When Should Flowers Bloom and Fruits Ripen?

Abstract

In the North Woods of Minnesota, we begin picking juneberries in the middle of July. In slightly warmer climates the berries ripen in June, hence the name, but in colder climates the snow-white flowers of juneberries make a splendid display in late May or early June. The best way to find the ripe berries in July is to make a mental note of where you saw small trees with clouds of white flowers 6 or 7 weeks ago. Some of these trees may be wild plums, but there's a very good chance they will be juneberries. The leaves of juneberry emerge copper orange as the flowers begin to bloom but gradually turn green as the bloom subsides. The spring of 2015 was a banner year for juneberry blooms, the best I've seen in 30 years. Almost everywhere I looked, there was a mosaic of white flowers and coppery leaves against a background of pastel greens emerging from birch and aspen. This spectacular bloom made me realize that there are more juneberries in the forests around here than I had previously thought. Or perhaps the abundance of juneberries has been increasing in the past several decades without me realizing it.

Coevolution of flowering time, pollinators, fruit ripening, and seed dispersers of juneberries.