Tough Texas Trees for Houston
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HOUSTON The Garden Club of Houston Hermann Park Conservancy The Houston Parks Board TOUGH Katy Prairie Conservancy Lady Bird Johnson Wildflower Center Memorial Park Conservancy TREES HOUSTON TOUGH TREES summer 2012 Tough Texas Trees for Houston PREFACE In selecting trees for Houston region, it is important Although the change in Houston’s climate over the to remember that we do not know what weather previous three years–moving from a generally wet patterns our region will face in the next few years. climate at approximately 45 inches of annual rainfall It would be unwise to simply select trees from else- to less than 20 inches of annual rainfall–was begin- where that are impervious to drought, as they may ning to be seen, no one anticipated how devastating not tolerate our local soils or the enormous rain that the 2011 summer of record heat and drought would be Houston can be subject to. So, we have emphasized for our trees. here the trees that are both native to our region and A generous gift from The Wortham Foundation, drought tolerant, and thus more likely to survive in Inc., brought the parks and greenspace community all rainfall conditions we may face. Other trees that together to assist the City of Houston. While the City are native to other, usually drier, parts of the state are put tremendous resources into removing dead wood identified separately as they have also done quite well for public safety and fire hazard reasons, we joined the here as long as they are given good drainage. City in saving as many trees as possible and planning Particularly as our climate changes, it is important for the future. to select a diversity of trees that provide food and The immediate response was focused on legacy trees, shelter to the birds, butterflies, and other wildlife those significant because of historic location or size, that enrich our area, so we have also provided infor- and on younger trees with a higher likelihood of sur- mation on which of these trees are particularly useful vival. We treated the root systems of targeted legacy to wildlife. trees for better water and nutrient absorption, and wa- All the experts emphasize how important good plant- tered as much as funding and practical considerations ing techniques and supplemental watering are to allowed before winter dormancy and in the critical establishing trees under dry conditions. So, planting early spring period. Thankfully, spring 2012 turned out tips are included here also. to be average in terms of rainfall. We hope that these lists are helpful to Houstonians Now we look to the future and to replanting. Know- as we together recover from the drought of 2011 and ing what did well under severe drought conditions plant for the future. is important to choosing what trees to replant. This booklet reports the 2011/2012 experience and judg- ment of many of our region’s agencies who manage large public spaces, of expert professional foresters and nurserymen, and of avid gardeners. We are grate- ful to all the experts who helped to create these lists; The Garden Club of Houston all are listed along with other information sources at Hermann Park Conservancy the end of the guide. The Houston Parks Board Katy Prairie Conservancy Lady Bird Johnson Wildflower Center Memorial Park Conservancy LARGE TREES These large native trees were observed to, once established, survive the historic 2011 drought with little or no supplemental watering. HOUSTON LEGEND LARGE SUN TREES PARTIAL SUN SHADE ATTRACTS BUTTERFLIES ATTRACTS BIRDS tough TREES LARGE TREES Bur Oak Quercus macrocarpa Platanus occidentalis American Sycamore Soil: variety of soils, sand, Soil: moist, sandy loam or loam, clay, or caliche silty clay Growth Habit: deciduous; Growth Habit: deciduous; easy and fast-growing; fast-growing and long-lived; resistant to drought, urban broad, dense crown with pollution, fire, insects and very large leaves that are disease; straight trunk bright green on top and with a broad, rounded paler underside; has distinc- crown of stout branches tive, white, exfoliating bark; Flowers/Fruit: largest larger trunk diameter than acorns of all native oaks any other native hardwood Size: 80 feet tall or more Flowers/Fruit: brown balls of small seeds, 1 inch in di- ameter on 3 to 6 inch stems Size: large tree up to 100 feet or more Live Oak Quercus virginiana Platanus mexicana Mexican Sycamore Soil: gravel, sand, loam or Option to American Sycamore clay but does best in neutral The Mexican Sycamore or slightly acid clay loam is a close relative of the Growth Habit: evergreen; American Sycamore and fast-growing and long-lived; is very similar. It averages very resistant to salt spray; 80’ by 50’, fast-growing, full easily transplanted when sun, tolerant of most soils, young; tolerates poor drain- tolerates wet and drought, age and compaction of soil long-lived. It is native to Flower/Fruit: acorns about Mexico but is now being 1 inch long planted in the Houston area. The Mexican Syca- Size: large spreading tree more is preferred to the to about 50 feet tall with a American by many nursery crown of up to 100 feet in people who feel it is more diameter disease tolerant than the American Sycamore, but time will tell whether this is accurate. tough TREES LARGE TREES Pecan Carya illinoinensis Taxodium distichum Bald Cypres Soil: rich, moist, well Option to the Montezuma Cypress drained soils, sand, loam, Bald Cypress is more eas- clay or caliche ily found in the trade and is Growth Habit: deciduous; frequently planted in street fairly rapid growth; excel- medians because of its adapt- lent shaped tree with thick ability to soil and water con- straight trunk, broadly ditions. Bald Cypress knees rounded crown; tolerates can be a problem in poorly poorly drained sites; State drained areas, but the knees Tree of Texas can be controlled by cutting Flowers/Fruit: oblong nut them off with a pruning saw ripening in fall about 1 inch below the soil Size: 70 to 100+ feet tall, surface. The bald cypress is allow plenty of room for deciduous, and the soft, ferny growth leaves turn terra cotta hue in the fall. Montezuma Bald Cypress Taxodium mucronatum Ulmus alata Winged Elm Soil: wide variety of soils, Soil: wide variety of soils, sand, loam, clay sand, loam, clay, caliche Growth Habit: evergreen Growth Habit: deciduous; or semi evergreen; fast- fast-growing shade tree growing and long-lived; with spreading branches needle-leaf, tall straight and rounded top; small trunk, broad crown with serrated dark double ser- spreading branches and rated, green leaves that drooping twigs, few or no turn yellow in the fall knees, tolerates extended Flowers/Fruits: samara flooding and well drained (winged seed pod) Flowers/Fruits: cone bear- Size: 40 – 70 ft. tall ing plant, cones open in February and seeds ripen in October Size: 36 to 80 ft. tall tough TREES LARGE TREES Cedar Elm Ulmus crassifolia Quercus stellata Post Oak Soil: wide variety of soils, Soil: rocky or sandy soils, sand, loam, clay, caliche acid based Growth Habit: deciduous; Growth Habit: deciduous; fast-growing and long- slow-growing and long-lived; lived; large, rounded-crown broad, rounded crown with shade tree with drooping thick, sometimes leaning, branches; dark-green leaves trunk; few pest problem; are small, rough-textured does well soggy soils, ex- and yellow in fall; tolerates tremely drought tolerant alkaline soil but roots are very sensitive Flowers/Fruit: samara to being disturbed (winged seed pod), autumn Flowers/Fruit: small acorns, fruiting different from most ¾” to 1 ¼”, ripen in the fall other elms Size: 50+ ft. tall Size: 30 to 60 ft. tall Eastern Red Cedar Juniperus virginiana var. virginiana Ulmus americana American Elm Soil: wide variety of soils, Soil: well drained, variety sand, loam, clay, caliche of soils, sand, loam, clay, type will tolerate salty soil Growth Habit: fragrant Growth Habit: deciduous; evergreen conifer; cone fast-growing and reason- shape when young but ably long-lived; attractive, more irregular shape when tall shade tree with a sym- older; fluted trunk up to 2 metrical crown of spread- ft. diameter with reddish ing branches that arch and brown, thin bark that peels droop at the tips; thick off in long strips trunk usually divides into Flowers/Fruit: pale blue several large ascending, berries on female plant, erect branches; double ripen September to serrated leaves are 3 to 6 December inches long and very rough on the top surface Size: can get to 70 ft. tall, depends on soil and sight Flowers/Fruit: clusters of conditions single seeds, mature by early summer Size: up to 80 ft. tall tough TREES LARGE TREES ( NATIVE TO DRIER AREAS ) LARGE TREES The following large trees were also observed to survive the 2011 drought with little or no watering. They are native to drier areas south and west of Houston and do well here only if they have good drainage. Green Ash Fraxinus pennsylvanica Quercus muehlenbergii Chinkapin Oak Soil: adapts to a variety Soil: rocky or sandy soil, of soils, sand, loam, clay alkaline Growth Habit: deciduous; Growth Habit: deciduous; upright, spreading habit moderate to fast-growing; with crown shape varying straight trunk with light from irregular to symmet- colored bark and spread- rical rounded; deep green ing crown; attractive summer foliage; relative saw-toothed leaves turn freedom from insects and yellow to bronze color in diseases the fall; seldom troubled Flowers/Fruit: samara by diseases or pests (winged seed pod) on Flowers/Fruit: acorn ½” female tree, large seed up to 1 ¼ ” long crops Size: up to 50 ft. tall Size: 50 to 70 ft. tall tough TREES LARGE TREES HOUSTON Mexican White Oak (Monterrey Oak) (Quercus polymorpha) Soil: wide variety of soils but best in well drained alkaline soils Growth Habit: deciduous to semi-evergreen; fast-growing SMALL - tall at first then spreads its crown; light colored bark; deep green, long, oval leaves 5”-7” creates a lush TREES appearance and has reliable fall color; resistant to oak wilt, diseases and pests; as drought tolerant as the Live Oak once established Flowers/Fruit: medium size acorns Size: 50 ft.