Eupatorium resinifluum Urb.

• Title

  Eupatorium resinifluum Urb.

• Authors

  Nathaniel Lord Britton, Frances W. Horne

• Scientific Name

  Eupatorium resinifluum Urb.

• Description

  Flora Borinqueña Eupatorium resinifluum Resinous Eupatorium Guerrero Family Carduaceae Thistle Family Eupatorium resinifluum Urban, Symbolae Antillanae 1: 461. 1899. Remarkable for the abundant resinous secretion by its foliage, which causes it to adhere to paper in drying, this viscid shrub grows at middle or higher elevation in moist parts of central and western Porto Rico, where it is endemic and locally abundant on hillsides; the resin appears to be very characteristic, and in so far as we know its chemical composition has not been studied. Four other Eupatoriums are native in Porto Rico, and another, native of continental tropical America, is cultivated, for use as a febrifuge, and is occasionally seen as an escape from gardens in the mountains. The derivation of the generic name, adopted by Linnaeus, is from Mithridates Eupator, signifying "from a noble father"; he knew 14 species in 1753, but the number existing is now known to be over 500, this being one of the largest genera of plants; they are distributed over all temperate and tropical regions, mostly herbs and shrubs, but a few are trees. In most kinds the leaves are opposite; the small, white, blue or purple often fragrant flowers are in numerous clustered heads borne at the ends of the branches, the plants often conspicuous and attractive while in bloom; the heads of flowers have an involucre of very small bracts imbricated in from 1 to 3 series; the corollas are regularly 5-toothed; the minute, 1-seeded, 5-angled, dry fruits (achenes), bear a tuft of capillary bristles (pappus), white or brownish, often conspicuous through abundance and widely scattered by the wind. Eupatorium resinifluum (flowing resin) is a branched shrub from 1 to 2 meters high, its leaves and round twigs smooth or nearly so; it is commonly gregarious in colonies. The lance-shaped leaves are rather firm in texture, pointed or blunted, quite prominently veined, from 4 to 12 centimeters long, about 4 centimeters wide, or narrower, with toothed margins; their stalks are from 4 to 12 millimeters long. The clusters of heads are about 8 centimeters broad, or less, the heads numerous, each containing a few, white flowers; their involucres are about 5 millimeters high, composed of 5 or 6 bracts arranged in one series. The achenes are minutely rough-hairy on the margins. The flowers of this shrub are pleasingly fragrant; Mrs. Horne noted that the odor resembles that of the Sweet-fern of the northeastern States.