Eupatorium fistulosum Barratt

Authority

Lamont, E. E. 1995. Taxonomy of section (Asteraceae). Mem. New York Bot. Gard. 72: 1-68.

Family

Asteraceae

Scientific Name

Eupatorium fistulosum Barratt

Description

Species Description - Erect herb, 0.6-3.5+ m tall. Stems hollow below inflorescence with a large central cavity, usually evenly purple throughout, sometimes greenish when growing in dense shade, sometimes purple-spotted when young, glandular-puberulent near summit, glabrous below inflorescence (rarely pubescent toward base when young), strongly glaucous throughout (when fresh). Leaves mostly in 4’s-6’s(-7’s); blades narrowly to broadly lanceolate, mostly (8-) 12-25(-28) cm long, (1.5-)2-6(-9) cm wide, gradually tapering to the short-petiolate base, acuminate at the apex, pinnately veined, finely serrate with rounded blunt teeth, usually with a large gland at apex of each marginal tooth, adaxial surface glabrous to sparingly glabrescent, abaxial surface atomiferous and glabrous to sparingly fine-pubescent; petioles usually (0.5-)1-3(-5) cm long, glabrous. Inflorescence a strongly convex, dome-shaped, compound corymbiform cyme (broadly cylindrical when fully developed), its branches diverging abruptly from the stem and then turning upward, usually 10-30(-50) cm high and 10-30 cm wide in life, heads short pedunculate, peduncles conspicuously glandular pubescent. Involucre 6.5-9 mm high, 2.5-5 mm wide, often purplish; bracts 10-22, lanceolate, obtuse at apex, strongly imbricate, few-striate or at least with prominent midvein; receptacle naked, flat or weakly convex. Flowers (4-)5-7 in a head; corolla generally very pale pinkish or purplish, but variable, 4.5-7.5 mm long, funnelform, outer surface usually minutely atomiferous-glandular, 5-toothed, lobes ovate to deltate, usually slightly longer than wide; style base puberulous, enlarged. Achene prismatic, 3.0-4.5 mm long, 5-ribbed, atomiferous-glandular, sometimes with a few setulae along the nerves; pappus a single series of 25-40 slender, capillary, scabrous, persistent bristles. 2n = 20.

Discussion

Type. Without locality, date, and collector’s name (there is only one specimen of E. fistulosum in the herbarium of Barratt according to Grimes & Keller, 1982) (holotype, NY!). Eupatorium laevigatum Torn in Eaton, Man. bot., Ed. 2, 245. 1818 (non Eupatorium laevigatum Lam., Encycl. meth. 408. 1786). Type. Not cited in protologue [holotype, not seen; by description = E. fistulosum (search at NY, NYS, and inquiry to other major herbaria failed to locate the type)]. Eupatorium purpureum var. y angustifolium Torr. & Gray, FI. N. Am. 2: 82. 1841. Type. United States. Tennessee. Without specific locality, s.d., Currey s.n. (there is only one specimen of E. purpureum var. angustifolium from the Torrey Herbarium at NY) (holotype, NY!). Eupatorium fistulosum f. albidum Jennings, Castanea 7: 45. 1942. Type. United States. Pennsylvania. Allegheny Co.: Middle plateau above Wildwood Station, Butler Short Line, 15 Aug 1919, Millward 6247 (holotype, CM!). Eupatorium fistulosum f. truncatum Jennings, Castanea 7: 45. 1942. Type. United States. Pennsylvania. Clarion Co.: Open floodplain field, three miles north of New Bethlehem, 11 Sep 1940, Jennings s.n. (holotype CM!). In the field Eupatorium fistulosum (Figs. 32 & 33) is the most strikingly distinct species of sect. Verticillata. Because of the tall, robust nature of the plants, herbarium voucher specimens do not always document the distinguishing characteristics of this species: height commonly surpassing 2 m, lower stem diameter usually 2 cm or greater, stem strongly glaucous, inflorescence large (commonly 30 cm high, 22 cm wide), leaves commonly 6 or 7 per node. In addition, the upper stem of E. fistulosum is often all that is collected for voucher specimens; although E. fistulosum has a distinctly hollow stem, the uppermost stem directly below the inflorescence is sometimes solid. There has been some confusion concerning the correct authority for E. fistulosum. For example, Jones and Fuller (1955) attributed the name E. fistulosum to Barratt ex Wood; Soil Conservation Service (1982), and Mitchell (1986) attributed the epithet to Barratt ex Hooker. Barratt described E. fistulosum in a single-folio page publication (Fig. 31), titled Eupatoria verticillata, which was distributed among “botanical friends and correspondents” (see Gandhi and Fryxell, 1990). According to Articles 29.1 and 32.1 of the International Code of Botanical Nomenclature (Greuter, 1988) it is evident that Barratt effectively and validly published a new species, and the correct authority for E. fistulosum is Barratt.

Distribution

Habitat and distribution. Predominantly in moist habitats, commonly in open sun or partial shade. Occurring naturally in wet lowlands, especially in alluvial woods, along streams, and in moist meadows, bogs, and marshes that have permanently saturated and seasonally flooded organic soils. Common as a weed along wet roadside ditches and depressions and in moist abandoned fields. From southwestern Maine to Illinois and Missouri, south to northern Florida, and in the west to eastern Texas and Arkan

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