1.
Doellingeria umbellata
(Miller) Nees, Gen. Sp. Aster. 178. 1832.
Tall flat-topped white aster, parasol whitetop, aster à ombelle
Aster umbellatus
Miller, Gard. Dict. ed. 8, Aster no. 22. 1768;
Diplopappus umbellatus
(Miller) Hooker;
Diplostephium umbellatum
(Miller) Cassini
Plants
50—200 cm (short to long-rhizomatous, sometime colonial).
Stems
1—10(—20), ascending to erect, striate, glabrous or sparsely hairy.
Cauline leaves:
mid and distal crowded, blades broadly to narrowly elliptic, (35—)60—110(—150) × (5—) 13—25(—35) mm, ± reduced distally, not stiff, bases attenuate, margins entire, involute, finely ciliate, apices acuminate, faces glabrous or sparsely hairy, especially along veins abaxially, or densely hairy.
Heads
(3—)20—100(—300+).
Peduncles
1—10 mm, moderately to densely canescent; bracts linear-lanceolate to elliptic.
Involucres
3—5 mm.
Phyllaries
in 3—4 series, triangular-lanceolate, midveins not swollen, apices finely subulate, strigose.
Rays
(2—)5—10(—16); laminae (4—)7—10(—12.3) × (0.8—) 1.2—1.8(—2.7) mm.
Disc florets
(5—)11—26(—50); corollas 3.5—6 mm, lobes 2—3.2 mm, 60—75% of limb.
Cypselae
1.4—3.2 mm, 4—6-ribbed, sparsely to densely strigose;
pappi:
outer 0.2—0.8 mm, inner 3.5—6.2 mm.
2
n
= 18.
Varieties 2 (2 in the flora): e North America.
