1. Heliopsis helianthoides (L.) Sweet (oxeye, false sunflower, sunflower heliopsis)
Pl. 283 g–i; Map
1204
Plants perennial
herbs, with fibrous roots and sometimes a short, stout rhizome. Stems 40–150 cm
long, erect or ascending, usually several-branched, with fine longitudinal
lines or ridges, glabrous to sparsely to moderately pubescent with slender,
ascending hairs (these rarely rough to the touch) or more commonly moderately
roughened with short, stout, ascending, broad-based hairs (and sometimes also
scattered, longer hairs). Leaves opposite or the uppermost few alternate,
sessile or relatively short-petiolate, the lowermost leaves sometimes with
longer petioles, the bases minutely expanded and wrapping around the stem
(leaving a low ridge around the stem after the leaves are shed), the petiole
sometimes with sparse to moderate, long, spreading hairs. Leaf blades 3–15 cm long,
oblong-lanceolate to ovate or ovate-triangular, short-tapered or angled to more
or less truncate at the base, tapered to a sharply pointed tip, the margins
sharply and finely to coarsely toothed and minutely hairy, the upper surface
glabrous to minutely pubescent with slender, sometimes broad-based hairs or
more commonly strongly roughened with short, stout, broad-based hairs, the
undersurface glabrous or minutely pubescent with slender hairs (occasionally
with a few longer hairs along the midvein) or more commonly strongly roughened
with short, stout, broad-based hairs, both surfaces also with scattered,
sessile, spherical, yellow glands. Inflorescences of solitary or less commonly
2–4 heads at the branch tips and from the upper leaf axils, the heads usually
with long, bractless, glabrous or roughened stalks. Heads radiate. Involucre
6–16 mm long, 10–22 mm in diameter, cup-shaped to broadly bell-shaped, the
bracts in 2 or 3 subequal series. Involucral bracts 17–29, lanceolate to ovate,
rounded to sharply pointed at the tip, the outer surface usually minutely hairy
or roughened, those of the outer series often somewhat longer than the others
and with loosely ascending to spreading tips, green, those of the inner series
slightly shorter, usually somewhat yellowish green and somewhat scalelike, more
strongly ascending at the tip. Receptacle conical, elongating somewhat as the
fruits mature, with chaffy bracts subtending the ray and disc florets, these
8.0–8.5 mm long, oblong-lanceolate, concave and wrapped around the florets. Ray
florets 8–16(–35), pistillate (with a 2-branched style exserted from the short
tube at flowering), the corolla 15–40 mm long, relatively broad, pale yellow to
orangish yellow, glabrous or nearly so, persistent and turning papery at fruiting.
Disc florets 10–80, perfect, the corolla 4–5 mm long, greenish yellow to
brownish yellow, glabrous, not expanded at the base or persistent at fruiting.
Style branches with the sterile tip somewhat elongate and tapered. Pappus of
the ray and disc florets absent or the disc florets with 2–4 minute teeth.
Fruits 3.0–3.5 mm long, narrowly rectangular to slightly wedge-shaped in
outline, strongly 3-angled (ray florets) or 4-angled (disc florets), the
surface usually appearing finely pebbled, glabrous, dark brown to black,
somewhat shiny. 2n=28. May–September.
Scattered nearly
throughout the state but apparently absent from most of the Mississippi
Lowlands Division (eastern U.S. west to North Dakota and New Mexico; Canada).
Mesic to dry upland forests, savannas, glades, upland prairies, sand prairies,
banks of streams and rivers, seeps, and ledges and tops of bluffs; also margins
of crop fields, pastures, fencerows, railroads, and roadsides.
Oxeye is
sometimes cultivated as an ornamental in gardens. Examination of specimens in
herbaria suggests that many students and botanists have difficulty in
distinguishing this species from some members of Helianthus. This may be
because of difficulties in interpretation of the character of persistent papery
ray corollas. More reliably, the flowering heads of Heliopsis contain
ray florets with a well-developed ovary and an exserted, branched style,
whereas those of Helianthus contain ray florets with a slender,
nonfunctional, stalklike ovary and the style apparently absent (very short,
included in the short, tubular portion of the ray corolla, and undivided at the
tip). The ray florets of Heliopsis develop well-formed, conspicuously
3-angled achenes, whereas in Helianthus the ovary portion of the ray
florets is frequently shed with the corolla or, when persistent, is very
difficult to observe.
Fisher (1957,
1958) treated H. helianthoides as comprising three morphologically
overlapping subspecies with different centers of distribution. In particular,
his ssp. occidentalis and ssp. scabra were noted to intergrade
for most of the characters separating them. In fact, Fisher’s mapped ideograms
representing character coding for features such as petiole length and head
stalk length seem to show a clinal north-to-south variation in the central
portion of the United States with Missouri indicated to occupy part of the main
geographic zone of intermediacy. Other authors, such as Steyermark (1963) and
Turner (1988a), also commented on the large number of specimens intermediate
for one or several of the purported differences between ssp. occidentalis
and ssp. scabra. More recent collections continue to reinforce the
problems in separating Missouri material of these two variants. Accordingly,
they have been reduced to a single taxon in the present treatment. Steyermark
(1963) and Turner (1988a) also chose to treat infraspecific variation within H.
helianthoides at the varietal rather than subspecific level, which seems
reasonable in light of the overlapping ranges of the taxa and the lack of
cytological differences between them.