On The Trails: Summer is here

Beach pea flowers must be manipulated by a bee in order to produce seed. (Photo by Kerry Howard)

By Mary F. Willson

It’s the time when juvenile songbirds appear, fully fledged and flying well: crows, robins, hermit thrushes, juncos, etc. It’s also mosquito season — they found me as soon as I stepped out of the car to walk on the dike trail.

This stroll on the dike trail turned out to be focused primarily on flowers, especially three common, bee-pollinated species. Lupines were blooming vigorously, with many open flowers and buds still to open. The local species has a deep taproot and reportedly does not spread vegetatively. There is little nectar in the flower and pollen is what the bees want to collect. Lupine is said to be self-compatible to some degree, but a bee is needed to open the flower, pushing the side petals outwards, releasing the ‘keel’ formed by two fused lower petals. That’s where the sex organs are, and a bee’s body can contact them (as it collects pollen for its own use); pollen on the bee’s body can be transferred to a stigma or carried to another lupine. The upper petal changes color when the plant has been pollinated, so bees then know to search elsewhere. (However, I’ve seen very few bees on lupine this year, so far). Seeds are dispersed ballistically.

Beach pea bears its dark pink, UV-absorbing flowers on rather short, flexible stems, and the flowers are commonly tucked down in the surrounding vegetation. A visiting bee must push apart the petals to reach the nectar. Pollen accumulates in the "keel" as the flower matures. But the stigma becomes receptive only after its covering is removed by bee activity. Both self-pollen and outcross pollen can fertilize the seeds. This species can spread vegetatively via underground rhizomes that produce multiple flowering stems. The seeds are dispersed when they drop into the water and are carried around by water currents.

Starflower is wide-open, with ready access to insect visitors. (Photo by Mary. F. Willson)

The third common bee-pollinated flower was star flower, a single, white, wide-open flower on a short stem. No tricky entrances, unlike the first two species — all the floral parts are exposed. The flower is reported to be visited by various bees and possibly syrphid flies (although I’ve yet to see insect activity on these flowers). It is self-compatible, but more seed is produced by cross-pollination. Seed dispersal is ballistic, when the tiny seed capsule pops open and the seeds drop out. This species can also spread vegetatively, via underground rhizomes.

A few days later, I walked the Switzer Creek trail with a friend. Star flowers and lupine bloomed here too, and a little stand of iris held one plant with an open flower and several more in bud. For a long time, I avoided this trail because it featured lots of boards that got very wet and slippery.  But lo and behold — those have been replaced by a nice gravel pathway!

Here on the home pond, the mallard sagas continued. As I reported earlier, the first, mixed-sex aggregation was followed by a time when males hung out there, waiting for bereft females to come and get another supply of sperm for a new clutch. But then there came a female with a brood of ducklings. They foraged around the edges of the pond and eventually hauled out on the bank to rest, most of them huddled together under one of mama’s wings. The resident male apparently didn’t like that! He persistently zigzagged back and forth right in front of the resting female, yapping at her. She finally gave up and took her family elsewhere. He reigned supreme for several days. Then the little family came back, very cautiously, at the far end of the pond.

• 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