CHAPTER IV - Prairies

A little further on is a grassy area which serves as a mini-model of the Blackland Prairie habitat type.  Prairies once covered much of Texas, extending from the western edge of the big Thicket all the way to the Trans-Pecos, and from the Rio Grande all the way to the northern border.  Less than 1% of Texas' original prairie remains.  Most of it has been lost to grazing or crops.

In spring, the dry stalks of last year's grasses are mixed with the current year's new green growth. A prairie fire would return the nutrients locked in leaf litter to the soil.

This is what a native grassland should look like--lots of tall grasses with little brush and very few invader species. Our grasses co-evolved with grazing animals such as deer, antelope, and bison--animals that graze and then move on. The native grasses are the first thing to go after the introduction of grazing cattle that are not moved regularly to fresh pasture. 

Bushy Bluestem, Andropogon glomeratus, has broom-like inflorescences that distinguish it from all of the other bluestems.

This is Little Bluestem, Schizachyrium scoparium. It is one of the most common grasses in the Blackland Prairie regime.

Splitbeard Bluestem, Andropogon ternarius, is also present.

All the bluestems flower in late summer and fall. Their fluffy inflorescences make them easy to recognize.  To a grazer, grasses like the bluestems look like ice cream!

Before the park was established, this prairie area was used to pasture cattle. It was severely overgrazed, with very few native grasses and an abundance of invader or increaser species such as Bitterweed, Croton capitatus, and this Silver-leaf Nightshade (Solanum elaeagnifolium). Now that the area is protected, these weedy species have declined and the native grasses have staged a comeback.

In addition to grasses, a healthy prairie supports many different herbs. Legumes are usually an important part of the flora. False Indigo, Baptisia bracteata, is common in local prairies and pastures. The creamy-yellow panicles of pea-like flowers poke out from underneath the bushy plants. It's a member of the Fabaceae or Bean Family.

Another common legume is Partridge Pea, Chamaecrista fasciculata, which blooms in late summer and early fall. It's one of the few local members of the Caesalpiniaceae.

The Mimosaceae is represented in the park by several species of Schrankia and Mimosa. Look for pink "powderpuffs" beginning in late spring or early summer. They have been given the common name of Sensitive Briar because the leaves fold up when disturbed.

One can also find Milkweeds in open areas. This is Asclepias viridis.

The Blackland Prairie and Post Oak Savannah regions of Texas are believed to be more densely brushy and woody than they were before the advent of European settlement. When wildfires are suppressed, woody plants become more abundant. In addition, fencelines which are neither grazed nor mowed provide shelter for woody species and often become "corridors" of colonization for trees and shrubs. The line of trees shown here follows the path of an old fencerow. It makes a narrow strip of woodland visible from the air.

As we continue on through mixed prairie and stands of trees, we encounter more wildflowers. Many of them are showy monocots. Yellow Star Grass, Hypoxis hirsuta, in the Amaryllidaceae, is a good example.

The Yellow Star Grass looks especially nice with Blue-eyed Grass or Sisyrinchium. The taxonomy of the local species of Sisyrinchium is quite a mess. These plants are members of the Iris family.

Copper Lily, Habranthus texanus. Is another member of the Amaryllidaceae. It pops up, seemingly overnight, after soaking rains in the spring and summer.

Spiderworts (Tradescantia spp.) in blue, purple, and occasionally pink, are abundant along the trail.

Unusual features of Spiderwort flowers are the bow-tie shaped anthers and the furry filaments. The flowers can be of different colors, depending on soil pH and other environmental factors. The cells of the filament hairs mutate easily and the plants have been grown near nuclear plants as a biological radiation detector.

This is not to imply that dicots are absent. Toadflax, Linaria canadensis, can be found every spring, often in great numbers.

Chapter 5 - Upland Woods

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