Longleaf pine upland

The Solo Tract

Often described as the biological crossroads of North America, the Big Thicket Natural Preserve in east Texas offers visitors a fascinating mixture of swamps, forests, grasslands, and sandhills. Since its establishment in 1974, it’s grown to 113,000 acres; its nine units contain nine (or ten) distinct ecosystems, ranging from baygalls and cypress sloughs to pine savannah wetlands and palmetto-hardwood flats.

The Turkey Creek unit alone contains seven ecosystems; more than seventy species of trees and nearly five hundred species of herbaceous plants can be found there. A favorite attraction in the unit, the Pitcher Plant Trail, leads to one of America’s largest displays of carnivorous plants.

Also tucked into the Turkey Creek Unit is a less well-known area called the Solo Tract: a longleaf pine upland purchased from a logging company. Because longleaf pines are resistant to fire, occasional prescribed burns, combined with other forms of clearing, are helping to reestablish the area as a healthy longleaf grassland: the sort of area some describe as ‘a prairie with trees.’

The Solo Tract ~ Longleaf Pines with Little Bluestem

No trails exist in the Solo tract, but wandering is encouraged, and that’s what I intend to do in the coming year. I enjoyed witnessing changes at Walden West from month to month, but was eager for something different. The Big Thicket certainly differs from my usual haunts, so ‘going Solo’ it will be.

The first thing I learned after my January visit was how little I know about pine trees. Both longleaf pines (Pinus palustris) and loblolly pines (Pinus taeda) grow in the Solo tract, and sorting them out can be a challenge. Bark color and texture vary widely, both between and within the two species. Loblolly bark is said to be “divided by shallow fissures into wide, rectangular blocks,” while longleaf bark is described as being “fissured into irregular, somewhat wavy plates;” to my untrained eye, that’s a distinction without much of a difference.

That said, and despite the bark of mature loblolly pines being described as “topped by scaly plates or rounded ridges that are reddish-brown, gray-brown, or gray-black,” my hunch is that this one qualifies as a longleaf.

Certainly Pinus, and probably palustris

The leaves of pine trees — their needles — also help with identification. Longleaf pine needles can attain a length of fourteen inches or more, while those of loblollies typically range from four to nine inches. The needles of both species are bundled together in groups called fascicles; longleaf bundles generally contain three needles, while the loblolly bundles may hold two, three, or four.

Despite similarities between mature longleaf and loblolly pines, juvenile trees are easy to distinguish. After longleaf seedlings sprout, they spend several years remaining close to the ground, looking much like a clump of grass.

During this time they develop a deep taproot, while clustered needles protect their buds from fire. Once they begin growing, they attain height relatively quickly, but branching doesn’t begin until they’re about ten feet tall.

Up, up and away ~ longleaf pine style

Not only do loblolly pines seed and grow in sandy soils where water is close to the surface (‘loblolly’ is an interesting early American term applied to the trees), they begin branching much earlier, and grow more quickly than the longleafs: as much as two feet per year.

A loblolly pine, branching out

Despite a late winter absence of colorful flowers, other hints of color caught my eye as I sauntered down the road shown in the top photo. Stopping to look at a relatively large branch that had fallen into the brush, I realized I’d never seen anything like the bits of purple, yellow, and lavender it contained. Eventually I learned that, despite differences in common terminology, I’d found both male and female cones.

In common with other gymnosperms, pine trees have no flower or fruit. Instead, they produce cones and seeds; the term ‘gymnosperm’ literally means ‘naked seed.’ Unlike angiosperms, or flowering plants, the seeds of pines are not encased within an ovary, and the trees are not pollinated by insects.

Instead, individual trees are monoecious, containing both pollen-bearing male cones and female seed-bearing cones. Pollen produced by male cones (properly termed ‘microsporangiate strobili’) is carried by the wind to fertilize the immature female cones (‘megasporangiate strobili’) which eventually will produce seeds. After maturing, the female cones open and release their seed; eventually, they fall to the ground, becoming the familiar pine cones we collect.

Had a single branch not fallen from one of the tall trees lining the road, who knows how long it would have taken for me to learn these things?

Colorful and intricately patterned male cones

A tiny female cone

Thanks to previous visits to the Solo tract and other Big Thicket sites, not everything seemed so unfamiliar. In time, the purer whites of the Pepperbush and Pipewort; the tall, bright gold of the Miller’s Maid, the purple Liatris, and the delicate shine of the Yellow-eyed Grass will appear. When that happens, I’ll be there to celebrate their new season.