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Tree Handbook
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Welcome to the Online Version of the Tree Handbook

Montezuma Baldcypress
Texas Sabal Palm
Black Willow
Coyote Willow
Live Oak
Granjeno
Sugar Hackberry
Cedar Elm
Texas Ebony
Tenaza
Texas Huisache
Wright's Catclaw
Guajillo
Tepeguaje
Honey Mesquite
Retama
Texas Paloverde
Mescal Bean
Guayacan
Jopoy
Colima
Western Soapberry
Brasil
Coma Del Sur
Chapote
Rio Grande Ash
Anacahuita
Anacua

Introduction:

 

An estimated 1,200 native flowering plant species grow in the lower Rio Grande Valley, Texas, and of these at least 28 species reach tree size. The Native Plant Project has selected 28 of these trees to be featured in this publication. Some are beautiful ornamentals, some prove invaluable for wildlife use, and others make excellent shade trees.

The lower Rio Grande Valley has a relatively small number of tree species. Many would not be considered trees in areas with abundant rainfall. Thus, all types of trees can be considered together in one brochure. The non-exclusive types include ornamentals, shade trees, and a few primarily useful in restoring converted natural habitats. Most provide cover, shelter, nest sites, and food to urban birds and wildlife as they do in their natural habitats. 

Trees native to the lower Rio Grande Valley have advantages over trees (even of the same species) brought in from elsewhere. Trees of local origin have the genetic factors which ensure greater probability for survival since they are preadapted having evolved to tolerate local climatic extremes, local soils, and local diseases and pests. Except for the few species which usually grow with their roots nearly in the water of the Rio Grande or resacas, most local native trees are xeric-adapted. This means they require little supplemental water, tolerate droughts well, and conserve much of the extra water which exotic trees require. Many fit well into xeriscapes. Native trees have evolved with the temperature and rainfall extremes and remained relatively unharmed during the Christmas freezes of 1983 and 1989 which devastated the non-native plantings. A little extra water though may greatly lengthen the flowering period of xeric-adapted trees and shrubs.

Using native trees helps conserve rarer tree species which are vanishing as habitat clearing and conversion continues apace. Over 98% of the natural habitat of the four-county area has been converted or cleared for urban, agricultural, or industrial use. Establishing rare species in landscapings spreads out the individuals so one catastrophe cannot take them all at once and also provides a reserve seed source in the event the last individuals of a species are eradicated from
natural habitat. As few as a single individual plant of some lower Rio Grande Valley species survive in natural habitat.

Some of our native trees are readily available from most nurseries in the lower Rio Grande Valley. Rarer ones can be found only at the few nurseries specializing in lower Rio Grande Valley natives. (See list inserted in booklet.) More natives will become more readily available if you demand them. The Native Plant Project will provide sources on request; availability of native trees changes as nurseries change their available selections as demand changes. 

Founded in 1982, the Native Plant Project's purpose is to protect and conserve the native plants (including Endangered), habitats, and environment of the lower Rio Grande Valley and promote the use of local native plants in local landscapes. One method it uses is disseminating information about native plants and habitats. Its definition of a native plant is one native to the four-county lower Rio Grande Valley (Cameron, Hidalgo, Starr, and Willacy Counties). 

The Native Plant Project encourages the protection of native plants through conserving and restoring native habitats in refuges, natural areas in parks, wildlife management areas, and private sanctuaries. It works to protect both natural habitat and the human-influenced environment. It encourages the conservation of native species through inclusion in local landscapings. The Native Plant Project works cooperatively with the Fish and Wildlife Service, Texas Natural Heritage Program, Texas Parks and Wildlife Department, and many private organizations toward protecting Endangered Species, including those local natives imperiled but yet unlisted. 

The Native Plant Project currently holds general meeting eight times per year. Members are advised of meetings, field trips, and other activities through The Sabal, which conveys information on the native plants, habitats, and the environment of the lower Rio Grande Valley. The Native Plant Project periodically updates and issues lists of endangered species of the lower Rio Grande Valley and checklists of its woody plants.

 

Selecting Trees

 

The choice of a native tree, like any other plant, should be dictated by landscaping needs and the desired effect. Given the limits of purpose and site, finding a native tree which will handsomely fulfill every requirement is no problem. Once a choice is made there remains only a few tree location and planting tips to be observed. 

First, get your tree from a reputable, reliable nurseryman. DO NOT transplant from the wild...not only is this rarely successful, it diminishes our threatened natural plant and animal habitats. A healthy, vigorous looking small tree is much preferred over a large one, and smaller specimens suffer less transplanting shock. Smaller trees, their chances of survival and rapid growth are very high, do not need staking or artificial supports. 

Second, all the native trees do well on most Valley soils. The possible exception is semi-arid species like mesquite, huisache and paloverde which can not take poor drainage. Also, few of our native trees will grow on a site where a large portion of the root area is covered by blacktop or paving. Make sure the tree has plenty of growing space and be sure not to plant trees too close to houses, power lines or other structures.

 

Planting Trees

 

Preparing the Site

A hole should be dug sufficiently deep and wide enough to hold the full root system. In very poor soils it should be wider and deeper. As the hole is dug, the soil usually from the top 4 to 6 inches, which is richer should be kept separated from the subsoil. Discard the subsoil and replace with fresh top soil or improve the subsoil by mixing at least 1:1 subsoil to moist peat moss or excess media from the pot in which the tree was growing.

 

Setting the Tree

The depth of the top of the root system should NOT be lower than the top of the hole, it usually kills the tree when planted too deep. Remove tree from container, if roots are so numerous they are encircling the soil ball, cut the root ball to a depth of 2 inches with a sharp knife vertically on opposite sides of the ball to encourage roots to grow outward. If planting a tree with burlap covering the root ball, place tree in hole with root ball level with top of hole, loosen the burlap from the trunk, fold back uncovering the top of the soil ball. After setting the tree, soil should be added gradually working the first lot in firmly at the base of the root ball, then filling the hole with more soil, the tree may be raised and lowered during the filling process to eliminate air pockets bringing the roots in close contact with the soil. When filled, tamp the entire area firmly with feet.

 

Supporting

Newly planted trees may need some artificial support to prevent excessive swaying from the strong winds in the Lower Rio Grande Valley which will disturb and break up the root system. For trees up to 20 feet, 1 or 2 strong stakes, 6 to 8 feet, should be driven 2 feet into the ground about 6 inches from the trunk. Wide cloth tape wound around the tree and then nailed to the stake will support the tree. Commercial tree braces are available.

 

Pruning

Nursery grown trees should not need pruning. However, during planting branches may be broken. These should be cut off with sharp pruning shears flush with the branch base or to a growing bud.

 

Watering

The soil around the tree must be watered thoroughly after the tree is set in place. A ring of soil at the perimeter of the filled hole, 4 inches high, should be made for holding water. The frequency of watering depends on the type of soil, the size of tree and the amount of rainfall. The soil ball around a newly planted tree can dry out rapidly and Valley showers cannot be depended upon to supply sufficient moisture. During midspring, summer and midfall months water all newly planted trees for the first 4 to 6 weeks as often as 3 times a week by filling to the top of the soil watering ring (during the rest of the year, weekly soaking for 4 weeks should be sufficient). Then every two weeks thereafter for the first year, should provide ample moisture for your tree to survive. Then let nature do the watering.

 

Maintenance

Selection of a proper planting site reduces the need for maintenance. Remember to allow for growth; the mature tree requires more space than the youngster being planted. Do not plant large trees under utility wires or eaves or close enough to buckle pavement as the tree grows. The best times to plant in the lower Rio Grande Valley are late autumn (to allow for root establishment and dormancy before any freeze) and mid-February after danger of freezing has passed. Planting during the hotter months here requires much care and maintenance. 

Young trees require heavy watering to establish adequate root systems, then water can be reduced to little more than nature provides (about 25 inches per year in Cameron County, 20 inches per year in Hidalgo County, and 15 inches per year in Starr County). Too much overwatering kills xeric-adapted trees which cannot tolerate standing in water-logged soils for more than a few days at a time. A little extra water may lengthen flowering periods greatly. Water primarily at the drip line (under the outer ring of leaves where rainwater naturally drips off the tree). Watering at the base promotes weak root systems that allow trees to blow over more easily and rots the base of the trees.

Pruning should be avoided except to remove dead, dying, or diseased branches. Remember many of our xeric-adapted trees may drop their leaves when they receive too little water, a drought adaptation. Try watering before removing them. Removing too many lower branches reduces their value as cover for birds escaping urban pets, as well as making them unsightly. Excessive pruning and topping promotes access for disease organism and pest insects.

Mulching reduces weed growth, soil moisture loss, high summer soil temperatures, and soil compaction. Pull the large grasses before they become well-rooted and produce seed. Use of weedeaters and lawnmowers can kill young trees by girdling the trunks, thus preventing passage of water and food. Keep these machines a safe distance away. Such mechanical damage also in validates the nursery's warranty.

 

Plant Communities of the Lower Rio Grande Valley

 

Water, soil and temperature are the predominant determinants of the Valley's vegetational communities or biomes which are unusually varied and unique. Four major vegetational areas are the barrier islands, the coastal prairies and marshes, the river flood plains and the brush-grasslands. These areas are enclosed by the Gulf of Mexico on the east, the Rio Grande on the south, the Bordas Scarp (limestone or caliche ridge) on the west and less distinctively, the South Texas plains in the north.

The tree-life in these four areas is particularly characteristic. On the barrier islands, except for some scrubby mesquites, huisache and retamas, there are few if any trees. Moving westward through the coastal prairie and marshes, thesesame species along with ash, hackberry, and willow become more abundant and larger. Along the river and resaca banks and in the brushlands areas the number and variety of tree species increases manyfold. Nature has allowed considerable overlap in these four areas where a particular tree species might be found growing.

While humans have certainly contributed to this overlap, we benefit from it because it means our native trees can be grown under a wide range of conditions with only minor modifications of site or care. Where necessary this booklet includes such modifications in hopes of insuring success and satisfaction when you plant one of our native trees in your landscape.

 
Montezuma Baldcypress ] Texas Sabal Palm ] Black Willow ] Coyote Willow ] Live Oak ] Granjeno ] Sugar Hackberry ] Cedar Elm ] Texas Ebony ] Tenaza ] Texas Huisache ] Wright's Catclaw ] Guajillo ] Tepeguaje ] Honey Mesquite ] Retama ] Texas Paloverde ] Mescal Bean ] Guayacan ] Jopoy ] Colima ] Western Soapberry ] Brasil ] Coma Del Sur ] Chapote ] Rio Grande Ash ] Anacahuita ] Anacua ]
 
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 This site designed and maintained by Bert Wessling. Comments Welcomed.