodding, and the phyllaries are glabrous, as in the P. trifoliolata parent.

Selected References

None.

Lower Taxa

None.

No values specified."fine" is not a number.

... more about "Prenanthes trifoliolata"
not beaked +  and truncate +
scarious +
ovate +  and lanceolate +
paniculiform +  and racemiform +
indeterminate +  and determinate +
David J. Bogler +
(Cassini) Fernald +
cordate +  and rounded +
Nabalus trifoliolatus +
compound +  and simple +
3 cm30 mm <br />0.03 m <br /> (12 cm120 mm <br />0.12 m <br />) +
deltate;ovate +
tuberculate +, rugose +, muricate +  and smooth +
triangular +
0.1 cm1 mm <br />0.001 m <br /> (0.3 cm3 mm <br />0.003 m <br />) +
filiform +
Threeleaved rattlesnakeroot +  and prenanthe trifoliolée +
zygomorphic +, actinomorphic +  and (3-)5-merous +
0.9 cm9 mm <br />0.009 m <br /> (1.5 cm15 mm <br />0.015 m <br />) +
tan +  and brown +
subterete +  and angled +
entire +  and lobed +
St. Pierre and Miquelon +, N.B. +, Nfld. and Labr. +, N.S. +, Ont. +, P.E.I. +, Que. +, Conn. +, Ga. +, Ind. +, Ky. +, Maine +, Md. +, Mass. +, Mich. +, N.H. +, N.J. +, N.Y. +, N.C. +, Ohio +, Pa. +, R.I. +, S.C. +, Tenn. +, Vt. +, Va. +  and W.Va. +
0–1400 m +
glabrous +  and ciliate +
winged +  and beaked +
dispersed +
Moist oak-hickory woods, swampy thickets, sandy areas, cliffs, sometimes saline habitats +
indeterminate +
each +  and sessile +
0.2 cm2 mm <br />0.002 m <br /> (1.4 cm14 mm <br />0.014 m <br />) +
1 cm10 mm <br />0.01 m <br /> (1.3 cm13 mm <br />0.013 m <br />) +
campanulate +
0.4 cm4 mm <br />0.004 m <br /> (0.5 cm5 mm <br />0.005 m <br />) +
cauline +  and basal +
lanceolate +
palmately 3(-5)-lobed +  and divided +
2-carpellate +
pale-yellow +
persistent +
0.7 cm7 mm <br />0.007 m <br /> (0.9 cm9 mm <br />0.009 m <br />) +
Flowering Aug–Oct. +
connate +  and distinct +
7 +  and 10 +
subequal +  and unequal +
1 cm10 mm <br />0.01 m <br /> (1.1 cm11 mm <br />0.011 m <br />) +
Contr. Bot. Vermont +
exalbuminous +
Illustrated +  and Endemic +
mottled purple +, sometimes +  and green +
tomentulose +  and glabrous +
1 +  and 5 +
appendaged +  and truncate +
papillate +
P. trifoliolata var. nana +
Prenanthes trifoliolata +
Prenanthes +
species +
5 cm50 mm <br />0.05 m <br /> (250 cm2,500 mm <br />2.5 m <br />) +