Thinking Back (And Ahead) To Warmer Temperatures

Boy, was it cold here yesterday; my car thermometer read 6 degrees Farenheit Saturday morning! The only way for me to get through cold snaps like this in the middle of winter is to look back at photographs I took the previous summer, when the landscape was green and the days were long.


On 11 July 2009, Tony Troche and I spent a couple of hours botanizing at Round Lake Nature Preserve in Starke County, Indiana. Our best botanizing at the preserve came in a rich calcareous wet prairie adjacent to the lake and marsh communities.


Shrubby Cinquefoil (Dasiphora fruticosa), an excellent indicator of calcareous soils, was abundant. Walking was cumbersome in places because of the low shrubby habit of this species and trying to avoid Poison Sumac (Toxicodendron radicans).


Winged Loosestrife (Lythrum alatum), the plant known by Dioscorides as "lytron" (and hence the origin of the genus name Lythrum), was a common forb throughout the wet prairie. This is another species characteristic of wet areas with pH of 7 or greater.


Sedges were common at this location, with one of the more abundante being Dioecious Sedge (Carex sterilis).


An interesting sedge that I have only seen at a handful of locations was White Beaksedge (Rhynchospora alba), a species of acidic and alkaline soils. The white spikelets make this species unique among our beaksedges.


One of our biggest highlights, though, was the highly charismatic Tuberous Grasspink (Calopogon tuberosus). The flowers of most orchid species, including all of them around here except for grasspink, twist when the flower is opening so that the lip is at the bottom, a process known as resupination. In Tuberous Grasspink, the lip is above the rest of the flower.


"No winter lasts forever; no spring skips its turn." -Hal Borland

Purple Loosestrife Biocontrol Update

About a month ago, I blogged about using Galerucella spp. beetles to control Purple Loosestrife (Lythrum salicaria). At that time, Galerucella beetles had just recently emerged, and we saw eggs, larvae, and a few adult beetles, but not much damage to the newly emerged leaves. I visited the same site a few days ago, and the damage to Purple Loosestrife was a much different story.

In the photograph above, you can see what looks somewhat like an herbicided plant. That's Purple Loosestrife after the beetles have done their job. This plant surely won't be producing any seed this year.

The photograph above is a close-up of the damage to Purple Loosestrife leaves.

In the photos above and below, you can see numerous Galerucella beetles covering Purple Loosestrife plants. I counted nine beetles in the photograph below!

There were several comments to my previous post on this topic. We don't know for sure what will happen long-term as a result of the introduction of these beetles. They may feed on our native Winged Loosestrife (Lythrum alatum) and cause similar results to that species. I had suggested that Hybrid Cattail (Typha x glauca) often becomes dominant in areas where Galerucella have been released; I have to correct myself. At these sites, Hybrid Cattail is in fact becoming the dominant in some areas, but native species including Blue Joint Grass (Calamagrostis canadensis), Water Sedge (Carex aquatilis), Jewelweed (Impatiens capensis), and Dotted Smartweed (Polygonum punctatum) are becoming dominant in other areas.

Battling Purple Loosestrife

Purple Loosestrife (Lythrum salicaria) is a perennial herbaceous plant native to Europe and Asia. Many people think this is a "pretty" plant, though to me, it is quite gaudy.
Because of its supposed attractive physical appearance, Purple Loosestrife has been introduced into North America and New Zealand since the 1800s as an ornamental plant. It has since spread to nearly every state in the United States, creating monocultures in wetlands that lead to the exclusion of native plant and wildlife species. It is common in ditches, as seen below, as well as in emergent marshes and sedge meadows, and on pond edges. If you're wondering how a few introduced plants can spread and create such a problem, you will be astounded to hear that a single purple loosestrife plant can produce up to 3 million seeds per year!

In recent years, however, researchers at Cornell University have been studying the natural enemies of this invasive plant in its native range. Where Purple Loosestrife is native, it occurs in small patches, at least in part because it has natural biological enemies; in the absence of these enemies, populations of Purple Loosestrife can run rampant. The researchers have discovered that several beetle species in the genus Galerucella (as well as a few weevil species in the genera Hylobius and Nanophyes) have the ability to keep Purple Loosestrife in check while not impacting other plant species. As these insects reduce populations of Purple Loosestrife, populations of these biological control insects will also decrease. The goal for this method of control is not to completely eliminate Purple Loosestrife, but rather to reduce it to a point that plant and resulting animal diversity can increase.

The photograph below shows eggs of Galerucella sp. on a Purple Loosestrife plant. You may need to click on the photo to increase its size to see the clusters of small cream-colored eggs with hairlike black projections. You'll also notice some damage to the leaves, a result of the introduced insects.
Below is a photograph showing a Galerucella sp. larva, also on a Purple Loosestrife plant. Larvae of these insects are only a few millimeters long.

Finally, the adult stage of Galerucella sp., shown below, on the tip of a Purple Loosestrife leaf.

While botanizing in northern Indiana, I've noticed several places where Galerucella spp. were not introduced but where they are now present, indicating that introduced populations of this biological control agent are spreading to other populations of Purple Loosestrife. Last week, while in Lake Station, I saw the following...

This is definite evidence that the beetles are reproducing, damaging Purple Loosestrife, and spreading to other populations of the invasive plant. Galerucella spp. were introduced at this site, but not in the area of the site where this photograph was taken. Hopefully in a few years, you won't be blinded by the purple haze as you drive through northwest Indiana.