Sunflower-Helianthus annuus L.-Poisonous plant

Sunflower

Synonyms: Helianthus aridus, H. lenticularis

Other names:

Common Sunflower, Wild Sunflower.

General poisoning notes:

Sunflower (Helianthus annuus) causes allergic contact dermatitis in sensitive individuals after contact with the sesquiterpene lactones contained in fragile, multicellular, capitate glandular hairs (Hausen and Spring 1989). Cattle have been poisoned in Europe after ingesting plants that did not have mature seeds. This is a result of nitrate toxicity, which has caused sickness and death (Cooper and Johnson 1984).

Description:

Annuals, 100–300 cm. Stems erect, usually hispid. Leaves mostly cauline; mostly alternate; petioles 2–20 cm; blades lance-ovate to ovate, 10–40 × 5–40 cm, bases cuneate to subcordate or cordate, margins serrate, abaxial faces usually ± hispid, sometimes gland-dotted . Heads 1–9. Peduncles 2–20 cm. Involucres hemispheric or broader, 15–40(–200+) mm diam. Phyllaries 20–30(–100+), ovate to lance-ovate, 13–25 × (3–)5–8 mm, (margins usually ciliate) apices abruptly narrowed, long-acuminate, abaxial faces usually hirsute to hispid, rarely glabrate or glabrous, usually gland-dotted. Paleae 9–11 mm, 3-toothed (middle teeth long-acuminate, glabrous or hispid). Ray florets (13–)17–30(–100+); laminae 25–50 mm. Disc florets 150+(–1000+); corollas 5–8 mm (throats ± bulbous at bases), lobes usually reddish, sometimes yellow ; anthers brownish to black, appendages yellow or dark (style branches yellow) . Cypselae (3–)4–5(–15) mm, glabrate ; pappi of 2 lanceolate scales 2–3.5 mm plus 0–4 obtuse scales 0.5–1 mm. 2n = 34.

Nomenclature:

Scientific Name: Helianthus annuus L.

Vernacular name(s): sunflower

Scientific family name: Compositae

Vernacular family name: composite

Geographic Information

Helianthus annuus is widely distributed, including weedy, cultivated, and escaped plants. It is the only native North American species to become a major agronomic crop. Despite its considerable variability, attempts have failed to produce a widely adopted infraspecific system of classification. Forms with red-colored ray laminae, known from cultivation and occasionally seen escaped, trace their ancestry to a single original mutant plant. It hybridizes with many of the other annual species.

Toxic parts:

Hairs.

Notes on Toxic plant chemicals:

Sunflower contains several sesquiterpene lactones, including the most active chemical, 1-O-methyl-4,5-dihydroniveusin A, in the hemiketal form. The complete mixture of sesquiterpene lactones contributes to the allergic response in humans. These chemicals are found in the capitate glands on sunflower leaves (Hausen and Spring 1989). Sunflowers can also accumulate toxic amounts of nitrates, which have poisoned cattle in Europe (Cooper and Johnson 1984).

Toxic plant chemicals:

Dihydroniveusin A, nitrate.

Animals/Human Poisoning:

Note: When an animal is listed without additional information, the literature (as of 1993) contained no detailed explanation.

Cattle

General symptoms of poisoning:

Agitation, collapse, death,lungs, congestion of.

Notes on poisoning:

Cattle that ingest sunflower plants that have not formed mature seeds develop nitrate poisoning. Symptoms include circulatory failure, swaying of hind quarters, excitation, and collapse 1-3 h after ingestion. Postmortem findings include lung edema, small hemorrhages and congestion of intestinal blood vessels, and dark- colored blood (Cooper and Johnson 1984).

Humans

General symptoms of poisoning:

Eczema, erythema.