Late Summer Wildflowers

August 28, 2014 Ashland Nature Center. Hockessin, Delaware

5:29 p.m. sunny with no clouds in the sky

The wildflowers course for the naturalist certification series was arranged a bit differently from our other lectures and field trips. Rather than learn a bit about the environments where we would likely find flowers and information on the plants themselves, both the lecture and the time in the field were focused on identification. We learned how to use a handy little book, Newcomb’s Guide to Wildflowers, which has a system based on examining the structure of a plant’s flower and leaves to narrow down what species it must be. Joe taught the class and recommended the Stokes Guide to Enjoying Wildflowers for further information about the flowers identified with Newcomb’s, and that was my first source for the information below.

We covered very little ground on our wildflowers field experience, because very little distance was needed to find more than a dozen species. Split into groups of two or three, we chose flowers in the meadows near Barley Mill Road and used Newcomb’s to identify them, noting their families, scientific and common names, and whether they were native flowers. In most cases, we also managed to flag down Joe for confirmation before moving on to the next plant.

I learned earlier this year that goldenrod is not a wildflower but rather a collection of them, the genus Solidago, which grow in many different habitats. In fact, along with asters, goldenrods have a shortcut built into Newcomb’s because you know from the beginning that it’s a goldenrod - the trick is figuring out which one. My group started with a couple goldenrods, curious about what distinguishes different species.

Composite Family

In all members of the composite family, what is often regarded as the “flower” of the plant is actually a collection of many small flowers on a single flowerhead. Some of these small flowers can be confused for petals if not closely inspected.

Goldenrods

Stokes starts its discussion of goldenrods by noting that they are well-known for the showy yellow they cover fields in and mistakenly blamed for people’s allergies. Goldenrods are pollinated by insects and therefore the pollen is sticky and unlikely to become airborne. Stokes suggests just 1 to 2 percent of the airborne pollen in August is from Goldenrod, although the flower is conspicuously blooming in summer. Also blooming, but much less noticeable, is ragweed, which relies on the wind for pollination and is the cause of most people’s hayfever.

The name of the goldenrods’ genus, Solidago, means “to make whole,” which Stokes speculates is related to the medicinal properties of European species, some of which help heal wounds. Most goldenrods, however, are native to North America; there are more than 100 species, and they will hybridize, making a definitive listing of species difficult.

In bloom, goldenrods produce a lot of nectar and pollen, attracting many insects that feed on one or the other, or both, as in the case of honeybees and bumblebees. Syrphid flies, which mimic bees, feed on the nectar as well, and soldier and long-horned beetles eat the pollen. Goldenrods support predators of these primary consumers as well, such as crab spiders and ambush bugs, which take their prey as their name implies.

Goldenrod beetles eat the plant’s leaves, and tree-hoppers feed on its sap. Ants have been seen to protect tree-hoppers from predators, and even the goldenrod plant itself from the goldenrod beetles. Young tree-hoppers exude excess sap they have taken from the plant, and the ants, in turn, are able to feed on this excess.

Other insects make their homes in goldenrods, which form four kinds of galls depending on the insect that caused it: ball (fly), elliptical (moth), bunch (midge) and blister (midge). In all cases, the gall is the result of larvae feeding on the plant; after the gall forms, the larvae live inside it. In some cases, insects called inquilines move into the gall as well, and in other cases - as we’ve seen on previous trips with this class - the original larvae are eaten by parasitic insects.

Rough-stemmed Goldenrod (Solidago rugosa)

This species of goldenrod has a hairy, or rough, stem; toothed leaves; and curved, one-sided clusters of flowers, yellow, of course, like all but a few species of goldenrod. It is common in fields and thickets, growing to heights from 1 to 7 feet.

Lance-leaved Goldenrod (Solidago graminifolia)

This species looks quite a bit different from Rough-stemmed goldenrod. To start, the flower cluster is flat at the top of the plant, instead of the curved clusters that grow at different heights towards the top of the rough-stemmed. The leaves are narrower and entire, rather than toothed. It is also a common species and likes moist to dry open soil. It grows to between 2 and 4 feet high.

Canada Goldenrod (Solidago canadensis)

More like the rough-stemmed than the lance-leaved, Canada goldenrod has the curved, one-sided flower clusters and toothed leaves, although they are narrower than the rough-stemmed. The stem is quite different, however; on the Canada goldenrod, the stem is smooth near the base of the plant and downy above - it feels soft. It reaches heights ranging from 1 to 5 feet and likes fields and roadsides.

This is the only specific species of goldenrod Stokes discusses in any depth, noting it is very common in fields. The Canada goldenrod usually does not flower the first year, just growing a leafy stem before dying back to overwinter as roots. The second year, Canada goldenrod flowers and “begins its vigorous vegetative growth” during which four or five rhizomes grow from the base of the stem. The rhizomes each send up stems and rhizomes of their own, and the repeated process can lead to colonies of goldenrod often eight feet in diameter, so dense other plants rarely intermix. Stokes notes that colonies 30 feet in diameter, estimated to be 100 years old,  have been found in prairie ecosystems.

Other Composites

Jerusalem Artichoke (Helianthus tuberosus)

Stokes refers to the Jerusalem artichoke as the “most well-known perennial sunflower.” Like Canada goldenrod, Jerusalem artichoke has extensive rhizomes underground that can send up new stalks, but the rhizomes are also noteworthy because they grow tubers, which are edible, though not eaten as often in North America as they once were. The tubers are about an inch in diameter and a few inches long. They can be eaten raw or boiled and peeled like potatoes, though they taste like artichoke hearts, according to Stokes. They should be harvested after the first frost but stay fresh in the ground until spring. Also like the goldenrods, Jerusalem artichoke and other perennial sunflowers overwinter as rhizomes, growing new stalks each spring.

There are more than 60 species of sunflowers, all native to the Americas, and most coming from the Midwest. The image most people have of a sunflower is actually a plant that does not grow in the wild, the result of human cultivation stretching back to the Plains Indians, who planted sunflowers among their maize crops. The wild plant from which those sunflowers originate is the common sunflower, an annual, “which has smaller flowerheads, smaller seeds, and thin, branched stalks.”

New York Ironweed (Vernonia noveborasensis)

This wildflower has lance-shaped and very finely toothed leaves. It produces an eye-catching purple flower, especially attention-grabbing in a field of goldenrod. It is distinguished from tall ironweed by the bracts that cover the base of the flower head. On the New York Ironweed, these appear needle-like and individual, where the Tall ironweed has bracts that are more whole and blunt.

We actually identified two different individual plants of New York Ironweed, though, because they appeared slightly different, including the bracts, a good reminder of the variability in any species. But it was good practice to go through the process again and discover there was not an alternative but similar species, but rather evidence of variation.

Rose Family

Small-flowered Agrimony (Agrimonia parviflora)

These plants have flowers in dense spikes or racemes, stalks of flowers extending upward from the plant, and fruit that clings to clothing. Their leaves are compound, with five to 15 leaflets each, depending on the species. Small-flower agrimony is in the upper range, which is a good identifying feature for this species as opposed to the others. It also has a hairy stem.

Fabaceae family

Crown vetch (Coronilla varia) - non-native

Although in the same family (pea/bean), Crown vetch is not actually a vetch. It looks very similar to true vetches, but it lacks the tendrils at the tips of its leaves that flowers in the Vicia genus. Flowers of crown vetch grow in a cluster reminiscent of clover from the axil, the place where the leaf joins the stem. It has a dozen or two leaflets on rambling leaf stems (I can’t remember the proper name for that part of the plant).

Vervain family

Blue Vervain (Verbena hastata)

The genus name of the vervains, Verbena, means sacred plant and came from a European species that had various medicinal and magical uses. It was brought to North America by colonists as a result and has since escaped into the wild, but that vervain, Verbena officianalis, was not the one we found on our trip.

We found a common native species, Blue vervain, which likes wet soils and competes well with meadow grasses thanks to a mat of roots it sends out from a woody stem belowground that gets larger every year. The perennial plant overwinters as small red buds just below the surface of the ground and send up new shoots each spring at the base of its old stalks. The shoots grow to two to six feet tall, quite tall by mid-summer, when they start to bloom with tightly clustered blue flowers.

Vervain blooms for up to three months, ending around September. The flowers open in succession, moving up the stalk. The nectar from the flowers - five petals gathered in a tube - is a food source for bees and butterflies, and the seeds produced by vervain are eaten by sparrows. Given the long time spent blooming, it is not a surprise that Blue vervain has fruit and flower on its stalks simultaneously, and it takes its time distributing its seeds as well. The small, oblong, red-brown seeds are released throughout the winter from the stalk, which remains standing after it has died. Although many seeds are produced and released over a lengthy period of time, they are not typically dispersed very far, perhaps a short distance by wind.

Figwort family

Carpenter’s Square (Scrophularia marilandica)

Also known as Maryland Figwort, this was a flower on which we had to be corrected. We had identified it as Hare figwort before Joe set us straight, and they are quite similar. Newcomb’s says the two are distinguished by how coarse the toothing of the leaves is - Carpenter’s Square is not as coarsely toothed as Hare figwort. Like the lobelias, discussed next, figworts have a two-lobed upper lip to the flower and a three-lobed lower lip, although on figworts the central lobe on the lower lip is bent down, so the flower does not give the same impression as the lobelia. They have undeveloped stamens under the top lip; on Carpenter’s Square this is brown or purple.

Lobelia Family

Indian Tobacco (Lobelia inflata)

These white or light-blue flowers struck me for their diminutive size, growing on a raceme above a stem with toothed leaves. Once you examined the flowers themselves, though, the typical lobelia structure is apparent, with two-lobed lip above and a three-lobed lip below. In addition to the small flowers, the overall plant  is also unassuming in size, growing up to a height of three feet.

Nightshade Family

Horse Nettle (Solanum carolinense)

The shape of these flowers was the most striking characteristic of Horse nettle for me - each flower really is star-shaped, with a cone of stamens in the center. As you would guess from its common name, the plant itself is prickly.

Mint Family

Water Horehound (Lycopus americanus)

Although in the mint family, Water horehound is a kind of bugleweed and does not have a strong smell, even when the leaves are crushed. Its leaves are distinctive - opposite and changing from deeply lobed to toothed as they move up the stem. It only grows to two feet tall and is common in moist areas.

Flowers we passed by because we knew them and did not identify with Newcomb’s:

Jewelweed (Impatiens capensis and I. pallida)

Ashland features robust growth of both jewelweeds common to the East, Spotted Jewelweed (Impatiens capensis) and Pale Jewelweed (Impatiens pallida). While several features distinguish the two plants, the most obvious during late summer is the color of their flowers; the spotted jewelweed has spotted orange flowers while the pale jewelweed’s flowers are yellow.

Jewelweed’s flowers are interesting for reasons other than identification, however. Jewelweed produces two kinds of flowers, open (chasmogamous) and closed (cliestogamous). The open flowers rely on insect pollinators, while the closed ones self-pollinate. Self-pollination requires less energy, producing less pollen, smaller anthers and sepals and no petals or nectaries. But they lack open flowers’ advantage of cross-pollination, which can produce offspring better suited to the environment. Jewelweed tends to produce more open flowers in the summer when there is more sunlight and therefore more energy availalbe and produces more closed flowers later in the year, right up until the plants are killed by frost. (The moisture and shade for each individual plant also affects the ratio.)

The open flowers go through two stages. First is a male stage in which it has a whitish pollen at the top of the flower’s opening, where it will rub onto the back of insects crawling down to the nectar at the flower’s base. This is followed by the female stage, which accepts the pollen and forms jewelweed’s fruit.

Jewelweed’s fruit is fascinating as well because of the way it distributes the seeds. Once ripe, the fruit springs open at even a light touch, flinging seeds up to four feet away. Because jewelweed is an annual, these seeds form the entire potential for next year’s plants, although in moist areas, this does not seem to hold jewelweed back at all.

Cardinal Flower (Lobelia cardinalis)

This is a distinctive plant, with its tall stalks supporting long, tubular red flowers. These bloom for up to three months, from about July to September, as the plant’s flower stalk continues to grows at the tip and produce new flowers.  Like jewelweed, each flower has a male stage, then a female stage; a tube just above the flower first produces pollen, then extends a Y-shape to collect pollen. Hummingbirds and day-time moths pollinate the plant as they reach into the long-tubed flower below.

The fruits develop at the base of the flower and eventually release hundreds of tiny orange-brown seeds that are scattered by the wind. Cardinal flowers overwinter as seeds and rosettes, which grow just outside the original base in late summer and fall, the same time the seeds are maturing. Come spring, each rosette will send up from its center a new flower stalk. Where the cardinal flower is cultivated, the rosettes can be separated from the plant in the spring and replanted to establish new ones and spread the flower out.

Joe Pye Weed (Eupatorium spp.)

As it turns out, it is possible we should have taken the time with the guide to identify the Joe-Pye Weed we saw, as I discovered when reading Stokes that there are four individual species of the plant. They vary slightly in appearance, and the leaves of Sweet Joe-Pye Weed smell like vanilla when crushed, but in most significant ways they are alike.

Joe-Pye Weed is a perennial that overwinters as a dense mat of shallow roots, sending up straight stalks in the spring that don’t branch out until they reach where the flowers will be produced in late summer. The leaves of Joe-Pye Weed are neither opposite nor alternate and instead grow in a whorled pattern. Not only do the leaves grow around the stalk at each group, the groups themselves are staggered and allow the plant to avoid shading out its own leaves. The number of leaves per whorl varies among individual plants, even in the same species, ranging from three to seven.

The plant’s flowers are its most distinctive feature and, coupled at times with its considerable height, make it hard to miss and easy to identify. The flowers are clusters of purple composite flowers, though they lack the ray flowers of other composites like daisies. The flowers are popular with butterflies and last several weeks. The seeds are distrbuted by the wind, on “fluffy parachutes” as Stokes describes it, during the fall and winter, sprouting the next spring. Joe-pye weeds prefer moist areas, and the Stokes guide explains they are often seen at the side of roads because the run-off creates those moist conidtions favorable to the plant.