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cosmos

wild cosmos

Habit Annuals [perennials or subshrubs], 30–250 cm. Plants 30–250 cm, glabrous or sparsely hispid.
Stems

usually 1, erect or ascending, branched distally or ± throughout.

Leaves

mostly cauline; opposite;

petiolate or sessile;

blades usually 1–3-pinnately lobed [undivided], ultimate margins usually entire, faces usually glabrous, sometimes glabrate, hispid, puberulent, or scabridulous.

petioles 1–7 cm;

blades 10–20 cm, ultimate lobes 2–10 mm wide, margins spinulose-ciliate, apices acute, often mucronulate.

Peduncles

10–30 cm.

Involucres

hemispheric or subhemispheric [cylindric], 3–15 mm diam.

5–15 mm diam.

Receptacles

flat, paleate;

paleae falling, linear, flat or slightly concave-convex, scarious (entire).

Ray florets/Ray corollas

[0, 5] 8 (more in “double” cultivars), neuter;

corollas white to pink or purple, or yellow to red-orange.

rose-pink to purple, laminae oblong-oblanceolate, 5–15 mm, apices obtusely 3-lobed.

Disc florets/Disc corollas

10–20[–80+], bisexual, fertile;

corollas yellow [orange] (at least distally), tubes shorter than funnelform throats, lobes 5, ± deltate (staminal filaments hairy near anthers; style branches linear, flattened, thicker distally, hirtellous, appendages relatively slender).

5–6 mm.

Phyllaries

persistent, [5–]8 in ± 2 series, distinct, lanceolate, lance-oblong, lance-ovate, or oblong, ± equal, membranous or herbaceous, margins ± scarious.

erect, oblong-lanceolate, 7–11 mm, apices acute to obtuse.

Calyculi

of [5–]8 basally connate, ± linear to subulate, herbaceous (striate) bractlets.

of usually spreading, linear-subulate bractlets 6–10 mm, apices acuminate.

Heads

radiate, borne singly or in corymbiform arrays.

Cypselae

(dark brown or black) relatively slender, quadrangular-cylindric or -fusiform [outer somewhat obcompressed], sometimes slightly arcuate, attenuate-beaked, not winged [winged], faces glabrous or hispid to scabridulous or ± setose, sometimes papillate, usually with 1 groove;

pappi persistent [falling], of 2–4[–8] retrorsely [antrorsely] barbed awns, sometimes 0.

12–35 mm, glabrous or scabridulous proximally, setose distally;

pappi of 2–3 widely divergent to reflexed awns 3–5 mm.

x

= 12.

2n

= 48.

Cosmos

Cosmos caudatus

Phenology Flowering summer–fall.
Habitat Disturbed sites
Elevation 0–10 m (0–0 ft)
Distribution
from USDA
Tropical and subtropical America; especially Mexico; widely introduced elsewhere
[BONAP county map]
from FNA
FL; Mexico; Central America; South America; West Indies [Introduced in North America; also introduced in Asia, Pacific Islands]
[BONAP county map]
Discussion

Species ca. 26 (4 in the flora).

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Within the flora area, Cosmos caudatus is found only in the Florida Keys.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Key
1. Ray laminae yellow to red-orange
C. sulphureus
1. Ray laminae pink, purple, purplish, rose-pink, violet, or white
→ 2
2. Leaves: ultimate lobes 2–10 mm wide
C. caudatus
2. Leaves: ultimate lobes to 1.5 mm wide
→ 3
3. Ray laminae 15–50 mm
C. bipinnatus
3. Ray laminae 5–9 mm
C. parviflorus
Source FNA vol. 21, p. 203. Author: Robert W. Kiger. FNA vol. 21, p. 204.
Parent taxa Asteraceae > tribe Heliantheae > subtribe Coreopsidinae Asteraceae > tribe Heliantheae > subtribe Coreopsidinae > Cosmos
Sibling taxa
C. bipinnatus, C. parviflorus, C. sulphureus
Subordinate taxa
C. bipinnatus, C. caudatus, C. parviflorus, C. sulphureus
Name authority Cavanilles: Icon. 1: 9, plate 14. (1791) Kunth: in A. von Humboldt et al., Nov. Gen. Sp. 4(fol.): 188. (1818)
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