End of Summer Flowers – August 2021

This summer has been notable for a late spring, then heat, drought, dashes of rain, and smoke. Flowers burst forth starting in June, sped along with the warmth, but then began to crisp early in many locations. Reports include tall forb and alpine flowers averaging three weeks early. 

Flowers still bloom along streams and shady canyons, and road sides are sporting late summer yellows in abundance. Fruits are ripening fast. Here are some of the most obvious flowers at lower elevations, which means they should still be going strong farther up the trail. Butterflies are active on these remaining nectar sources: fritillarys, coppers, blues, tortoiseshells, and parnassia, to name the more recognizable groups.

Showy Goldeneye (Vigueria/Heliomeris multiflora) is abundant along roads, in meadows, and up hillsides ranging from Jackson Hole to Yellowstone National Park. The cheerful yellow heads wave atop slender 2-3’ stems with mostly opposite leaves. Sometimes the rounded ray flowers are visibly lighter toward their ends—under UV light they look like bulls-eyes to pollinators. These “composite” flowers with both ray and disc flowers provide a showy and easy place for pollinators to land and gather pollen and nectar from many tiny flowers. Like going to a big box store.

Pacific Aster (Symphiotrichum ascendens) forms colonies of blue along roadsides and smaller patches in more wooded areas.

They bloom at various heights: mowed, grazed, or just left alone. One way to tell these blue asters from others is to look at the venation of their elongate leaves.  The veins outline elongate areas. 

Curly Gumweed (Grindelia squarrosa ) has colonized along main highways and park roads. Early herbarium records indicate that they have naturalized relatively recently in the county. 

They tolerate drought and winds of roadsides with their tough slightly succulent foliage. Their sap is also thick. Flower heads are sticky and the bracts curl under, hence its common name. It has an interesting fragrance.

Golden Aster (Heterotheca/Chrysopsis villosa) also colonizes park roadsides and collects in dry depressions.  The leaves are clearly hairy, shorter, and the yellow composite flowers abundant. Flowers are now forming heads of individual fruits: each fruit with one seed inside is attached to a fluffy pappus of hairs that helps them disperse into new dry sites. 

Canada Goldenrods (Solidago canadensis var. salebrosa) have been blooming strong over the last few weeks. Goldenrods have a reputation for causing allergies. This is a bum rap. Wind pollinated grasses and ragweeds (Ambrosia spp.), which are found farther east, often bloom at the same time unnoticed. Wind pollen is light and abundant and designed to disperse on the wind, and therefore gets up our nostrils. Flowers with showy petals like goldenrods have evolved to attract insects to carry the pollen from plant to plant—pollen is relatively heavy and not flying about on its own. 

Canada Goldenrod has many slightly toothed, pointed, 2-3” leaves alternating up 2-4’ stems.  Tiny heads contain about 13 ray flowers. Here the many small composite flowers bunched together create a show signaling in pollinators who can perch and wander about for the goods of pollen and nectar. Also, there are many other tiny and large insect crawling in and about the flower heads, some munching, others laying eggs, some just hiding from predators.

For plant nerds: Two other common goldenrods are smaller, smooth all over, with most of their larger leaves bunched near the base. Rocky Mountain Goldenrod (Solidago multiradiata) is distinguished by ciliate hairs long the petiole of the basal leaves and 13 ray flowers per head.

Sticky Goldenrod (Solidago simplex) has smooth petioles and heads with only about 8 ray flowers. Flower heads can be a bit resinous or sticky.

Thickstem AstersEurybia integrifolia – are tough, 2-2.5’ plants seen in a variety of habitats and elevations.

Their flower heads have sticky bracts and stems, and its thick stems tend to zig-zag. Flower heads have deep blue to purple ray flowers surrounding the yellow to rusty disc flowers. Lower leaves are much larger than those along the upper stems.

Fireweeds (Epilobium/Chamerion angustifolium) were also notably early this year and some didn’t bloom at all. Those still blooming tend to be at high elevations or in moist or shady locations lower down.

If you observe closely, you can see the flowers change flowering stages. First the anthers (above) produce male pollen while female part located in the center is still undeveloped. Then the anthers wither and the female stigma matures (below) ready to receive pollen from another flower. This progression from male to female avoids flowers self-pollinating. Flowers at the bottom of the inflorescence bloom first.

Many plants are already going to fruit and seed. Their seeds, dispersed on the wind, remain viable for only a few weeks.

In high meadows where fireweed can be abundant, hummingbirds are important pollinators. They load up on nectar before migrating south. Hummingbirds lap, don’t suck, nectar. They have little bristles at the tips of their tongues and rapidly dart their tongues back and forth into their long beaks while hovering. Truly a feat.

Rufous Hummingbirds Turning Up in Unusual Places | Audubon
Rufous Hummingbird – National Audubon Society

Rabbitbrushes are flourishing right now, with more to come. They are particularly important for supplying nectar at the end of the flowering season: look for myriad butterflies, bees, and other winged invertebrates working them over.

We have a 4 common varieties of rabbitbrushes in Teton County. These shrubs typically range from 1-3 (4)’, grow in relatively dry, sunny conditions along roadsides and hillsides, often on disturbed soils. They stand out at this time of year. Once in one genus, they are now split into two. All have linear leaves and bunches of flower heads with only yellow disc flowers, giving them a similar appearance. The varieties can be difficult to tell apart!

Rubber Rabbitbrush (Ericameria nauseosus) has straight narrow leaves and tomentose (felt-like hairy) stems. They smell when broken and when fresh twigs can exude a white sap – hence “rubber” rabbitbrush and nauseosus in the name. 

For the botany nerd:

var. oreophilus (above) has very narrow 1-nerved leaves, greenish tomentose stems, and smooth involucral bracts.  2.5-5’ tall.

var. nauseosus has white tomentose stems, narrow grayish green leaves, and tomentose (hairy) involucral bracts. 1-2’ tall.

Compared to Rubber Rabbitbrush, Yellow Rabbitbrush (Chrysothamnus viscidiflorus) typically has twisted, often wider, leaves, often with stiff hairs on leaf edges (ciliate). Also they are somewhat sticky e.g. viscid, as in the name.

var. lanceolatus has hairy upper stems and often hairy leaves which are mostly 2-6 mm wide. Involucral bracts are hairy. More common and low growing at 6-18” high than var. viscidiflorus (not shown.)

See the next posting for fruits found at this time of year. https://wordpress.com/post/tetonplants.org/4696

Frances Clark, Program Coordinator, Teton Plants, Wilson, WY

tetonplans@gmail.com

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