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Joe Pye Weed – Native Plant of the Week

Here’s the final installment of our weekly summer highlight of native plants. Thanks to our intern Amalia for her passion on this important topic! -Erica, Horticulture Educator

If you’ve ever seen hazy-pink flowers on a tall stem beside a North Country road or stream around this time of year, chances are that it was Joe Pye weed or a close relative. While often thought of as a wetland plant, several species are highly heat and drought tolerant, making them suitable for a variety of landscapes. Joe Pye weeds are scientifically known as the genus Eutrochium, which consists of five species, all native to North America. Its often-confused sister genus, Eupatorium, by contrast, encompasses hundreds of species across multiple continents. Let’s explore the distinction between these two genera, and what makes Joe Pye weed special! 

First some history: Once upon a time, all these plants were lumped together under the genus Eupatorium, and commonly as the bonesets, thoroughworts, snakeroots, and more. Most of these plants have white flowers and leaves that occur in opposite pairs, while the Joe Pye weeds have pink or purplish blooms and grow whorls of three to six leaves along their stems. 

The name Joe Pye weed is thought to come from a prominent Mohican leader, Joseph Shauquethqueat, often referenced in historical documentation with the surname Pye, who lived in colonial-era New England. He, or others using the name ‘Joe Pye’ (with various spellings) have sometimes been attributed with using the plant in question to treat typhoid fever and other ailments, though there is very little specific evidence for this. 

In the early 19th century, the eccentric but instrumental French-American naturalist Constantine Samuel Rafinesque was the first to propose separating Joe Pye weeds, scientifically speaking, from other members of Eupatorium, and gave them the name Eutrochium. This did not catch on, however, and in 1970, research botanists Robert M. King and Harold Robinson, unaware of Rafinesque’s proposal, suggested the same grouping change but gave their new genus the name Eupatoriadelphus. That name was then widely accepted and started gaining popular usage. In 1987, though, King and Robinson acknowledged their Eupatoriadelphus to be the same group that Rafinesque had described, but nonetheless decided to regroup them under Eupatorium. Following further research published in 1999 and 2004, including DNA analysis, the Joe Pye weeds were once again split off from Eupatorium, and the small genus finally became formally known as Eutrochium. 

To keep things muddled, some nurseries and informational sources continue to use any of the three genus names to refer to Joe Pye weed, as well as perpetuating confusion between a few of its species. You may therefore still find Joe Pye weed advertised or discussed with the name Eupatorium or Eupatoriadelphus; just be aware that Eutrochium is the most current and accurate name for it. 

Four of the five Eutrochium species are popular landscape plants throughout North America and Western Europe. The exception is E. steelei or Steele’s Joe Pye weed, which grows almost exclusively in the Southern Appalachian region at a specific elevation. 

Coastal plain Joe Pye weed, E. dubium, also has a fairly narrow native range along the eastern U.S. coast, but has become widely popular as a landscape plant due to its relatively smaller size (typically less than 5 feet tall), very good heat and drought tolerance, and moderate salt resistance. 

Pink flowers, like others featured but more compact
Eutrochium dubium (photograph by David J. Stang, distributed under a CC BY-SA 4.0 license)

Eutrochium dubium and the other three species not yet mentioned are all native to various parts of New York State, but only two are present in St. Lawrence County – Eutrochium maculatum or spotted Joe Pye weed, and Eutrochium purpureum or purple Joe Pye weed. The other is E. fistulosum, with common names trumpetweed or hollow Joe Pye weed. In the wild, E. fistulosum is a generalist wetland plant, and can grow to a gigantic 6 to 10 feet in height. In a garden setting, though, it will typically stay a more manageable size, and is very heat and drought tolerant. It’s native to a few counties scattered across New York State, but is not recorded as present here in St. Lawrence County. Read more Joe Pye Weed – Native Plant of the Week

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Goldenrod – Native plant of the week

Goldenrods, or members of the genus Solidago, are a truly essential part of our native landscapes, and suffer from some common misconceptions. This week, we’ll look at why goldenrod is so important, clear up those myths, and check out some common species you can cultivate – to help native pollinators, and for your own enjoyment! 

First of all, about that pesky myth: that goldenrod pollen causes allergies.  

In fact, the plant primarily responsible for those seasonal allergies, sometimes called hay fever,  is ragweed. Ragweed is pollinated by wind rather than insects, so it has tiny inconspicuous flowers that produce copious amounts of extremely fine pollen, which then drifts through the air in hopes of landing on other ragweed flowers – irritating the respiratory systems of unfortunate humans along the way. Goldenrod, on the other hand, is pollinated by insects, so it produces heavy, sticky pollen to attract and nourish them. The insects pick up some of the pollen when they visit to eat it or drink the flower’s nectar, and then transport it to the next flower they stop at – hopefully another goldenrod plant. This pollen never becomes airborne (unless perhaps you bump into or shake the plant, in which case some might fall to the ground), and therefore does not cause allergies. 

Ragweed on the left, compared to goldenrod on the right
Ragweed is on the left, and goldenrod is on the right.

How did this get mixed up? While the two plants look very little alike, it probably stems from the fact that they bloom around the same time. Since people don’t notice the flowers of ragweed, they probably see the shaggy, bright yellow (pollen-colored) blooms of goldenrod, and assume that it must be the source of their suffering – then spread this mistaken assumption around. This unfortunately discourages some people from cultivating goldenrod.  

Goldenrod is an extremely valuable plant to pollinators and other insects. It is a keystone species in many North American ecosystems – meaning so many other species depend on it that if it was removed the entire system would change drastically. In goldenrod’s case, this is mostly because so many things like to eat it: around 130 species of lepidopterans (butterflies and moths) use it to host their larvae, just in our area! Plants in the Solidago genus are the only host for many of those species. These butterflies and moths are not only pretty, and important pollinators themselves, but both larvae and adults are also crucial food sources for many species of birds, especially for parents trying to feed their young. 

A few of the species that solely rely on goldenrod are the Asteroid Moth or Goldenrod Hooded Owlet (Cucullia asteroides), the Diamond Spot Pearl or Beet Webworm (Loxostege sticticalis), the Bilobed Dichomeris Moth (Dichomeris bilobella), and the Confused Eusarca (Eusarca confusaria).

Three beige moths
Top left: Eusarca confusaria (photograph by Andy Reago & Chrissy McClarren, distributed under a CC BY 2.0 license). Bottom left: Loxostege sticticalis (photograph by Marcello Consolo, distributed under a CC BY-NC-SA 2.0 license). Right: Cucullia asteroides (photograph by Andy Reago & Chrissy McClarren, distributed under a CC BY 2.0 license).

Aside from hosting the larvae of so many insects, one of the most important roles goldenrod plays is providing abundant nectar and pollen to feed pollinators in the late summer and fall. When many other flowers are slowing down and ending their blooming season, goldenrod fills in as a primary food source for these insects and other animals. This is especially crucial to migratory butterflies like Monarchs, which rely on this plentiful, easy-to-find nectar during their flight south in the fall.  Read more Goldenrod – Native plant of the week

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Heat and Garden Vegetables

Near record breaking heat will have an impact on our garden’s vegetables.  In general, daytime temperatures that exceed 92°F and nighttime temperatures above 72F will cause problems.  The longer the heat lasts, the bigger the impact. Problems include:

Sunscald – Usually a problem with late season heat waves when loss of foliage is more prevalent, but any fruit exposed to direct sunlight can experience bleaching and browning of the exposed parts.

White spot on a green tomato
This tomato shows classic sunscald. Photo credit: Flickr

Pollination issues in cucurbits – Heat favors male flower production over female flowers, resulting in fewer fruits, at least temporarily.  It may also lead to drop of already set fruit.  Bee flights/activity is reduced in hot weather which causes poor pollination and flower drop.  In some cases, fruit will be distorted and crooked due to incomplete pollination. Cucumbers are especially sensitive to this disorder.

Tomato/Pepper flower drop – Flowers on these plants have a 48-hour window to pollinate.  High temperatures can cause pollen sterility and flower drop.  You may not notice the impact until 5 to 6 weeks later when yields are suddenly reduced for a period that aligns with the length of the heat wave.

Sweet corn yields – Although a heat loving crop, daytime temps over 95F can result in poor tip fill, missing kernels, smaller ears, and reduced yield.

Snap bean flower drop – Beans respond by dropping flowers.  As soon as temperatures cool down, flowers will develop normally.  Unfortunately, this may result in a split set, where some flowers set before the heat and others after. This is a big problem for one-time mechanical harvest but doesn’t have much impact on garden grown beans. Read more Heat and Garden Vegetables