Cosmos caudatus Kunth

• Title

  Cosmos caudatus Kunth

• Authors

  Nathaniel Lord Britton, Frances W. Horne

• Scientific Name

  Cosmos caudatus Kunth

• Description

  Flora Borinqueña Cosmos caudatus Clavel Wild Cosmos Family Carduaceae Thistle Family Cosmos caudatus Humboldt, Bonpland and Kunth, Nova Genera et Species Plantarum 4: 240. 1820. Bidens Berteriana Sprengel, Systema Vegetabilium 3: 454. 1826. Attractive by its rose-colored flowers, this slender, upright, cut-leaved, perennial herb is frequent on banks and in fields at lower and middle altitudes in Porto Rico, most abundant in moist or wet districts, ranging from sea-level to at least 600 meters elevation, and grows also on Vieques Island. Its natural distribution is nearly throughout the West Indies, except the Bahamas, in Florida, and from northern Mexico to Peru and Brazil; it is the only species of its genus growing wild in Porto Rico. Spanish Needles is another popular name. Cosmos is a genus established by the Spanish botanist Cavanilles in 1791, and comprises some 12 species of herbaceous plants, all natives of tropical America; some botanical authors have classified them as species of Bidens, which they resemble, but the fruits (achenes) of Bidens species are beakless, those of Cosmos beaked. They have opposite, mostly divided leaves and long-stalked heads of flowers, the involucre composed of small bracts in 2 series. The ray-flowers, rose-colored in the native species here illustrated, do not form fruit, but the disk-flowers, yellow or yellowish, are perfect and fertile. The slender, distinctly beaked achenes bear 2 or several retrorsely barbed or hispid bristles (awns). Cosmos caudatus (tailed) grows from 0.5 to 2 meters high, often much branched, with nearly upright, sparingly hairy branches. The thin, long-stalked leaves are twice divided, into ovate or lance-shaped, pointed segments, the lower leaves about 15 centimeters long, or shorter, their stalks hairy-margined. The involucre, of the flower-head is from 12 to 15 millimeters high, its outer, long-pointed bracts narrower than the inner ones; the rays are from1 to 2 centimeters long. The achenes are from 10 to 15 millimeters long, narrowed upward into a slender, upwardly barbed beak as long as the body or longer; the 2 pappus-awns are 2 or 3 millimeters long. The Mexican Cosmos sulphureus, Panchitas, or Yellow Cosmos, with bright yellow ray-flowers, is often grown in flower-gardens.