3. Boltonia diffusa Elliott (doll’s daisy)
B. diffusa var. interior Fernald and Griscom
Pl. 231 a, b;
Map 965
Plants producing
basal offshoots and/or elongate rhizomes. Stems 40–150 cm long. Leaf
blades 2–12 cm long, 2–18 mm wide, those of the lower and
median leaves linear to narrowly lanceolate, those of the upper leaves mostly
linear, the base not decurrent below the attachment point (the stems thus
unwinged). Inflorescences usually not appearing leafy, the relatively few
bracts 0.2–2.5 cm long, 0.5–5.0 mm wide. Heads relatively
small, the receptacle usually 3–6 mm in diameter at flowering. Involucre
2.5–3.5 mm long, the bracts in 3–5(6) more or less unequal
series, narrowly oblong to nearly linear, narrowed or tapered to a sharply
pointed tip or sometimes rounded to an abrupt, short, sharp point. Ray florets
20–50, the corolla 5–8 mm long. Disc florets 55–150.
Pappus of disc florets a short, irregular crown of awns or narrow scales
0.1–0.3 mm long and 2(–4) awns 0.3–0.7 mm long, the
longer awns mostly poorly developed in the disc florets, usually absent in the
ray florets. Fruits 1.5–2.5 mm long, the wings 0.1–0.4 mm wide.
2n=18. July–October.
Uncommon, mostly
in the southeasternmost counties of the Ozark Division and the Mississippi
Lowlands (southeastern U.S. west to Missouri, Oklahoma, and Texas). Banks of
streams and rivers, swamps, sloughs, bottomland prairies, bottomland forests,
and margins of sinkhole ponds; also banks of ditches, roadsides, and moist,
disturbed areas.
This species is
sometimes difficult to distinguish from smaller-headed variants of B.
asteroides. In fact, Morgan (1967) hypothesized that some of the Missouri material represents hybrids between the two taxa, although this has not been
confirmed by further research. Characters that help to differentiate these
species include the apparent leafiness of the inflorescence and the tips of the
involucral bracts. The inflorescences of B. diffusa have few typically
narrow bracts, whereas those of B. asteroides var. recognita tend
to have relatively numerous wider bracts and an overall leafy appearance. The
tips of the involucral bracts of B. diffusa narrow or taper to a sharp
point, but the bracts of B. asteroides var. latisquama are either
rounded or rounded with a short, abrupt point.
Morgan (1967)
recognized three varieties of B. diffusa; however, the new combination
for her var. caroliniana was never validly published. Most botanists
consider this to represent a separate species, B. caroliniana (Walter)
Fernald, which is endemic to the Coastal Plain and Piedmont from South Carolina to Georgia and has achenes that are wingless or nearly so. Morgan followed a
traditional classification in separating the remaining plants into two
varieties that were both attributed to Missouri. The var. diffusa was
said to produce slender rhizomes more frequently, to produce involucral bracts
that are awl-shaped to nearly linear, and to have the stalks of the heads
threadlike, with some of the heads sometimes drooping. In contrast, var. interior
(which occupies parts of the western and northern portion of the species range)
supposedly has a nonrhizomatous habit, involucral bracts that are
linear-oblong, and slender but not threadlike stalks of the heads, with the
heads not drooping. Nearly all of the Missouri specimens are more or less
attributable to var. interior, but two historical collections from
Dunklin and St. Louis Counties appear similar to specimens of var. diffusa
from the southeastern states. In practice, however, many specimens of B.
diffusa are not clearly determinable at the infraspecific level, and there
is more variation in the shapes of involucral bracts than may have been
apparent to earlier workers. The present treatment follows that of Cronquist
(1980) in not formally recognizing varieties within this species.