Download The Tall and The Short of Eupatorium

The Tall and The Short of Eupatorium
The morning mist is slowly rising off of Lake Sagandaga in Hamilton County New York, similar
to what you see in the postcards! Yes, a weekend away from Rutgers Gardens. Surrounded by a
Birch and Hemlock mixed forest, with the lake water gently lapping against the shore stones, it is
only appropriate to consider the garden benefits of our native plants. For the late summer
garden, nothing in my opinion can match the impressive floral color displays of the genus
Eupatorium.
Oddly, this very attractive group of plants is named after a rather ruthless and aggressive King.
Mithridates VI (132BC-63BC) ruled Pontus (now Northern Turkey) and was known as Eupator
Mithridates. Eupator means ‘Of Noble Father’ and it is written that he executed over 80,000
Romans in portions of Asia alone! Mithridites would take sublethal doses of poison in order for
his body to develop resistance to the poison, a practice that became known as Mithridatism.
Eupatorium species typically contain many toxic chemicals; hence it was named in honor of
Eupator Mithridates!
Common to many moist swales and meadows is Eupatorium purpurem, - a six to eight foot tall
plant with purple stems that give rise to the species epithet. Its common name is Joe-Pye Weed.
Joe-Pye was a Native American herbalist that lived during colonial times in the region of
Massachusetts Bay. His cure for easing the pains of Typhoid Fever was E. purpureum. In Late
July through early September, the stems are topped by 8-12” domes of pink flowers that are
highly ornamental and much coveted by butterflies and other pollinators. Its tall height makes it
ideal for use in tall grass meadows or in the border. It is perfectly happy in average garden soil,
as long as it receives full sun. For those seeking plants of more modest heights, selections from
two very similar forms E. purpureum subsp. maculatum ‘Gateway’ and E. dubium ‘Little Joe’
will provide flower heights of 5’ and 4’ tall respectively.
If white flowers are needed, Eupatorium perfoliatum would be of preference. The species
epithet is named after the perfoliate arrangement of the leaves, which have the appearance of the
stem passing or piercing through the leaf. The common name for the plant is Boneset. The
common name is deceiving, since the plant was never used to enhance the healing of bones.
Instead, it was used to remedy the symptoms of Dengue Fever, which is accompanied by severe
joint or bone pain. Aside from the unusual and very attractive leaf arrangement, the plant
produces 4” domes of white flowers in July and August on 3-4’ tall stems. It performs best in
full sun and moisture retentive soils and should be located near a walkway or patio, such that the
unusual details of the foliage can be easily admired.
Ok, perhaps blue flowers are of preference. Eupatorium coelestinum, commonly called Hardy
Ageratum, has beautiful sky blue flowers that appear in late August through early October. The
species epithet of coelestinum is from the Latin, meaning heavenly or celestial in reference to the
flower color. The plant was recently reclassified under the genus Conoclinum (Conoclinum
coelesinum) which more closely relates the plant to the annual Ageratum. Regardless of the
botanical name, Hardy Ageratum is a great addition to the garden. Native to the Eastern half of
North American, I first saw it growing in a boggy estuary in Cape May NJ. The plants grow best
in moist soils and full sun conditions, in which they can occasionally become invasive. In
average garden soil they are typically well behaved, growing to 24” and mix well with
Anemones, autumn blooming Daylilies and Golden Hakone Grass (Hackenochloa macra
‘Aureola).
Eupatorium – or the closely related Conoclinium – are certainly great native choices for the late
summer garden. They provide height, color variety, food for our native pollinators and some
interesting history through their names – key elements for a successful garden!