Native Plants Journal 6.1 (2005) 69-71
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Texas Roadside Wildflowers
125 East 11th Street
Austin, TX 78701
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Texas bluebonnets (Lupinus texensis) blooming along Willow Loop Road in Gillespie County, Texas, enhance recreational experiences.
Photo by Tara Luna
roadside seeding, Amblyolepis, Castilleja, Coreopsis, Gaillardia, Glandularia, Lupinus, Oenothera, Phlox, Verbena
USDA NRCS (2004)
Texas is an immense area that is diverse in botanical richness. Encompassing 692 408 km2 (267 339 mi2), dense pine and hardwood forests in the eastern portion of the state slowly give way to blackland prairies and savannah-like oak- grasslands, and southward to semitropical forests of jungle-like swamps, sandy lands, and densely wooded uplands that are home to many state endemics. The arid, southern Great Plains in the northwest drop southward to the semi-tropical lower Rio Grande Valley and the far west region of the Big Bend country is part of the northern reach of the Chihuahuan Desert, considered the most biologically rich desert of North America. In the middle of the state, limestone and granite outcroppings define the Edwards Plateau of the Hill Country, famous for the vast displays of Texas bluebonnets, Indian paintbrush, buttercups and evening primroses, and Drummond phlox.
From early March to the end of October, Texas is literally covered with wildflowers that produce landscapes of brilliant colors. Long undulating waves of constantly changing colors border roadsides, adjacent pastures, grasslands, and forests as one species after another comes into bloom. In many areas, Texas bluebonnet displays stretch as far as the eye can see, creating the illusion of an ocean of deep blue. In late spring and summer, a variegated robe of reds, yellows, and pinks quilt the landscape. [End Page 69] These vast wildflower displays encourage thousands of residents and tourists to drive and bicycle Texas roadways to enjoy the beauty.
In 1932, the Texas Department of Transportation (TxDOT) hired its first landscape architect to maintain, preserve, and encourage wildflowers and other native plants along rights-of-way. Native species that were colonizers in areas after road construction were noted, and development of a management plan to encourage, perpetuate, and protect native wildflower stands was formulated. By 1934, directives were issued to delay all mowing, unless essential for safety, until spring and early summer wildflower seasons were over. This practice has expanded into a full-scale vegetation management system. A combination of selective mowing and herbicide application, wildflower preservation and seeding, and an active public awareness program drives the highway beautification program. The Highway Beautification Act, championed by Lady Bird Johnson during the 1970s, resulted in increased public awareness and added fuel to the existing TxDOT program.
TxDOT strives for a balance in maintenance and management of Texas highways. Maintenance techniques used to encourage wildflower growth include safety, or strip, mowing that allows wildflowers to bloom and native grasses to emerge. Directives to mow around blooming wildflower areas are included in mowing contracts. Mowing does not begin until the mass of spring wildflowers has finished blooming and seeds have matured. During mowing operations, late-blooming species are protected and preserved by leaving them in non-mow areas. Furthermore, it is especially desirable to conserve any rare or uncommon type by leaving these species undisturbed or by restricted management. Fall mowing is used after the first frost to open the canopy, allowing germination of annual species the following spring. Mowing dates also coincide with flowering and seed maturation phenology of perennial species so that they are also allowed to produce seeds.
For statewide use, TxDOT purchases and sows approximately 18144 to 27216 kg (40000 to 60000 lbs) of wildflower seeds (annuals, biennials, and perennials) per year in native and non-native plantings in new construction areas, annual replacement sites, and in locations where they are lacking. In the past, wildflower areas were cut with a sickle mower after the peak blooming season and before seeds dispersed. The "flower hay" was raked up and spread where TxDOT wanted to establish or enhance wildflower populations. Another old...