The Indispensable Tall Thistle

In spring comes the initial burst of wildflowers in Oklahoma. The blooms are timed with the emergence of the first butterflies and other insects as well as the arrival of migratory birds. The mutual sharing of pollen and nectar benefit all wildlife. Although many trees, shrubs and grasses grow and reproduce through the summer season, the pace drops in heat and dry conditions. As autumn approaches, the annuals call it a day and die. Perennials go into winter preparations and hope to see next year. Many Gaura species are biennial. They produce vegetative rosettes one year, stay low and slowly grow through the winter and next spring begin accelerated growth which culminates in some mighty tall, floral displays August and September.

Right now, many Oklahoma plants, triggered by decreasing sunlight and cooler nighttime temps, are preparing for their last hurrah, the autumn flush of flowers and fruits. As in spring, plants are here to feed the birds, butterflies and other fauna. In return the plants are pollinated and set seeds for next year’s generation. The relationships are quite complex but have been in place for thousands of years. People have messed up much of it.

You’d be surprised what plants will do if allowed to reach autumn without being mowed or cut down. They may not look spectacular during the summer, but simply hang on. Maximilian sunflowers appear as leafy stalks until September, then their multiple buds with yellow petals open along the stems. The common sunflowers become vibrant in July and continue through fall. Soft goldenasters (Chrysopsis pilosa), which look like broadleaf weeds, form carpets of small daisy-like yellow flowers where they have been left undisturbed.

Try not to be so human and neat. Countless insects overwinter in plant stems 18 inches and below in height. Larvae live in the leaf litter. Unless there is disease present, why not be a lazy gardener like I am and leave the leaves and debris alone. Edge and trim a border around your selected areas and let nature thrive.

Look at the longer shadows. The color of the sky. Winter is on the way. Sneezeweed (Helenium autumnale) bouquets have sprung up along the roads and in fields. Snow-on-the-Mountain (Euphorbia marginata) decorate the pastures. Along sides of woods are purple ironweeds (Vernonia fasciculata) covered in butterflies and moths. Goldenrods (Solidago species) are beginning their cascades of yellow.

Remember, it is not the goldenrod activating your allergies. Blame the ragweed (Ambrosia artemisia). After all the rains, tall ragweed is attaining magnificent heights, sending the irritating pollen aloft in Oklahoma winds. Ragweed flowers are miniscule unseen upside-down teacups. Don’t trust Google. The site has an abundance of misidentified plants including innocent goldenrods being labeled ragweeds. Gasp.

In natural uncut areas of shade, sun, thickets and roadsides are now blooming native thistles. These super important plants are biennials as are Gaura. Most form rosettes one year, overwinter and flower the next in their 2-year cycle. Bumblebees (often in small groups of twos or threes), gold finches, hummingbirds, butterflies, moths, and a myriad of other organisms use the thistle flower and plant. Late nesters, Goldfinches, build nests and raise young in July and August. They not only line their nests with thistle fibers and eat thistle seeds, they feed their offspring thistle seeds (unlike other birds which offer caterpillars and insects.) Goldfinches rely on the late flowering thistles.

Tall thistle (Cirsium altissimum) is very common in central and eastern Oklahoma. Wavyleaf (Cirsium undulatum) grows statewide, yellowspine (Cirsium ochrocentrum) thrives in western OK, and yellow thistle (Cirsium horridulum) is in the southeast part of the state. Four other species are much less common, but as you see, the native thistles cover the state.

Confusion has arisen concerning the invasive thistles from Europe and Asia. Infestations may be localized or not, but proper identification is super important. Most of these invasives bloom earlier in May and June. They have sharp spines especially along the stem.

Only the tall native thistle blooms in September into October. The flower heads are shaped like compact purplish shaving brushes. The leaves of this member of the aster/sunflower family are shallow lobed and undivided with only very fine spines along the edges. The underside of each leaf has a white bed of velvety down.

Tall means this thistle can reach 6 to 12 feet high! The flowers are usually pink to purple, but on rare occasions white does happen. When touched by fingers, the tall thistle has the softest spines of all the thistles.

“In the sun

the butterfly wings

like a church

window.”

Jack Kerouac