Wildflowers of the Westborough Reservoir

Late July

Wild Indigo, Pea family (Leguminosae), Native
Closeup Wild Indigo

Toward the end of July, wild indigo (Baptisia tinctoria) puts out its modest blossoms in wooded areas of the Reservoir. The flowers are yellow and pea-like. The plant's leaves turn black when they are dried.

Like beans, peas, and clovers, wild indigo is a legume. This group of plants is known for capturing nitrogen--an important plant nutrient and a key ingredient in fertilizer--from the air and incorporating it into a chemical form that plants can use. Legumes do this in partnership with certain kinds of bacteria (Rhizobium), which they house and nourish in root nodules. Together, the plant and the bacteria make a chemical that protects these bacteria from oxygen, which harms them. The bacteria, in turn, make nitrogen available to the plant. This process also enriches the soil with nitrogen.

Fringed Loosestrife, Primrose family (Primulaceae), Native

Fringed Loosestrife
Fringed loosestrife (Lysimachia ciliata) blooms on sunny wet shores of the Reservoir, starting in mid-July. The hairy stalks of the leaves are the "fringe."

Fringed loosestrife is the sturdiest of three yellow loosestrifes that bloom at the Reservoir in July. They are not members of the loosestrife family (Lythraceae), which includes purple loosestrife (Lythrum salicaria). Instead, they are all members of the primrose family (Primulaceae).

The name loosestrife comes from an old belief that certain plants could calm agitated animals (loosen their strife), such as the oxen used for farm work.

Cardinal Flower, Bluebell family (Campanulaceae), Lobelia subfamily (Lobelioideae), Native
Swallowtail on Cardinal Flower
Swallowtail on Cardinal Flower

Brilliant red cardinal flowers (Lobelia cardinalis) generally make their first appearance in late July. They bloom in sunny spots at the water's edge of the Reservoir and along the stream that feeds it. By August they are usually out in full force, sometimes in sizable colonies. Their abundance has varied considerably over the past several years. Recently, in years when summer water levels have been low at the Reservoir, they have flourished in damp, sunny sections of the depleted stream bed leading into the Reservoir.

Cardinal flower may have been named either for the red of our native bird, the cardinal, or for the robes of the cardinals of the Roman Catholic church. The scarlet flowers attract hummingbirds as well as butterflies and a variety of other insects. This native North American wildflower spreads both by seed and by shoots, which take two years to grow into mature flowering plants.

Marsh St. Johnswort, St. Johnswort family (Guttiferae or Hypericacaea), Native
closeup Marsh St. Johnswort

Marsh St. Johnswort (Hypericum virginicum or Triadenum virginicum) is a wetlands wildflower, growing in wet, sandy soil near the water. In the long evenings of late July, its small nectar-laden flowers open and then fade by morning. Most St. Johnsworts have yellow flowers, but this one has pink flowers. Like other St. Johnsworts, its leaves are somewhat oblong and are dotted with tiny translucent glands. The plant itself is low and bushy.

Purple Loosestrife, Loosestrife family (Lythraceae), Alien

More Photos Monarch on Purple Loosestrife
Monarch on Purple Loosestrife

In July the first spikes of purple loosestrife (Lythrum salicaria) begin to bloom in sunny, swampy areas, but their flowering peaks in August. Sometimes called spiked loosestrike and known in old England as long purples, the plant came to this continent from Europe. It now flourishes in wetlands here, where it tends to crowd out native wildflowers.

The naturalist Charles Darwin studied purple loosestrife extensively. The plant has three forms, each with male and female flower parts of different sizes. These parts are arranged in ways that prevent inbreeding as bees and other insects move among the flowers, transferring pollen.

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  Copyright © Anne A. Reid, 1999-2002.
  Photographs copyright © Garry K. Kessler, 1999-2002.