The fall is like that. All the heat and energy from the summer ends up in stuff we call produce and stuff that botanists call fruit: elderberry, dogwood, viburnum, wild apple, hawthorn, and even herbs like Jack-in-the pulpit (Jill makes the fruit, actually). All of this bursts forth in the middle of September. So why then?

Plants have a few basic reproductive chores to complete each summer. They have to produce flowers, attract pollinators who will actually pollinate, ripen any fruit that start to develop, and then convince some critter to disperse the seed(s) inside the fruit. Dispersal means getting potential offspring elsewhere. If the seeds just drop to the ground, they might end up being next year's pollen donors. That's called inbreeding and, just as with us, the results are not good. If all of this goes according to Hoyle, plants replace themselves with quality offspring, and may even extend their ranges into another patch of appropriate habitat.

From the plants' perspective, there are substantial costs to getting all this done. They make concentrated sugar water for the pollinators, and they make the pulpy tissue that encases the seeds. All of this requires hard-won photosynthate (sugar) that could have been put back into new leaves or sent to the roots to ensure a quick start the next year. For their part, the pollinators and dispersers hate wasting a lot of energy looking for nectar or fruit. It had better be good, or they don't come back. Life is tough.

So what's so magical about early fall? Easy. Migratory birds are moving through, and a lot of fruit-producing shrubs and herbs have to be ready. There is good evidence that the plants time fruit maturation to the peak surge of the moving birds. For example, the shrub species that live both here and in New Jersey stagger their fruiting times, but it's not what you might think. They produce fruit later there than they do here. It should be the other way around--it's warmer there than here, so things ought to ripen earlier. But--you guessed it--the birds that moved through here peak there about a week to ten days later.

Please also remember that the plants have to sink energy into the fruit to attract the birds--the more, the better. Viburnum fruits, for example, can be up to 40% fat. Since fat provides twice as much caloric gain as carbohydrate per unit weight, birds will kill for viburnum fruit. Black, blue, red--it doesn't matter; the birds will find them.  

Winterberry (Ilex verticillata)

By comparison, some fruiting species have "decided" to skimp. The miser in this regard is winterberry. It's a true holly (Ilex) but confuses the issue with its deciduous habit. And just like the evergreen holly down south, winterberry has bright red berries that persist well into winter? Why?

Apparently, the birds mostly ignore them. You can be sure the birds see them, but the fruits are so nutritionally poor that even voracious migratory birds won't eat them. Instead, winterberry is dispersed by hungry mice late in winter, when things get really tough.