The common trees of Central Texas, and how to tell them apart

Live oak — Quercus fusiformis / virginiana

How to tell: Small, thick, oval leaves, dark green on top and paler beneath, mostly without lobes. Holds them through winter and drops them all at once in early spring, which is the leaf fall people call abnormal every March. Bark is dark and finely furrowed. The form is unmistakable: a wide, low, spreading crown, often wider than the tree is tall.

Where it grows here: Everywhere, on both sides of the escarpment, and the default shade tree of Central Texas.

What goes wrong with it: Oak wilt, and it's the reason for the whole February-to-June pruning rule. Live oaks commonly graft roots with their neighbors and share the fungus underground, so they die in expanding groups rather than one at a time. Structurally, the long horizontal limbs that make the shape are also what fails, usually where two stems meet with bark trapped in the union.

Texas red oak & Shumard oak — Quercus buckleyi / shumardii

How to tell: Larger leaves than a live oak, deeply lobed, and every point carries a fine bristle at the tip — that bristle is the reliable red-oak-group tell. Fully deciduous: bare in winter, and the best red fall colour in this part of the state. Usually a smaller, more upright tree than a live oak.

Where it grows here: The plateau and the Hill Country draws where a bit more moisture collects — Blanco, Johnson City, Dripping Springs, Wimberley, Canyon Lake. Shumard turns up across the whole area as a planted landscape tree.

What goes wrong with it: Oak wilt, and this is the species that makes it everyone's problem rather than just yours. Red oaks are what form the fungal mats that sap beetles carry spores from, so an infected red oak seeds new infection centers across a neighborhood. A red oak that browns out rapidly through early summer and is dead within a season is the textbook picture, and it's worth identifying properly rather than ignoring.

Post oak — Quercus stellata

How to tell: Leaves shaped like a cross or a Maltese cross — the two middle lobes are squared off and much larger than the rest. Thick and slightly rough to the touch. Bark is light grey and blocky. The tree looks gnarled and slow even when it's healthy, with stout, crooked limbs.

Where it grows here: Sandier and gravelly ground: the Lost Pines edge, out toward Bastrop and Lockhart, and pockets across south Austin, Buda and Elgin.

What goes wrong with it: Root disturbance, and nothing else comes close. Post oak will not tolerate grade change, fill over its roots, trenching inside the root zone, or being irrigated like a lawn. The decline shows up one to three years after the construction that caused it, so almost nobody connects the two. If you have healthy post oaks, the correct maintenance is leaving their soil alone.

Cedar elm — Ulmus crassifolia

How to tell: Small leaves — often under two inches — with a sandpaper feel and a toothed edge, arranged alternately on wiry twigs. Frequently has corky wings on younger branches. Flowers and sets seed in late summer and fall, which is unusual and a reliable identifier. Bark is grey-brown with flat, shallow ridges.

Where it grows here: Everywhere, and the toughest common tree in the region. Thrives in Blackland clay where other things struggle.

What goes wrong with it: Co-dominant stems with included bark. Cedar elm loves to fork into two competing leaders at head height, and if the bark gets trapped in that union it never bonds — it's a seam, not a joint, and it's the split that comes apart in a storm. Catching that on a young elm and choosing one leader is fifteen minutes of work that prevents losing half the tree in twenty years.

Pecan — Carya illinoinensis

How to tell: Compound leaves with nine to seventeen leaflets, each one slightly sickle-shaped and toothed. Bark is grey and breaks into narrow interlacing ridges. Big trees have long, heavy, nearly horizontal limbs and a broad open crown. And there are nuts, which settles it.

Where it grows here: Creek bottoms and old orchard ground: east Austin, Seguin, Del Valle, the San Marcos and Guadalupe bottoms. Texas' state tree.

What goes wrong with it: Weight at the ends of long limbs, plus summer branch drop — limbs failing in still, hot weather for reasons that still aren't fully explained. The response is reducing weight at the tips of limbs overhanging things you care about, not thinning the interior. Web worms and alternating heavy and light nut years are both normal and neither is a health problem on a mature tree.

Ashe juniper — Juniperus ashei

How to tell: Scale-like evergreen foliage on rounded twigs, not needles. Shreddy, fibrous bark that peels in long strips. Usually multi-stemmed from the base. Female trees carry small blue-black berries; male trees are what fill the air in December and January.

Where it grows here: The Edwards Plateau: west Austin, Dripping Springs, Driftwood, Wimberley, Bee Cave, Cedar Park. Called cedar by everyone here, including me.

What goes wrong with it: Nothing much kills it, and that's the point — the questions about juniper are about management rather than health. It holds thin soil onto slopes, so clearing mature stems off a hillside starts erosion that won't reverse on rock. It also burns readily, which makes thinning it back from a structure on a greenbelt lot genuinely useful. Take the small stems and the ones crowding better trees; think hard before taking the big ones on a slope.

Bald cypress — Taxodium distichum

How to tell: Soft, feathery, flat sprays of needles that go rusty orange and drop in fall — a deciduous conifer, which surprises people. Fluted, buttressed trunk base, stringy reddish-brown bark, and knees pushing up out of wet ground near the water.

Where it grows here: Directly on spring-fed water: the Blanco at Wimberley, the San Marcos, the Guadalupe, Barton Creek. Some of the oldest trees in Texas are these.

What goes wrong with it: Being planted away from water, mostly. In a normal front yard it survives and sulks, browning early every summer. On the rivers, the real threats are flood scour taking soil off the root plate and construction inside the root zone. A cypress that leans after high water is telling you about its anchorage, not its canopy, and the base is where to look.

Hackberry — Celtis laevigata

How to tell: The easiest one to identify: pale grey bark covered in corky warts and ridges like barnacles. Leaves are asymmetrical at the base, lopsided, with a long tapered tip. Small dark berries the birds strip. Often has clumps of witches' broom in the twigs.

Where it grows here: Everywhere it wasn't planted. It seeds into fence lines, beds and neglected corners faster than anything else in the region.

What goes wrong with it: Weak wood and bad structure. Hackberry grows fast, includes bark in every union, hollows out early and sheds limbs. It's also genuinely useful — it's shade, and the birds live on it — so the honest answer for a mature hackberry out in the yard is to keep it and take the deadwood out. The one over the house or the driveway is the one to be realistic about. Cut stumps resprout endlessly, which is usually the reason to grind one.

Loblolly pine — Pinus taeda

How to tell: Needles in bundles of three, five to nine inches long, with a distinctly twisted look. Cones are stiff and prickly. Bark plates on mature trees are large, flat and reddish. A straight single trunk with the crown carried high.

Where it grows here: The Lost Pines around Bastrop — an isolated island of pine a hundred miles west of where the species otherwise stops, growing on the deep sands there and nowhere else nearby.

What goes wrong with it: Drought, fire and bark beetles, usually in that order and connected. A pine under water stress can't produce the resin flow that pushes beetles out, so drought years are followed by beetle years. Once needles go red on a pine, it's finished — there's no treatment at that point, and the reason to remove it is that it's a standing hazard and a beetle nursery for its neighbors. After the 2011 fire this was most of the tree work in Bastrop for years.