5.
Helenium flexuosum
Rafinesque, New Fl. 4: 81. 1838.
Purplehead sneezeweed, hélénie nudiflore
Helenium nudiflorum
Nuttall
Perennials,
30—100 cm.
Stems
usually 1, usually branched distally, strongly winged, glabrous or sparsely hairy proximally, sparsely to moderately hairy distally.
Leaves
glabrous or sparsely to moderately hairy; basal blades oblanceolate to obovate or spatulate, entire or serrate; proximal and mid blades oblanceolate to lanceolate, entire or toothed; distal blades lanceolate to lance-linear, entire.
Heads
(1—)5—50(—80+) per plant, in paniculiform arrays.
Peduncles
3—10 cm, sparsely to moderately hairy.
Involucres
globoid to usually ovoid, 8—17 × 9—17 mm.
Phyllaries
(connate proximally) moderately to densely hairy.
Ray florets
usually 8—13, neuter, sometimes 0; corollas yellow to reddish brown to red to purple, 10—20 × 5—10 mm.
Disc florets
250—500(—700+); corollas yellow proximally and purple distally or purple throughout, 2.3—3.7 mm, lobes 4(—5).
Cypselae
1—1.2 mm, moderately hairy;
pappi
of 5—6 entire, aristate scales 0.6—1(—1.7) mm.
2
n
= 28.
Flowering (Apr—)May—Jul(—Oct). Ditches, fields, washes, along streams; 10—900 m; N.S., Ont., Que.; Ala., Ark., Fla., Ga., Ill., Ind., Ky., La., Md., Mass., Mich., Miss., Mo., N.J., N.C., Ohio, Okla., Pa., S.C., Tenn., Tex., Va., W.Va., Wis.
It has been suggested that
Helenium flexuosum
may be of hybrid origin from
H. campestre
(perennial, 2
n
= 28) and some member of
Helenium
sect.
Tetrodus
(H. F. L. Rock 1957). The only member of sect.
Tetrodus
that has a chromosome number of 2
n
= 28 is
H. linifolium
, an annual from southern Texas.
