On The Trails: Two little mysteries

Vivid red samaras of a Japanese maple are showy. (Photo by Mary F. Willson)

By Mary F. Willson

One fine, sunny day in mid-July, I strolled around at the Jensen-Olson Arboretum. I usually see something of interest there. I was amused by a sign saying “asparagus” that seemed to guard a large stand of tall foxglove. If I looked closely, however, there really was a delicate sprig of mature asparagus, almost hidden by the leafy foxglove.

Below the vegetable garden, there is a good-sized stand of broad-petaled blue flowers, a domestic variety of geranium. Those flowers (and the neighboring catmint) were notable for the high level of bee activity, not seen on most other flowers that day.  What was so good about those particular flowers?? As I’ve mentioned in previous essays, I am concerned about our bees — I don’t see them much on some species (such as white clover) that are abundant and suitable. I do get occasional reports of very localized activity (e.g., on a patch of orange hawkweed), and now this garden geranium. Such occasional incidents are good, but why are they occasional and isolated?

Along one of the walkways, there is a small Japanese maple with unusual, finely divided leaves. There are many varieties of Japanese maple; this one is a variety called aconitifolium for the supposed resemblance of the leaves to those of monkshood. The tree was bearing paired fruits, each member of the pair with a broad, papery wing. Maple fruits are called samaras, each one holding one seed. They are typically dispersed by wind, with those wings providing lift. These fruits were bright red, unlike the ordinary green of most maples (although there are several species with red samaras, as well as other varieties of Japanese maple). In addition, the fruits were held upright, with the wings flung upward, not hanging down as in other maples. I’ve seen a similar tree at the edge of the parking lot of the Pioneers’ Home.  

A bee alights on a garden geranium just long enough to be photographed. (Photo by Mary F. Willson)

Why does this variety of Japanese maple have red samaras with up-flung wings? It could be a result of domestic breeding programs, mutations deliberately selected by plant breeders to suit their fancy. Or do those features have biological functions? The color may do so, at least in the other species with red samaras.  What about wing orientation — does it affect "flight" as the samara is released from the parent? Or do those up-flung wings turn more downward, in the common orientation, as they mature? Are there natural consequences of the color and wing orientation for Japanese maples?

And here on the home pond, the bunch of eight mallards came through a couple times today. I assume this is the same bunch as before — a female with her seven nearly grown-up kids. They are indistinguishable, except that one of the eight always floats a bit to one side and is noticeably more watchful than the others — so that is Mom.

In the evening, I saw a female standing guard on the bank of the pond, watching over a brood of five tiny ducklings!

Thanks to Ginger Hudson of the arboretum for helpful consultation.

• Mary F. Willson is a retired professor of ecology. "On The Trails" appears periodically in the Juneau Independent. For a complete archive of Mary Willson’s “On the Trails” essays, go to https://onthetrailsjuneau.wordpress.com.