Eupatorium polyodon Urb.

• Title

  Eupatorium polyodon Urb.

• Authors

  Nathaniel Lord Britton, Frances W. Horne

• Scientific Name

  Eupatorium polyodon Urb.

• Description

  Flora Borinqueña Eupatorium polyodon Rough Eupatorium Family Carduaceae Thistle Family Eupatorium polyodon Urban, Symbolae Antillanae 1: 462. 1899. Ignatius Urban, who first recognized this endemic shrub of Porto Rico as different from all others, was an eminent German botanist, who lived from 1848 to 1931. He made noteworthy contributions to knowledge of West Indian Botany, in many publications; his "Symbolae Antillanae" appearing in 9, thick, octavo volumes, each of 4 parts, from 1896 to 1928, contains descriptions of many Porto Rican plants new to Science, among them the one here illustrated, which had previously been erroneously regarded by Bello as identical with Eupatorium cordifolium Swartz, native of Jamaica, and by Doctor Stahl as the same as Eupatorium triste, also endemic in Jamaica. The shrub is frequent or occasional in moist districts, inhabiting thickets and woodlands, ascending to at least 700 meters elevation, and most abundant at high altitudes. An account of the genus Eupatorium may be found with our description of Eupatorium resinifluum. Eupatorium polyodon (many-toothed) is a shrub recorded as reaching 6 meters in height, but it is usually lower. The twigs are finely hairy and rough. The ovate to elliptic, thick, pointed, 3-nerved leaves are from 4 to 11 centimeters long, with a somewhat heart-shaped base, and toothed margins, the upper surface rough, the under side glandular, and hairy on the veins; their stout stalks are from 5 to 15 millimeters long. The flower-heads are numerous in loose, broad clusters, the flowers white or rose; the involucre is about 4 millimeters long, its narrow, hairy bracts in 2 series. The 5-ribbed achenes are smooth, but slightly glandular.