2.
Tithonia rotundifolia
(Miller) S. F. Blake, Contr. Gray Herb. 52: 41. 1917.
Tagetes rotundifolia
Miller, Gard. Dict. ed. 8, Tagetes no. 4. 1768
Annuals,
mostly 100—200(—400) cm.
Leaves:
petioles 3—8 cm; blades ± deltate to pentagonal, 7—38 × 7—30 cm, sometimes 3- or 5-lobed, abaxial faces glabrous or soft-pubescent.
Peduncles
11—27 cm.
Phyllaries
14—21 in (2—)3 series, lanceolate to linear; outer 17—30 × 4—7.5 mm, apices acute, abaxial faces usually densely puberulent; inner 16—28 × 5—8 mm, apices rounded to acute, abaxial faces usually densely puberulent.
Paleae
11.5—15 × 2—3 mm, mucros 2.5—5.5 mm.
Ray florets
8—13; corollas usually orange, sometimes yellow, laminae oval to oblong, 20—33 × 6—17 mm.
Disc florets
60—90.
Cypselae
5—7.
2
n
= 34.
Flowering Nov.—Jan. Disturbed sites; 0—20+ m; introduced; Fla., La.; Mexico; West Indies; Central America.
Tithonia rotundifolia
is widely cultivated in warm climates and may persist after plantings (e.g., in Asia).
