Know Your Natives – Yellow wingstem

Yellow wingstem or yellow ironweed (Verbesina alternifolia) of the aster (Asteraceae ) family is found in the U.S. from Texas to Nebraska to Wisconsin and thence east and south.  In Arkansas, the species is found throughout much of the state, though is less frequent in the Mississippi Alluvial and West Gulf Coastal Plains.  The genus name perhaps alludes to a Verbena-like appearance, although the exact etymology is unknown, while the specific epithet refers to the plant’s mostly alternate leaves (note, though, that some plants may have a few or primarily opposite leaves).  The common name “yellow wingstem” may be confused with other species in the genus (see end of article for a short discussion on the other species).

Yellow wingstem is an herbaceous, erect, clump-forming but sometimes rhizhomatous perennial that reaches heights of 4 to 8 feet.  It occurs in fertile, sandy to rocky mesic soils of floodplains, woodlands, thickets, ditches and prairies. Its scabrous (rough-hairy) stems may be winged, partially winged or without wings. Stems are light to medium green with purplish coloration at leaf nodes or along entire stems. Stems are branched in the inflorescence only.  Upon flowering, stems can become less erect.

Lanceolate to narrowly ovate leaves, about 10 inches long and 2½ inches across, taper from mid-leaf to both an acute to acuminate point and a narrowly winged petiole.  Lower leaves may be opposite while upper leaves and those in flowering branches are usually alternate.  Leaf margins are smooth below mid-leaf and slightly serrated above mid-leaf.  The upper surface is dull medium-green and scabrous while the lower surface is light green and less rough with white hairs along major veins.  When stems are winged, narrow bands of leaf blade tissue extend down the stem (decurrent) to the leaf directly below.  If stems are not winged, leaf blade tissue stops at the stem (sessile leaf) or a petiole may be present.

Yellow wingstem - Verbesina alternifoliaPhoto 1:  This yellow wingstem plant, which does not have wings, has a scabrous stem with purple nodes and upper stem.  Also on this plant, lower leaves are opposite.

Yellow wingstem - Verbesina alternifoliaPhoto 2:  This winged plant is nearly hairless.  Purple coloration between green wings extends along leaf rib.

In late summer to early fall, stems have a loose panicle of composite flowers on branches near the top of the plant.  A few to a half-dozen or so flower heads on scabrous peduncles occur on each branch.  Flower heads are 1 to 2 inches across, each with up to 10 reflexed, yellow ray florets (ligules) and several to 30 fertile disk florets.  Rays, rather haphazardly arranged, have a notch at the end.  Disk florets consist of five-lobed, tubular extended yellow corollas that have sharply reduced green bases.  Disk florets, with five stamens with white filaments and purple anthers, are tightly compressed so that they appear to be one.  Stamens initially totally enclose the pistil so that, when stamens emerge from the corolla, the pistil is not evident.  As a flower further matures, stamens wilt back into the corolla tube, the pistil emerges from the corolla, and the stigma becomes bifurcated (divided).  Corolla tubes of matured flowers, with enclosed wilted stamens, quickly drop off the inferior ovary to expose developing green fruits.  Each flower head is surrounded by a calyx-like involucre composed of several rows of loosely arranged, elongated, acuminate phyllaries (bracts).  Flower heads, excluding the rays, have a spherical shape.

Yellow wingstem - Verbesina alternifoliaPhoto 3:  Long, widely spreading branches of the inflorescence and extended disk florets on spherical flower heads are characteristic of the plant.

Yellow wingstem - Verbesina alternifoliaPhoto 4:  Flower head on left displays haphazard ray floret  arrangement, tubular disk florets, compressed stamens and forked stigmas.  Flower head on right (upside down) shows phyllaries of involucre and developing one-seeded fruit (red arrow) just after corolla tubes dropped off.

A single indehiscent (not splitting), one-seeded fruit (achene) is produced by each disk floret.  Achenes have a flattened ovate shape with tapered ends, side wings and two short awns (bristles) at the tip.  Mature achenes can be easily removed by brushing against the awns.  Loosened achenes may be dispersed by strong wind or carried by birds and other animals.

Yellow wingstem - Verbesina alternifoliaPhoto 5:  Spherical nature of flower head remains as achenes mature.  Drying achenes easily brushed off head are at upper center of photo.

For a garden, this plant can be easily grown from seed.  Considering the plant’s height and its tendency to sway over with flowering, yellow wingstem is probably best suited as a background planting in a larger natural garden.  It does best in moist soils, but can survive some dry periods.  It is a good food source for insects and birds.  It is not favored by deer.

Five species in the genus Verbesina are found in Arkansas, several having common names that may cause confusion.  The three common species are:

  1. Yellow Wingstem or Yellow Ironweed (Verbesina alternifolia) which may or may not have wings and blooms in late summer.
  2. Yellow Crownbeard or Yellow Wingstem (Verbesina helianthoides) which is always winged and blooms in early summer.
  3. Frostweed or White Crownbeard (Verbesina virginica) which is always winged and has white flowers.

Two other species are rarely encountered:

  1. Rayless Crownbeard or Walter’s Crownbeard (Verbesina walteri) is a rare native found on Rich and Black Fork Mountains in Polk County; it resembles Verbesina alternifolia but has white flower heads and lacks ray petals.
  2. Cowpen Daisy or Golden Crownbeard (Verbesina encelioides) is a western species believed to be introduced to Arkansas at a few widely scattered locations; it is a yellow-flowered, short-stature annual with auricles on the leaf bases and lacking stem wings.

Leaves of Verbesina alternifolia and Verbesina helianthoides have a similar appearance.

Yellow wingstem - Verbesina alternifoliaPhoto 6:  Upper and lower leaf surfaces: #1 – Verbesina alternifolia, #2 – Verbesina helianthoides and #3 – Verbesina virginica.

Article and photographs by ANPS member Sid Vogelpohl

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Know Your Natives – Forked Blue-curls

Forked blue-curls (Trichostema dichotomum) of the Mint (Lamiaceae) Family is an herbaceous annual.  It occurs throughout much of the eastern U.S. from Texas to Iowa and Michigan, to Maine and thence eastward and southward.  In Arkansas, it is found throughout much of the state except for the bulk of the Mississippi Alluvial Plain.  The genus name refers to the “hairlike stamens,” and the specific epithet refers to the forked stigma.  The common name also alludes to the forked stigma as well as the blue flowers and bent (curled) stamens.

This plant, germinating in early summer, resembles a garden petunia before axillary branching occurs.  Forked blue-curls, reaching a height of 2 feet or more, have slightly square stems and branches.  Opposite branches and leaves are densely covered with short downy hairs (pubescent) and are slightly sticky.  Plants, other than flowers, are an overall light green color.  Their preferred habitat is well-drained soils of open woods, glades, prairies, and disturbed sites, often on sandy substrates.

Forked Blue Curls - Trichostema dichotomumPhoto 1:  Forked blue-curls plants have uniform color and overall pubescence during the growing season.  Photo taken mid-July.

Leaves are oblong to elliptic, thin and entire (no teeth) with largest leaves being up to 2½ inches long and half as wide.  Blades of leaves are somewhat undulated.  Leaves are widest at lower mid-leaf with a gentle taper to both the tip and petiole.  Pinnate veins of upper (adaxial) side of leaf blades are deeply depressed along mid-rib, creating a slight crease, and slightly depressed elsewhere, while veins on lower (abaxial) side are raised.  Crushed leaves have a lemony odor.

Forked Blue Curls - Trichostema dichotomumPhoto 2:  Leaf blade is entire and slightly creased along mid-rib.

Blooming in mid to late summer, the inflorescence consists of a panicle of cymes, with several flowers at the tips of the branches.  Each cyme, as well as individual flowers, is subtended by a pair of opposite leaves.  A cyme has a single flower growing from between a pair of leaves, then two additional branches grow from that same axil to produce flowers in the same plane.  The size of flowers decreases up the length of the cyme with those at the end not fully formed.  With three to seven flowers in a cyme and hundreds of cymes on a healthy plant, many seeds may be produced.

Forked Blue Curls - Trichostema dichotomumPhoto 3:  Flowering occurs at ends of opposite branches.  Cymes and individual flowers are each subtended by a pair of leaves.

Flowers, opening in early morning, drop petals and stamens by mid-day.  Flowers, on short pedicels, are ½ to ¾ inch long and half as wide, with five petals.  The lower petal is tongue-like and cupped while four upper petals are shorter, broadly rounded, and slightly pointed.  Upper petals are a uniform blue while the lower petal often has white shading with prominent dark spots, or occasionally the lower petal may be the same color as the other petals.  Four stamens, similarly colored as the petals, exsert (extend) dramatically from the corolla in a long curling group.  The pistil, with forked stigma and the same color as the stamens, is hidden within the stamen group.

Forked Blue Curls - Trichostema dichotomumPhoto 4:  Plant with spotted lower petals.  Some plants may not have spots.  Note developing nutlets inside calyx at arrow.

The calyx is composed of five unequally sized lobes, each with a prominent central vein and acuminate (gradually tapering) tip.  When in bud, three larger lobes are positioned over the bud as if to protect it.  As the flower reaches anthesis (fully open), the pedicel has bent noticeably upward so that the flower is positioned skyward for easier access by insects.  The repositioned calyx remains fixed while seeds mature.

Forked Blue Curls - Trichostema dichotomumPhoto 5:  Petals and stamens of flower on right have been removed to expose forked stigma.  Note that calyx is positioned over buds, but is rotated upward by the pedicel when flower is open (see Photo 4 also).

The lobed ovary produces four oblong to rounded nutlets (mericarps).  As soon as floral parts fall off, four green nutlets are clearly exposed.  Mature nutlets, 1/16 to 1/8 inch long and dark brown, have a pocked exterior surface and smooth interior surface.  After flowering is complete, all calyxes are uniformly up-turned and cuplike, having rotated 180 degrees from flower-bud stage.

Forked Blue Curls - Trichostema dichotomumPhoto 6:  Top of a forked blue-curls plant (central stem at red X).   A flower is typically located at the first divide of a branch (red arrow) from which point two sub-branches (yellow arrows) continue with additional flowers along those straight sub-branches.

In a garden setting, forked blue curls would be an interesting plant that is worth considering for an informal setting.  However, plants are late to appear in the growing season and flowers only bloom for a half-day.  Additionally, being an annual, plants can come up in various places in the garden from year to year.  Seedlings may also be prolific in a garden setting and may need thinning each year.

Another species of the genus is found in Arkansas, namely, false pennyroyal or fluxweed (Trichostema brachiatum), but it is restricted primarily to the Interior Highlands.  Overall plant structure of this annual is similar to forked blue-curls, but false pennyroyal has five blue petals of the same shape and size, calyx lobes of the same size, and shorter stamens that are not exserted.

Article and photographs by ANPS member Sid Vogelpohl

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Neat Plant Alert – Downy Gentian

Most people think of brilliantly colored foliage and perhaps fresh shelled local pecans when they think of fall in Arkansas. There’s more going on! Our native wildflowers are also putting on a final show. One of the showiest in the fall is Downy Gentian – Gentiana puberulenta.

Downy Gentian - Gentiana puberulenta
Downy Gentian prefers high quality prairies and glades and is found in scattered counties in the northern third of the state and a few counties in the central part of the state. It has a tolerance for dry soils that is uncommon for most gentians. Downy Gentian is considered rare in Arkansas and is tracked by the Arkansas Natural Heritage Commission.

Downy Gentian - Gentiana puberulenta
The flowers are an intense sky blue with some variation in a local population. Some are deeper blue than others.

Downy Gentian - Gentiana puberulenta
These photos were taken October 11, 2015 at Baker Prairie Natural Area in Boone County

Article and photographs by ANPS member Eric Hunt

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