Arb Sightings 10/22/10

Posted on October 22nd, 2010 by

What a pleasant week of October-like weather we have had here in southern Minnesota! High temperatures have remained in the 50’s to low 60’s (with the exception of today, which might reach the low 70’s), and we’ve seen nothing but sun all week. The winds however began to increase around mid-week, and after this brief warm front today rain showers are on the weekend’s horizon. Following a few days of precipitation, temperatures will get a bit cooler next week and we should see a few frosty mornings here in St. Peter.

The scenery here in the Linnaeus Arboretum looks a bit conflicted this week. Many of our deciduous trees have dropped all their leaves, but many others still are holding on to most of theirs. What’s perhaps even more impressive is that some other trees aren’t even showing fall colors yet, but rather appear as green as they did a month ago. And it’s not just a difference between species; indeed, individuals of the same species are appearing in stark contrast to each other. This happens to some extent each fall, but the unusually warm weather we’ve experienced this month seems to have accentuated this difference. For example, in an “ordinary” October, all of our sugar maples will generally begin changing color around the same time, resulting in a “peak week” of maple color. This October, many of our sugar maples reached peak color a couple weeks ago and are now bare of foliage, yet many others have yet to show any signs of yellowing! Extrapolating this observation to other species, one can visualize the offset pattern of senescence (biological change) we’re seeing this fall.

Here are some other highlights from this week in the Arb:

– ‘Stella d’Oro’ Daylilies still blooming in perennial gardens behind Interpretive Center 10/22

– Hundreds of Cedar Waxwings feeding on crabapples throughout Arb and across campus 10/19-21

– Tamaracks beginning to show a hint of fall color 10/20; on this date last year these trees were showing peak fall color

– Painted Lady, Red Admiral, and Clouded Sulphur nectaring on New England Aster in Thornberg Garden on east side of Interpretive Center 10/19

– Small flock of Hermit Thrushes foraging in deciduous woods south of Jones Northern Forest Ponds 10/18

– ‘Heavy Metal’ Miscanthus grass (often called “Japanese Silver Grass”) in full bloom in Evelyn Young Gardens behind Interpretive Center 10/18

'Heavy Metal' Miscanthus in full bloom in Evelyn Young Gardens, 10/18/10.


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