Ageratina [Eupatorium] aromaticum (Lesser [Smaller] White Snakeroot)

Britton, N.L., and A. Brown. 1913. An illustrated flora of the northern United States, Canada and the British Possessions. 3 vols.Charles Scribner’s Sons, New York. Vol. 3: 362. Provided by Kentucky Native Plant Society. Scanned by Omnitek Inc.

Where Commonly Found:  In dry forest openings, following recent disturbance such as by fire and rocky slopes of southern CT, eastern MA and much of RI, though rare.

How to Identify:  (Note – very similar to the much more common Ageratina altissima)

(For unfamiliar words:  Wikipedia Glossary of Botanical Terms).
Go Botany Key for Ageratina aromatica.
Illinois Wildflower’s description of Ageratina aromatica,  Click on for more images.
Flower Color: White, often fragrant.
Flower Type:  Disk
 without rays, on upper stems terminated in compound corymbs or flat-headed panicles measuring 2″-6″ across, each flower head about 1/2″ across, with 10-19 disk, small tubular, (while A. altissima has 9-34 disks), florets with 5, spreading and pointed, lobes.  Style is divided and exerted well beyond the corolla.  Light green floral bracts at the base of each flowerhead.
Flower Time:  Late summer through early fall, long-lasting blooms.
Leaf Arrangement:  Opposite on occasionally branching stems.  (The stem of A. altissima tend to be much more branched.)
Leaf Type:  Simple, up to 5″ long and 3.5″ across, decreasing in size up the stem.  Leaves are hairless, medium to dark green with 3 prominent veins on the upper surface, particularly the lower leaves, light green on underside.  Margins are strongly serated-crenate.  Lower leaves are cordate to cordate-ovate becoming lanceolate further up the stem.  The petioles are .5″-2.5″ long, generally less than 1/5th the length of the leaf blade (while the petiole of A. altissima can be as much a 1/3 the length of the leaf blade).
Height: 1.5′-3′ tall.
Seed Collection:  AS THIS PLANT IS RARE OR ENDANGERED IN PARTS OF OUR REGION PLEASE FOLLOW GUIDELINES BY THE CENTER FOR PLANT CONSERVATION.  Seeds are thought to be light and wind-dispersed,

Attracts:  Bee and many other insects, unable to find more specific information.
Use:  Woodland Garden
Light:  Full to Part Sun
Hardiness Zone:  4-8  USDA Zone Map
Soils:  Prefers well-drained soils
Notes:  Often consider of medicinal use
Native to: most of eastern MA, southern CT and much of RI, RARE AND/OR ENDANGERED IN CT, NY, RI and native/present in most of the US east of the Mississippi except the northern Midwest.  Biota of North American Program, North American Plant Atlas. 

Requested by Bronx River Wildflower Corridor, Roseanne Andrade.

Reference for differences from A. altissima are from:  Craine, Stephen I., “Ageratina aromatica (L.) Spach Lesser Snakeroot, Conservation and Research Plan for New England”,  prepared for New England Wild Flower Society, 180 Hemenway Road, Framingham, MA 01701.

 

 

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