HGG: Canada St. Johnswort

In today's installment of "Home Grown Greenery" we take a closer look at Hypericum canadense (Canada St. Johnswort). This native species is a member of the Clusiaceae or Mangosteen family. As you may have guessed, this family has its center of diversity in the tropics, with a few genera found in the more temperate climes. In fact, trees & shrubs are the more common plants found in this family, which makes the herbaceous H. canadense all the more intriguing.

Canada St. Johnswort may be an annual or perennial, but is always diminuitive, growing only to 20 inches tall. As with other Hypericum species, its leaves are opposite from each other, & alternate at 12/6 o'clock & 3/9 o'clock. Thus as one looks down the stem from above, they notice a cross pattern. This is the derivation of "St. John" (wort is the Old English word for plant).

From July through September, tiny, 5-petaled, yellow flowers appear on the tips of every stem. If pollinated, fruits develop - dark red conical capsules containing many small seeds.

The best place to find Canada St. Johnswort is in open, sunny, poorly drained areas such as marshes. This particular plant was found in southern Staten Island in an area of sandy glacial outwash with ribbons of clay soils. This plant is rare in NYC, as are its brethren - there are 5 other Hypericum species in the five boroughs, four are native, all are uncommon. One of the biggest threats to its future is the encroachment of trees & shrubs - shaded out by woody species as a result of succession. This is, of course, with the understanding that the biggest threats to our flora are always lack of conservation leadership. NYC natural areas have been destroyed through development & degraded by exotic invasives.

Butterflyweed as cut flowers

I bought this bunch of butterflyweed (Asclepias tuberosa) today at the Greenmarket. Most people think "weeds" when native plants are mentioned, but you have to admit that these are striking.

Jewelweed Runs Amok in England

Jewelweed (Impatiens capensis), native here, invasive abroad.

Our ubiquitous jewelweed is an unwelcome visitor in England. Eric von Wettberg is studying the species genetic bottleneck in its adopted digs. Since a small number of individuals made the initial invasion, he is looking at how the plant has evolved its shade avoidance response (by which plants fit their growth patterns and phenology to maximize their success under a range of light conditions) to fit its new environs.

More on his work

An Alien Invader Spawns a Species

From the Christian Science Monitor:
The influence wrought by invasive species could fuel an "explosion" of ecological change "to levels beyond all expectation."

Why didn't I think of this?

Yes of course! The forest is full of birds! And to think, all these years, I had been assuming that their appetites were sated by the abundant fruits, seeds, & insects that forests naturally provide them. Oh, what a fool I have been!

As seen in Bronx River Park

Organic farms 'best for wildlife'

Organic farms are better for wildlife than those run conventionally, according to a study covering 180 farms from Cornwall to Cumbria.

The organic farms were found to contain 85% more plant species, 33% more bats, 17% more spiders and 5% more birds.

Read article from BBC news

Ultra-violet Flowers

This website is a wonderful introduction to the world according to insects. It is easy for us humans to forget that flowers look as they do not to draw satified sighs from gardeners but to attract potential pollinators - critical to their survival. And what we see is not the whole story.

Here is Pacific silverweed (Potentilla anserina) to humans:










And here is what insects see: