9.
Thelesperma filifolium
(Hooker) A. Gray, Hooker's J. Bot. Kew Gard. Misc. 1: 252. 1849.
Coreopsis filifolia
Hooker, Bot. Mag. 63: plate 3505. 1836;
Thelesperma filifolium
var.
intermedium
(Rydberg) Shinners;
T. intermedium
Rydberg
Annuals
(sometimes persisting), 10—40(—70+) cm.
Cauline leaves
crowded to ± scattered over proximal
1
/2—
3
/4 of plant heights, internodes mostly 10—35(—50+) mm; lobes mostly linear to filiform, sometimes oblanceolate, 5—30(—55+) × 0.5—1(—3+) mm.
Calyculi
of 7—8+ linear to narrowly triangular bractlets (2—)4—8+ mm.
Ray florets
8; laminae yellow to golden yellow (sometimes proximally suffused with red-brown), 12—20+ mm.
Disc corollas
red-brown or yellow with red-brown nerves, throats shorter than lobes.
Cypselae
3.5—4+ mm;
pappi
0.5—1(—2+) mm.
2
n
= 16, 18.
Flowering Mar—Aug(—Oct). Disturbed sites on clays or sandy soils, rocky slopes, often on limestone; 10—2200 m; Ark., Colo., Kans., La., Miss., Mo., Nebr., N.Mex., Okla., S.Dak., Tex., Wyo.; Mexico (Nuevo León).
As here circumscribed,
Thelesperma filifolium
includes plants that others have treated as a distinct species or variety:
T. intermedium
or
T. filifolium
var.
intermedium
, characterized as plants mostly 10—40 cm (versus taller); internodes "relatively short" (versus longer); calyculus bractlets mostly
1
/4—
1
/2 lengths of phyllaries (versus more than
1
/2 as long); ray corollas yellow (versus "golden yellow"); disc corollas yellow (versus sometimes red-brown); distribution mostly north and west of the typical form (Colorado, Kansas, Nebraska, New Mexico, w Oklahoma, South Dakota, c and w Texas, Wyoming).
According to A. Cronquist (1980),
Thelesperma trifidum
(Poiret) Britton has been misapplied (e.g., M. L. Fernald 1950) to
T. filifolium.
