49. Tragopogon L. (goat’s beard)
Plants mostly
biennial herbs (sometimes short-lived perennials), with somewhat fleshy
taproots. Latex white. Stems 1 to several, erect or ascending, unbranched or
more commonly with ascending branches, often hollow (at least toward the tip),
often swollen toward the tip (at least at fruiting), finely ridged, usually
with patches of fine, white, cobwebby to woolly hairs when young, appearing
glabrous or nearly so at maturity, often glaucous, sometimes purplish-tinged or
purplish-mottled around the lower nodes. Leaves basal and alternate, sessile,
the basal leaves sometimes withered at flowering. Leaf blades grasslike,
unlobed, linear from a slightly broadened, more or less rounded base (this
sometimes purplish-tinged), the margins often slightly corrugated or somewhat
incurled and with a narrow, pale band, this often slightly and microscopically
roughened, the surfaces sometimes with small patches of inconspicuous, cobwebby
hairs toward the base when young, appearing glabrous at maturity, usually
glaucous. Venation of few to several apparently parallel main veins, sometimes
the central main vein somewhat thicker than the others, and a sometimes faint
network of anastomosing secondary veins. Heads solitary at the branch tips.
Involucre elongating as the fruits mature, conical to bell-shaped at flowering,
the bracts in 1 series of 8–13, all similar in size and shape (no shorter outer
bracts present), lanceolate to narrowly lanceolate, long-tapered at the tip,
usually with a narrow, pale margin, glabrous or cobwebby-hairy at the base,
sometimes purplish-tinged. Receptacle naked, but often with minute, scaly
ridges between the florets. Ligulate florets 50–180 or more per head. Corollas
yellow or purple. Pappus of numerous plumose bristles, these off-white to
straw-colored or tan to light brown, a few usually distinctly longer than the
rest. Fruits with the body narrowly lanceolate to nearly linear in outline,
often somewhat curved or asymmetrical, tapered to a slender or relatively stout
beak 1–2 times as long as the body (rarely some of the outermost fruits with a
much shorter beak), not or only slightly flattened, with 5–10 nerves or fine,
rounded ribs, the surface with dense tubercles or blunt, ascending barbs,
straw-colored to tan or dark brown (often varying in color in a single head),
the pappus attached to a relatively broad, expanded, disclike tip (except in T.
porrifolius, with a narrow, club-shaped tip), this frequently with woolly
hairs. About 50 species, Europe, Asia, Africa.
Tragopogon defies conventional definitions of the
native vs. nonnative status of species in the North American flora. The three
Old World diploid species in Missouri are widely naturalized in temperate North
America. Where mixed-species populations occur (first studied in the
northwestern United States and not yet noted in Missouri), sterile hybrids are
produced frequently. In several independent cases, two of these hybrids have
regained their fertility through allopolyploidy (doubling of the chromosomes in
an interspecific hybrid), with each tetraploid derivative acting biologically
as a full species. This phenomenon in Tragopogon formed the basis for a
seminal series of studies in plant biosystematics by Marion Ownbey and his
colleagues at Washington State University (Ownbey, 1950; Ownbey and McCollum,
1953, 1954; Belzer and Ownbey, 1971). Since then, Ownbey’s findings on
reticulate evolution in the genus have been confirmed and refined by Pamela and
Douglas Soltis (then at Washington State University) and their colleagues
(Novak et al., 1991; Soltis and Soltis, 1991; Soltis et al., 1995; Cook et al.
1998). Because the two fertile allotetraploid species, T. mirus Ownbey
(derived from past hybridization between T. dubius and T. porrifolius)
and T. miscellus Ownbey (derived from past hybridization between T.
dubius and T. pratensis), have been documented to have evolved
during the twentieth century in the western United States (and apparently have
not formed in Europe), they have been treated by most authors as natives of
North America, even though their progenitors are not native to the continent.
Heads of Tragopogon
species open each morning and, except on cloudy days, generally close by noon.
The plumose pappus bristles tend to intertwine, and when the involucral bracts
become reflexed as the fruits mature, the pappus takes on an intricate globose
shape. These fruiting heads are sometimes carefully dried and then sprayed with
an aerosol resin (to prevent dispersal of the fruits) for use in dried flower
arrangements. Before the heads are produced, plants of Tragopogon might
be confused with some monocot genera such as Tradescantia
(Commelinaceae) or some grasses. However, the grasslike leaves in Tragopogon
do not have sheathing bases as in nearly all monocots.