Gardens of the Cross Timbers: Finally, a field trip

Becky Emerson Carlberg
Contributing writer

Last Saturday found me at Oxley Nature Center in Tulsa.  Oklahoma Native Plant Society hosted a field trip to investigate grasses and plants.  Several came wearing masks, hats and sunglasses while carrying cameras and cell phones ready for pictures.  As a matter of fact, three of the photos accompanying this article were taken by tween Molly Malone, talented photographer and mushroom enthusiast!

It took our group no time to locate the tall Indiangrass, Johnsongrass and Purpletop tridens along the mowed path in a large open field.  Partially hidden but poking heads eight inches high from the ground were dainty Lady’s Tresses (Spiranthes sp). Orchid populations are considered vulnerable and fragile in many of the central US states into Canada. Orchids growing in a prairie! The delicate spikes of spiraling white flowers were in stark contrast to the rougher textured tall grasses and wildflowers.  

As we walked toward the woods, White Crownbeard (Verbesina virginica) was in bloom everywhere.  Ever see it?  A tall plant with clusters of white flowers on winged stems.  The wings look like thin green leaves that flare out from the stem. The late season drought tolerant nectar plant is eagerly sought by Monarchs and other butterflies.  If the season is kind, frostweed can grow six feet tall. Perhaps you’ve heard of frostweed or iceweed?  This is the plant.  When the first frost hits, the stems burst as sap, supplemented with water from the roots, oozes out. It freezes into curls and feathery ice sculptures.  All this beauty at the base of the plant.  Monica Maekle from San Antonio says the iceweed ribbons look like nature’s meringues.

Duckweed Pond

Oxley Nature Center lies within 2,800 acres that compose Mohawk Park.  The city park had been a floodplain and was mainly wetlands before modifications were made. In the 804 acres of the Nature Center live 700 species of plants, 38 mammals (including a few flying squirrels) and 263 species of birds.  

I will testify to at least one species of bird at Oxley…the red-headed woodpecker.  Four young woodpeckers were having an argument or loud discussion in the trees above our heads at the time we were admiring the gangly Eastern Gamagrass, a distant relative of corn.  This indigenous perennial can live 50 years.  The red heads ignored us and continued with their racket.  Unlike other woodpeckers, the red head catches insects in air like flycatchers, and likes to eat and store acorns.  Red-headed woodpecker populations have severely declined the last 50 years, so to watch and hear these birds was a special treat.  

Wingstem and honey bee

Sprouting high in the grasses was another plant with green leaf-like flanges (wings) on the stems.  Wingstem (Verbesina alternifolia) is another tall fall bloomer.  The plant looks like ironweed until it produces large yellow flowers with two to ten slender but long deep yellow petals around a center of spikey little florets.  The small flowers resemble plump greenish yellow needles stuck in a pin cushion.  The central plant stem is winged with green leaf-like flanges. The Xerces Society rates this plant as having special value for honey and bumble bees, wasps and butterflies.  

As we neared a new path, what I thought was ragweed on steroids turned out to be Sumpweed (Iva annua), a close relative also in the sunflower family. The plants have concentrated in the south-central states to Nebraska.   Sumpweed. What a name.  Weeds in stagnant water.  Sumpweed, or the more dignified name Annual Marshelder, lives in…wait for it…… marshes!  With pollen that rivals that of ragweed, annual marshelder may also cause hay fever, flair up asthma and give rise to contact dermatitis.

The Large-seed Marshelder (Iva annua var. macrocarpa) was domesticated 4,000 years ago by Native Americans for its large edible oily seeds high in protein, minerals and B vitamins (37% protein and 45% oil).  Similar to wheat, it had to be grown in large crops for a decent harvest.  Marshelder seeds were often mixed with sunflower and squash seeds for food.  At the same time, giant ragweed was also cultivated for seeds and oil.  During the late Prehistoric (AD 900 to 1600), the Large-seed Marshelder went extinct, possibly because of the introduction of maize (corn).  Ragweed too disappeared from people’s diets, but this plant managed to survive quite nicely.  FYO: Ragweed seeds taste like wheat bran or the flavor of the raisin bran box. Common ragweed is quite adept at removing lead from soil.  

Mushroom and Asters

The Nature Center is traversed by over ten miles of paths with trail names such as Bird Creek, Blue Heron, Coyote, Whitetail, Woodpecker, Mushroom, Red Fox, Blackbird, Salamander, Yellow Warbler and Green Dragon.  Somewhere along Bob’s Trail near the Teaching Center were a few bright green fern fronds in the shade under some trees.  

The Cut-leaf Grape Fern (Botrychium/Sceptridium dissectum) began life as one stalk with the typical but sterile compound fern leaf, but now, in autumn, a separate stalk had shot up from the base of the first fern stalk.  This fertile stem had produced little grape-like sporangia containing future fern spores soon to be released. The fern fronds will soon turn a fall bronze color.  Growing in the shadows but yet so very photosynthetic green, the cut-leaf fern derives most of its nourishment from mycorrhizal fungi living in the soil around its roots. This fern can live over five decades, but is a devil to cultivate.  Love them where they grow!

Lady's Tresses

On the paths we met families who cheerily gave other trail walkers wide berth before stopping to look and listen at nature in action.   Scout troops and patrols were out for an adventure and some merit badge work. We wound our way back toward the Oxley-Yetter Interpretive Building past duckweed covered ponds and duckweed covered turtles, stands of rushes, white and red mushrooms rising up through the leaves, green and tan shelf fungi attached to sides of tree stumps and orange fungal blobs oozing out of wood.  The ramp led to the porch overlooking a small pond with bobbing turtles, fish and a white egret standing proudly at the other side.  Pipevines grew over the fence.  Monarchs and Pipevine swallowtails, defined by their striking blue hindwings, fluttered in the wild flowers below. Honey bees buzzed around a white hive where we entered the building.  Inside were glass walls and rooms with animal and plant exhibits, a classroom, work areas and wildlife viewing area.

The weather had been very cooperative that day Although it felt I was far from the maddening world, jets often flew overhead, reminding me civilization was, in fact, quite close.  I half-way expected to see a golf ball come flying from the Mohawk Golf Course that bordered the park on the northwest side.  

It was great to do some “forest bathing”, socializing and botanizing.  I came away with pictures, happy memories and one chigger bite.

Oxley egret

Becky Emerson Carlberg, graduate of Oklahoma State (Plant Pathology) is a teacher, artist, writer as well as certified Oklahoma Master Gardener and Master Naturalist. Contact her at