6. Rudbeckia maxima Nutt. (great coneflower, cabbage coneflower)
Pl. 287 a; Map
1222
Plants
perennial, with rhizomes. Stems (60–)80–250 cm long, glabrous, glaucous. Leaves
all unlobed, all except the basal and lower stem leaves rounded to shallowly
and somewhat obliquely cordate at the base, more or less clasping the stem, the
margins entire or shallowly scalloped to bluntly toothed, the surfaces
glabrous, smooth, strongly glaucous, appearing gray to bluish green when fresh.
Basal and lowermost stem leaves often present at flowering, usually
long-petiolate, the blade 10–35 cm long, 40–120 mm wide, narrowly obovate to
broadly elliptic or broadly elliptic-obovate, rounded to sharply pointed at the
tip. Median and upper stem leaves sessile, the blade 3–20 cm long, 20–150 mm
wide, broadly oblong-ovate to oblong-circular, the uppermost sometimes ovate,
abruptly tapered to a bluntly or sharply pointed tip. Inflorescences mostly
appearing as solitary heads, sometimes 2- or 3-headed open clusters. Involucral
bracts 12–20, 8–22 mm long, narrowly ovate to lanceolate or narrowly
oblong-lanceolate, usually glabrous and somewhat glaucous, the margins
sometimes slightly thickened and yellowish. Receptacle 35–80 mm long, 15–35 mm
in diameter, ovoid at the start of flowering, then elongating and becoming
conical or somewhat cylindrical. Chaffy bracts subtending only the disc
florets, shorter than the disc florets, rounded or broadly angled to a bluntly
or sharply pointed tip, the outer surface mostly moderately to densely
pubescent with short, tan hairs but glabrous at the tip, the margins similarly
hairy but glabrous toward the tip. Ray florets 10–21, the corolla 30–80 mm
long, relatively broad, reflexed or strongly drooping at flowering, yellow, the
outer surface sparsely short-hairy to nearly glabrous. Disc florets numerous,
the corolla 4–6 mm long, greenish yellow to yellow toward the base, dark purple
to purplish brown toward the tip, the lobes ascending at flowering. Stigma
lobes relatively short and rounded to bluntly pointed at the tip. Pappus of 4–6
scales 0.8–1.8 mm long. Fruits 5–7 mm long. 2n=36. July–August.
Introduced,
known thus far only from historical collections from Jackson County (Texas to
Louisiana north to Oklahoma and Arkansas; introduced in Missouri and South
Carolina). Habitat unknown, but according to Steyermark (1963) railroads.
This species is
occasionally cultivated as an ornamental in gardens for its striking grayish foliage
and large heads. Cox and Urbatsch (1994) noted that in Texas the plants can
become aggressive pasture weeds and that cattle avoid grazing on them.