Tuesday, October 18, 2005

Donna Browne: research on Pulitzer Fountain trees with a PS from Marie

Hi Marie,

One thing leads to another.

So these Lindens are actually Bradford Callery Pears
and White's Sycamores are actually London Planes.

London Planes are a hybrid?

Okay, a hybrid of what? It turns out London Planes
are a fertile hybrid of the American Buttonwood
(Platanus occidentalis) and the Oriental Plane
(Platanus orientalis) introduced from the U.S to
Europe in the 17th century. They came from here? Who

Which led to-Wait a second, I've walked through the
Plaza a lot and I've never seen any pears on these
Bradford Callery Pears. And it's got one of those long

Are they some kind of hybrid as well?

Yup. They are a flowering non-fruiting grafted
hybrid, a supposedly non-invasive cultivar of the Callery
Pear, favored as street trees for their compact
branching pattern. Unfortunately because of their
branching pattern, they have a habit at maturity of
having several big branches crash down at once taking
a chunk of trunk with them. Which rather spoils their
looks. Which led to the development of "new improved"
cultivers of the Callery Pear.

Remember I said the Bradfords were supposedly
non-invasive. Well, unforeseen by most humans, those
old unexpected consequences have reared their heads.
The "new improved" cultivers can cross-pollinate with
the old Bradfords causing them to produce cute little
marble sized fruit. Which the birds eat and then
deposit complete with their own fertilizer all over
the place to grow with abandon, causing these
non-invasives to become invasive.

Like I said, one thing leads to another.


(Though note that the Conservancy has very wisely not
made the mistake of introducing the new cultivers into the park proper,
further adding to the park's problems with invasives.)

PS from Marie:
"Compact branching patterns"? It sounds to me like these trees, though not lindens, share with lindens the feature that a roosting flock would need: thick cover .

PPS Tonight I'm bringing an artist to the Grackle-starling fly-in, to provide some specific names for the changing colors at sunset. More about that later.