Fall is the time of fruition, as plants offer their seeds for a coming generation. Winged, fluffed, beaded or barbed, each has a unique beauty — and strategy for dispersal.

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Fall has arrived. And with it, our time of fruition, as plants offer their seeds for a coming generation.

Winged, fluffed, beaded, barbed: Each has a unique beauty — and strategy for dispersal. Some come in a package so delicious, birds and other animals are more than happy to do the distribution work for them.

After all, for the plants that produce them, the flowers and fruits we have enjoyed all summer long are only about one thing: creating the next generation.

A walk through the Washington Park Arboretum now is a revel in the pageantry of seeds just now on offer from both native and exotic plants. In a profusion of colors and forms, some seeds are getting set to fly, float on the wind or water, or hitch a ride on your sock.

“They are so infinite in their variety, and each is a small, perfect package,” said Sarah Reichard, director of the UW Botanic Gardens, which includes the arboretum and the Center for Urban Horticulture.

She pointed to fireweed that seemed to smoke, so thickly flocked were the graceful wands of its branches with the white fluff that will carry its dark seeds on the wind. Tiny as dust, they are tucked in long, slim seed cases beginning to split open.

Horse chestnuts bore their shiny, brown seeds in a space alien’s helmet of a protective cover, green and stuck all over with stiff spines. Golden rain trees were hung with lanterns of dry, papery bladders that hold hard, beadlike brown seeds within. Give the lantern a swish, and the seeds rattle softly.

Most familiar were the helicopter seeds of the maples, with their stiff, winged blades. Even within that family there is variety, with the blades set at different angles.

The red fruits of bittersweet nightshade looked like the tiniest of cherry tomatoes, vivid and succulent, and indeed, tomatoes are in the same family of plants.

Plants use two basic dispersal strategies. One is a very inefficient method of spewing thousands upon thousands of seeds, a blanket-the-world method, in which at least some are bound to land and germinate. Dandelions are proof this is a winning method.

Or, there is the more energy-intensive method of creating wet fruits. It pays off with a more efficient dispersal of seed, complete with the moisture and fertilization packet of an animal’s scat.

Every seed is actually a complete world within a world. Inside the protective seed coat is an embryonic plant, all set to feed off nutritious material packed inside the seed until it can make food with leaves.

Deep within the seed, the embryonic plant is alive and respiring, even when it is not growing but just waiting for the right moisture and temperature to sprout.

Just how long a seed can remain viable continues to surprise even the experts. Reichard recalled a lupine seed estimated to be 10,000 years old that still germinated after it was taken out of a peat bog.

“Each one is a time capsule,” Reichard said of seeds. “And they are extremely resilient.”

Lynda V. Mapes: 206-464-2736 or lmapes@seattletimes.com. On Twitter @lyndavmapes.