Ask Mr. Smarty Plants

Here are some wildflowers that you could find blooming in September and October in both regions, from the Piney Woods and southwest towards San Antonio:

Amphiachyris dracunculoides (broomweed)

Berlandiera pumila (soft greeneyes)

Chamaecrista fasciculata var. fasciculata (partridge pea)

Conoclinium coelestinum (blue mistflower)

Commelina erecta (dayflower)

Coreopsis tinctoria var. tinctoria (golden tickseed)

Eupatorium serotinum (lateflowering boneset)

Liatris elegans (gay feather or blazing star)

Nothoscordum bivalve (crowpoison)

Oenothera laciniata (cutleaf evening-primrose)

Phytolacca americana (American pokeweed) may still be blooming, but should have purple berries from the Piney Woods almost all the way to San Antonio.

Ruellia humilis (fringeleaf wild petunia) from the Piney Woods almost all the way to San Antonio

Salvia azurea (azure blue sage)

Solidago altissima (late goldenrod)

Verbesina virginica (frost weed)

Flowers blooming that begin on the western edge of the Piney Woods and extend through the San Antonio area are:

Calylophus berlandieri (Berlandier's sundrops)

Euphorbia bicolor (snow on the prairie)

Glandularia bipinnatifida var. bipinnatifida (prairie verbena)

Helianthus annuus (common sunflower)

Helianthus maximiliani (Maximilian sunflower)

Liatris mucronata (cusp blazing star)

Ratibida columnifera (Mexican hat)

Ruellia nudiflora (violet wild petunia)

Thelesperma filifolium var. filifolium (stiff greenthread)

Common grasses that occur in both regions are:

Andropogon gerardii (big bluestem)

Andropogon glomeratus (bushy bluestem) in damp places.

Bothriochloa laguroides ssp. torreyana (silver bluestem)

Bouteloua curtipendula (sideoats grama)

Bouteloua hirsuta (hairy grama)

Chasmanthium latifolium (Indian woodoats)

Elymus virginicus (Virginia wildrye)

Eragrostis intermedia (plains lovegrass)

Panicum virgatum (switchgrass)

Schizachyrium scoparium (little bluestem)

Tripsacum dactyloides (eastern gamagrass)

In the Piney Woods the most spectacular fall colors occur on the Liquidambar styraciflua (sweetgum), Quercus michauxii (swamp chestnut oak), Nyssa sylvatica (blackgum), Rhus copallinum (winged sumac), Sassafras albidum (sassafras) and Carya alba (mockernut hickory). Major evergreens in the area are: Pinus palustris (longleaf pine), Pinus taeda (loblolly pine) and Pinus echinata (shortleaf pine). Juniperus virginiana (eastern redcedar) also occurs there as well as all the way to the San Antonio region.

Trees with colorful fall foliage that span the two areas are: Quercus shumardii (Shumard's oak), Rhus lanceolata (prairie sumac), Ulmus americana (American elm, and Ulmus crassifolia (cedar elm).

In Central Texas near San Antonio it is the red oaks that are most spectacular, Quercus buckleyi (Texas or Spanish oak) and the Shumard oak. Major evergreens in this region are Juniperus ashei (Ashe's juniper), Juniperus virginiana (eastern redcedar) (which also occurs in the Piney Woods), Quercus virginiana (live oak), and Quercus fusiformis (plateau oak).

The timing and intensity of the fall foliage colors in both regions varies depending on the environmental conditions and species of tree. The day length, the temperature and the available moisture can influence both the timing and the intensity. Colder temperatures and low moisture tend to cause earlier fall colors. Warmer temperatures and abundant moisture delay the color display. In East and Central Texas fall leaf color may begin appearing as early as mid-October or as late as mid-November. The full peak of color may not occur until late December. Drought conditions may result in early leaf fall for some species (e.g., the elms) and in less intense colors. Some of the oaks may not lose their brown leaves until late winter (February) or until the new leaves begin to emerge in the spring.

If you are interested in the mechanism for the fall leaf color changes, The Weather Channel has a nice discussion.