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Peruvian zinnia

zinnia

Habit Annuals, mostly 30–50(–100) cm. Annuals or subshrubs [perennials], 10–100(–200+) cm.
Stems

greenish, becoming purplish or yellowish, unbranched or sparingly branched distal to bases, strigose.

prostrate or erect.

Leaves

blades 3–5-nerved, ovate to elliptic or broadly lanceolate, 25–70 × 8–35 mm, scabrellous.

cauline; opposite or subopposite;

sessile [petiolate];

blades (1-, 3-, or 5-nerved from bases) acerose, elliptic, lance-linear, lanceolate, linear, oblong, or ovate, bases rounded to cuneate, margins entire, faces hairy (often scabrous or scabrellous), usually gland-dotted.

Peduncles

10–50(–70) mm.

Involucres

narrowly to broadly campanulate, 9–18 × 10–20 mm.

campanulate, cylindric, to hemispheric or broader, 5–25 mm diam.

Receptacles

conic, paleate (paleae yellowish, often reddish to purplish distally, chartaceous to scarious, conduplicate, apices rounded to acute, sometimes fimbriate).

Ray florets

6–15(–21);

corollas usually scarlet red or maroon, sometimes yellow, laminae linear to spatulate, 8–25 mm.

usually 5–21 (more in “double” cultivars, sometimes 0 in Z. anomala), pistillate, fertile;

corollas yellow, orange, red, maroon, purple, or white (laminae persistent, sessile or nearly so, becoming papery, sometimes much reduced).

Disc florets

12–50;

corollas yellow, 5–6 mm, lobes ca. 1 mm.

20–150+, bisexual, fertile;

corollas usually yellow to reddish, sometimes purple-tinged, tubes much shorter than cylindric throats, lobes 5, lance-ovate (usually unequal, usually villous or velutinous adaxially).

Phyllaries

obovate to oblong, becoming scarious, glabrous, apices rounded, usually entire or erose, sometimes ciliate.

persistent, 12–30+ in 3–4+ series (orbiculate to obovate or oblong, unequal, often colored or dark-banded distally, outer shorter).

Heads

usually radiate (rarely ± discoid in Z. anomala), borne singly.

Cypselae

7–10 mm, 3-angled (ray) or compressed (disc), ribbed, ciliate;

pappi usually of 1 stout awn 4–6 mm (from shoulders of cypselae).

3-angled (ray) or flattened (disc; not winged);

pappi 0, or persistent, of 1–3(–4) awns or toothlike scales.

Paleae

red to purple or yellow, apices obtuse, erose or subentire.

x

= 12 (11, 10).

2n

= 24.

Zinnia peruviana

Zinnia

Phenology Flowering summer–fall.
Habitat Rocky roadsides, ravines, calcareous soils
Elevation 1200–1600 m (3900–5200 ft)
Distribution
from FNA
AZ; FL; GA; NC; SC; Mexico; Central America; South America; West Indies (Hispaniola) [Introduced in Asia (China), South Africa, Australia]
[WildflowerSearch map]
[BONAP county map]
from USDA
United States; Mexico; Central America; South America (one species to Argentina, Bolivia)
[BONAP county map]
Discussion

Zinnia peruviana is presumably native in southern Arizona and reported as naturalized in southeastern United States.

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

Species ca. 17 (5 in the flora).

A. M. Torres (1963) recognized subg. Diplothrix, comprising six species, including the three perennial species treated here, and subg. Zinnia, comprising 11 species, mostly annuals. This division is reflected in the first couplet of the key.

Zinnia angustifolia Kunth (= Z. linearis Bentham), native to northern and western Mexico, is commonly grown as an ornamental in the United States and has been reported from Utah (S. L. Welsh et al. 1993); the record was likely from a cultivated source. The species also persists in gardens in California; it is not known outside of cultivation. It can be distinguished from other zinnias by the combination of annual habit, plants to 50 cm, leaf blades linear to narrowly elliptic (mostly 2–7 cm × 4–8 mm), involucres mostly hemispheric, usually much less than 1 cm high or wide, bright orange ray corollas (white-rayed and other color variants known in cultivation), and lobes of disc flowers glabrous or nearly so. Hybrids between Z. angustifolia and Z. violacea are known in the horticultural trade.

The lack of articulation of the corolla tubes in the ray florets of Zinnia verticillata Andrews (= Z. peruviana) and the bilateral disposition of vascular bundles (continuous with vasculature of the ovary walls) in the ray florets led D. Don (1830) to conclude that true ray “corollas” in Zinnia are lacking, being replaced instead by de novo petaloid structures that mimic ray corollas of other Compositae.

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

Key
1. Annuals, 30–50(–200) cm; leaf blades elliptic, lanceolate, oblong, or ovate; involucres campanulate, or hemispheric or broader, 10–25 mm diam
→ 2
1. Subshrubs, to 22 cm; leaf blades linear to acerose; involucres narrowly campanulate, cylindric, or subhemispheric, 5–10mm diam
→ 3
2. Involucres narrowly to broadly campanulate, 9–18 × 10–20 mm; paleae apically obtuse, erose or subentire; pappi usually of 1 awn (disc cypselae)
Z. peruviana
2. Involucres hemispheric or broader, 10–15 × 15–25 mm; paleae apically fimbriate; pappi 0
Z. violacea
3. Leaf blades 1-nerved, linear to acerose; ray florets 4–7, corollas usually white, sometimes pale yellow
Z. acerosa
3. Leaf blades 1- or 3-nerved (some larger leaves), linear; ray florets usually 5–8, corollas usually yellow (laminae sometimes 0)
→ 4
4. Involucres 8–10 mm; ray laminae 0–6(–9) mm
Z. anomala
4. Involucres 5–8 mm; ray laminae mostly 10–18 mm
Z. grandiflora
Source FNA vol. 21, p. 73. FNA vol. 21, p. 71. Author: Alan R. Smith.
Parent taxa Asteraceae > tribe Heliantheae > subtribe Ecliptinae > Zinnia Asteraceae > tribe Heliantheae > subtribe Ecliptinae
Sibling taxa
Z. acerosa, Z. anomala, Z. grandiflora, Z. violacea
Subordinate taxa
Z. acerosa, Z. anomala, Z. grandiflora, Z. peruviana, Z. violacea
Synonyms Chrysogonum peruvianum, Z. multiflora
Name authority (Linnaeus) Linnaeus: Syst. Nat. ed. 10, 2: 1221. (1759) Linnaeus: Syst. Nat. ed. 10, 2: 1189, 1221, 1377. (1759)
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