Chaenorhinum minus subsp. minus

WeedyIntroducedIllustrated
Treatment appears in FNA Volume 17. Treatment on page 18. Mentioned on page 19.

Stems much-branched from or near base, sometimes unbranched, often zigzag, (4–) 8–28 (–40) cm. Leaves: blade 5–15 (–30) × 1–4 (–5) mm, base tapered, apex obtuse to acute, surfaces glandular-pubescent. Pedicels ascending. Flowers: calyx lobes accrescent, abaxial 1.5–2.5 × 0.3–0.4 mm, adaxial 2.8–3.5 × 0.4–0.8 mm, margins entire, apex obtuse; corolla 8–11 mm (including 1–2.3 mm spur), sparsely glandular-pubescent externally, glandular-pubescent internally on abaxial surface, especially along ridges of palate and into throat, throat 2–3 mm diam., abaxial lobes spreading, adaxial projecting; stamens included, anthers opposite, navicular, marginally coherent, pollen-sacs of longer pair of stamens 0.3–0.4 mm, of shorter pair of stamens 0.1–0.2 mm, glabrous; ovary glandular-pubescent; style 1.5–2 mm, glandular-pubescent proximally. Capsules obovoid to ellipsoid, 4–5.4 × 2–3.6 mm, glandular-pubescent distally. Seeds 0.6–0.9 mm, prominently ribbed longitudinally. 2n = 14, 28 (both Europe).


Phenology: Flowering May–Oct.
Habitat: Gravelly railroad rights-of-way, road shoulders, urban areas, stream beds.
Elevation: 0–1600 m.

Distribution

Introduced; Alta., B.C., Man., N.B., Nfld. and Labr. (Nfld.), N.W.T., N.S., Ont., P.E.I., Que., Sask., Ala., Ark., Colo., Conn., Del., Ga., Idaho, Ill., Ind., Iowa, Kans., Ky., La., Maine, Md., Mass., Mich., Minn., Mo., Mont., Nebr., N.H., N.J., N.Y., N.C., N.Dak., Ohio, Okla., Oreg., Pa., R.I., Tenn., Tex., Vt., Va., Wash., W.Va., Wis., Europe, sw Asia, also in e Asia (Russian Far East)

Discussion

Subspecies minus is the only member of Chaenorhinum minus to have become widely established as a weed; the other three subspecies occur in Europe, one each in Corsica, Crete, and Turkey.

First collected in Camden, New Jersey (1874), and St. John, New Brunswick (1881), Chaenorhinum minus likely came to North America as a contaminant in ship ballast, with subsequent dispersal along railroad lines (M. P. Widrlechner 1983). R. M. Arnold (1981, 1982) noted that self-compatibility, a short generation time, drought tolerance, and seed dispersal enhanced by passing trains allowed C. minus to be a successful colonizer of railroad rights-of-way, where it was once common but is now scarce because of herbicide use.

Selected References

None.

Lower Taxa

None.
navicular +
Obtuse (?) +  and Acute (?) +
Richard K. Rabeler +  and Craig C. Freeman +
(Linnaeus) Lange in H. M. Willkomm and J. M. C. Lange +
alternate +, opposite +, whorled +, helical +  and subopposite +
tapered +
Antirrhinum minus +
1.5 cm15 mm <br />0.015 m <br /> (3 cm30 mm <br />0.03 m <br />) +
0.4 cm4 mm <br />0.004 m <br /> (0.5 cm5 mm <br />0.005 m <br />) +
0.5 cm5 mm <br />0.005 m <br /> (1.5 cm15 mm <br />0.015 m <br />) +
oblanceolate;lanceolate +
? (?) +  and ? (?) +
1mm;4mm +
0.28 cm2.8 mm <br />0.0028 m <br /> (0.35 cm3.5 mm <br />0.0035 m <br />) +
adaxial +  and abaxial +
accrescent +
0.04 cm0.4 mm <br />4.0e-4 m <br /> (0.08 cm0.8 mm <br />8.0e-4 m <br />) +
urceolate-spreading +
0.4 cm4 mm <br />0.004 m <br /> (0.54 cm5.4 mm <br />0.0054 m <br />) +
glandular-pubescent +
obovoid +  and ellipsoid +
0.2 cm2 mm <br />0.002 m <br /> (0.36 cm3.6 mm <br />0.0036 m <br />) +
personate +  and bilabiate +
white +  and grayish or lilac +
glandular-pubescent +
0.8 cm8 mm <br />0.008 m <br /> (1.1 cm11 mm <br />0.011 m <br />) +
Alta. +, B.C. +, Man. +, N.B. +, Nfld. and Labr. (Nfld.) +, N.W.T. +, N.S. +, Ont. +, P.E.I. +, Que. +, Sask. +, Ala. +, Ark. +, Colo. +, Conn. +, Del. +, Ga. +, Idaho +, Ill. +, Ind. +, Iowa +, Kans. +, Ky. +, La. +, Maine +, Md. +, Mass. +, Mich. +, Minn. +, Mo. +, Mont. +, Nebr. +, N.H. +, N.J. +, N.Y. +, N.C. +, N.Dak. +, Ohio +, Okla. +, Oreg. +, Pa. +, R.I. +, Tenn. +, Tex. +, Vt. +, Va. +, Wash. +, W.Va. +, Wis. +, Europe +, sw Asia +  and also in e Asia (Russian Far East) +
drupe-like +
0–1600 m. +
curved +  and straight +
1 +  and 4 +
Gravelly railroad rights-of-way, road shoulders, urban areas, stream beds. +
alternate +  and opposite +
persistent +  and deciduous +
glandular-pubescent +
narrowly oblanceolate;narrowly lanceolate +
entire +  and subentire toothed or lobed +
axile +  and parietal +
basal +, apical +  and superior +
glandular-pubescent +
tenuinucellate +, unitegmic +  and hemitropous +
campylotropous +, hemianatropous +  and anatropous +
0.5 cm5 mm <br />0.005 m <br /> (2 cm20 mm <br />0.02 m <br />) +
5 +  and 4 +
Flowering May–Oct. +
0.01 cm0.1 mm <br />1.0e-4 m <br /> (0.02 cm0.2 mm <br />2.0e-4 m <br />) +
Prodr. Fl. Hispan. +
minute +
ovoid +  and ellipsoid +
Weedy +, Introduced +  and Illustrated +
unbranched +  and much-branched +
climbing +  and scrambling +
sprawling +, creeping +  and prostrate +
ascending;erect +
8 cm80 mm <br />0.08 m <br /> (28 cm280 mm <br />0.28 m <br />) +
purple spots +
glandular-pubescent +
0.15 cm1.5 mm <br />0.0015 m <br /> (0.2 cm2 mm <br />0.002 m <br />) +
glandular-pubescent +
Chaenorhinum minus subsp. minus +
Chaenorhinum minus +
subspecies +
0.2 cm2 mm <br />0.002 m <br /> (0.3 cm3 mm <br />0.003 m <br />) +
not gibbous +