6.
Taraxacum ceratophorum
(Ledebour) de Candolle in A. P. de Candolle and A. L. P. P. de Candolle, Prodr. 7: 146. 1838.
Horned dandelion, pissenlit tuberculé
Leontodon ceratophorus
Ledebour, Icon. Pl. 1: 9, plate 34. 1829;
Taraxacum ambigens
Fernald var.
fultius
Fernald;
T. angulatum
G. E. Haglund;
T. arctogenum
Dahlstedt;
T. brachyceras
Dahlstedt;
T. carthamopsis
A. E. Porsild;
T. coverum
R. Doll;
T. dumetorum
Greene;
T. eriophorum
Rydberg;
T. eurylepium
Dahlstedt;
T. groenlandicum
Dahlstedt;
T. hyperboreum
Dahlstedt;
T. integratiforme
R. Doll;
T. integratum
G. E. Haglund;
T. lacerum
Greene;
T. lateritium
Dahlstedt;
T. longii
Fernald;
T. mackenziense
A. E. Porsild;
T. malteanum
Dahlstedt ex G. E. Haglund;
T. maurolepium
G. E. Haglund;
T. microcerum
R. Doll;
T. ovinum
Greene;
T. pellianum
A. E. Porsild;
T. pseudonorvegicum
Dahlstedt ex G. E. Haglund;
T. umbriniforme
R. Doll;
T. umbrinum
Dahlstedt ex G. E. Haglund
Plants
(1—)6—50 cm; taproots branched.
Stems
1—10+, ascending to erect, ± purplish (at least proximally), densely villous (young) becoming glabrescent, sparsely villous to glabrate or glabrous proximally, ± densely villous distally.
Leaves
± 10, horizontal to patent, sometimes erect; sessile or petioles ± broadly winged (bases barely narrowed compared to blades); blades narrowly oblanceolate to linear-oblanceolate or linear-oblong (often ± runcinate), 4—30 × (0.4—)0.5—5 cm, bases cuneate to attenuate, margins lobed ± deeply to lacerate, irregularly to regularly, often toothed, merely denticulate, or subentire, lobes retrorse, straight or antrorse, deltate to triangular, acute to acuminate, teeth 0—1 on lobes, often more or mostly in sinuses, apices obtuse to sometimes acute, sometimes mucronate, faces glabrous or glabrate to very sparsely villous.
Calyculi
of 12—16(—20), appressed to spreading, pale, ovate to elliptic or lance-ovate to lanceolate (sometimes thin) bractlets in 2—3 series, 5—12 × (0.9—)1.5—5 mm, margins hyaline, white or purplish, scarious, apices caudate to acuminate, ± strongly horned, callous, or occasionally some (rarely all) hornless, tips obtuse to rounded, scarious, erose.
Involucres
dark green, sometimes ± glaucous, campanulate to ± hemispheric, (5—)8—19(—21) mm.
Phyllaries
(10—)12—14(—17) in 2 series, lanceolate to ovate-lanceolate (inner), 1.5—4.5 mm wide, margins scarious or not (outer), inner broadly scarious in proximal
1
/2, apices usually horned, occasionally hornless, horns sometimes exceeding apices, tips white to purplish, scarious, erose.
Florets
40—85+; corollas yellow, drying cream to whitish (outer abaxially gray or purple-striped on drying), 10—22 × 1—2.8 mm.
Cypselae
olivaceous to olive brown, tan to olivaceous tan, brown to reddish brown, grayish brown or straw-colored, bodies oblanceoloid to obovoid, 2.5—4(—5) mm wide, cones conic or narrowly conic to broadly terete, 0.5—0.9 mm, beaks slender, 4.5—14 mm, ribs 5, large (bearing 10—15 narrower ones), faces proximally tuberculate or sometimes nearly smooth (usually with at least some tubercules) to muricate in distal
1
/3—
1
/2, sometimes wholly muricate;
pappi
white to cream, 5—7.5(—8) mm.
2
n
= 16, [24], 32, 40, 48.
Flowering spring—summer. Wet to moist areas, calcareous or igneous rocks, gravel, sand, or clay, wet meadows, shores of streams, sandy or gravelly seashores, seepage slopes, early-melting snowbeds (south); 0—3000 m; Greenland; Alta., B.C., Man, Nfld. and Labr., N.W.T., Nunavut, Ont., Que., Sask., Yukon; Alaska, Calif., Colo., Mont., Nev., N.Mex., Oreg., Utah, Wash., Wyo.; Eurasia.
Taraxacum ceratophorum
is the most widespread native dandelion in North America, ranging from the low Arctic and boreal zone to the western Cordilleras, in the montane and alpine zones.
This complex has been subdivided into many microspecies in North America, most of which appear unworthy of recognition. In the Quebec-Labrador Peninsula,
Taraxacum ceratophorum
grades continuously into what has been called
T. hyperboreum
. Inclusion of
T. hyperboreum
bridges the gap between typical
T. ceratophorum
and
T. lacerum
.
Taraxacum lacerum
stands out by its very lacerate leaves, but intermediates exist and it is impossible to draw a firm boundary. The lacerate Newfoundland form,
T. longii
, may be a spontaneous mutation within the range of
T.
ceratophorum
. If
T. lacerum
were recognized, we would have to place
T. longii
within the former based on leaf morphology, though leaf orientation would be odd there (
T. lacerum
tends to have ascending leaves, and
T. longii
leaves that are flatter on the substrate). A more thorough morphometric and biosystematic study of this complex is warranted. Nonetheless, I have recognized two segregates (
T. laurentianum, T. trigonolobum
) that stand out from the continuum otherwise observed in the complex.
