05 May 2007

A word about tent caterpillars

Forest Tent Caterpillars are unsightly but they are native and therefore have natural enemies here so the worst thing to do is to use insecticides (which would also kill their natural enemies directly or indirectly). While they can cause partial defoliation of some trees (cherries seem to be among their favorites) the trees are not permanently affected and indeed have evolved along with this mild defoliation pressure from these caterpillars. They really should be left alone. They have many natural enemies in the insect world. Caterpillars are frequently parasitized by various tiny braconid, ichneumonid, and chalcid wasps. Several predators and a few diseases also help to regulate their populations. This, in part, accounts for the fluctuating population levels from year to year. Birds and small mammals are known to eat them as well.

If you must get rid of them in your own yard: Remove the egg masses during winter to reduce the problem next spring. In the early spring, small tents can be removed and destroyed by hand. Larger tents may be pruned out and destroyed or removed by winding the nest upon the end of a stick.

For more information

02 May 2007

Time to pull the mustard

Garlic mustard (Alliaria petiolata), that is. This exotic wildflower, introduced to the U.S. from Europe in the late 1800s, is killing our woodlands.

From the New York Times, May 2, 2006:

Researchers have found that it disrupts a healthy relationship between hardwood tree seedlings and soil fungi, with results that can be disastrous for a forest.

Many plants make use of arbuscular mycorrhizal fungi, which form an elaborate network of filaments throughout the soil. These fungi are a diverse group, but they all have one thing in common: they help plants take up nutrients from the soil, getting carbon in return.

Garlic mustard is a member of the mustard family, "one of the very few families that do not need to associate with mycorrhizal fungi at all," Dr. Stinson said. These species produce chemicals that have antifungal properties. Native mustards have been around long enough, she suggested, that the mycorrhizal fungi have learned to live with them. But the fungi haven't had time to adapt to garlic mustard. "It basically is killing off the fungi," she said.

It bullies out our native spring ephemerals, it secretes a compound which destroys the soil fungi that is critical to the survival of our trees, and it fools a native butterfly to lay eggs on it that its the caterpillars can't eat. Here's a primer on the proper protocols for pulling it out. It's a prolific seeder, so bagging it is important.

29 April 2007

Freaky ramps

Today I was back at Corson's Brook Woods in Staten Island for my Torrey plant walk. I came across this: Ramps (Allium tricoccum) with a spooky white stripe. Prematurely grey from worry over site development? The state did want to build on the site. It's actually probably from a virus. I know some plants in the horticultural trade, such as tulips, have viruses introduced to created patterns on petals or leaves.

Gratuitous wildflower photo of downy yellow violet (Viola pubescens).

28 April 2007

Sourland Mountains, NJ

All this rain is ruining my plant walks! I've been looking forward to the Raritain River floodplain walk on Torrey Botanical Society's field trip page. Bluebells, bluebells, and bluebells. They are really just gorgeous. And, for some reason, not in New York. So, I would've gotten my fix if it hadn't rained. And I hadn't gotten lost. Instead, I went to Sourland Mountain Nature Preserve.

Early saxifrage
(Saxifraga virginiensis) on a muddy lump. Note the hairy stems. These sticky stalks protect its precious nectar and pollen from maurading non-pollinators such as ants.

(Obolaria virginica) is an interesting wildflower with its reduced, scale-like leaves. This species is no longer found in NYC.

Emerging rattlesnake fern
(Botrychium virginianum). A persnickety fern, a good indicator of ecological integrity, due to its relationship with mycorrhizal fungi. This species is rare in NYC.
Wild licorice leaves (Galium circaezans)

Jack in the pulpit (Arisaema triphyllum) with deep burgundy stripes on spathe, which acts as an umbrella for the spadix, the actual inflorescence hiding inside which bears tiny blossoms.

27 April 2007

The ways of Callery pear

Callery pear (Pyrus calleryana) planted along Rt 440 in Staten Island.

Callery pear (Pyrus calleryana) planted along Rt 440 in Staten Island.

Callery pear (Pyrus calleryana) volunteering along Rt 440 in Staten Island.

Callery pear (Pyrus calleryana) now found in Conference House Park. That was easy math.

23 April 2007

Corson's Brook Woods 07

Last year was my first time at Corson's Brook Woods, and it made a big impression on me - such a mecca of spring wildflowers! So, I visited again this year and it did not disappoint.

Blue cohosh
(Caulophyllum thalictroides). A striking spring ephemeral, with its unusual flower color and greyish blue glaucous stem. Rare in NYC.

American beech
(Fagus grandifolia). I don't know why, but beech trees hold onto their leaves all winter. They are a welcome splash of color in a winter woodland - and even in spring. Rich forest soils.

Bloodroot (Sanguinaria canadensis). Pure white. Lovely and fleeting. Rare in NYC.

Trout lily (Erythronium americanum). An impressive amount, it just went on and on. These types of shade tolerant species are slow growing, and so such large colonies are very old - the population could've been many decades old.

Virginia waterleaf (Hydrophyllum virginianum). Decorative foliage - the silvery spots that look like water stains. I'm surprised this isn't used more in the hort trade. It's a great groundcover. Found in rich forest soils and floodplains. Rare in NYC.

19 April 2007

Plant Blindness

An excellent overview of the phenomenon - how people don't see plants - from Tuesday's Science Times.

We barely notice plants, can rarely identify them and find them incomparably inert. “Animals are much more vivid to the average person than plants are,” Dr. Raven said, “and some people aren’t even sure that plants are alive.”

*sigh* sadly, it's true. Although, in my experience, people do notice trees, and care a heck of a lot about garden flora.