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of the Lower Rio Grande Valley, Texas Landscape Uses and Identificationby the Native Plant Projectthe web version
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Table of Contents
| Introduction | Selecting Shrubs | Planting Shrubs |
| Pruning Shrubs | Plant Comunities | FURTHER READING |
Shrubs
Trecul's Tucca | Mexican Trixis | Skeletonbush | Nopal Prickly Pear | Mexican Caesalpinia | Desert Yaupon | Low Croton | Torrey's Croton | Texas Baby-Bonnets | Texas Kidneywood | Coral Bean | Yellow Sophora | Brush - Holly | Shrubby Blue Sage | Hachinal | Manzanita | Heart-Leafed Hibiscus | Drummond's Turk's Cap | Black Brush | Sierra Madre Torchwood | Chapotillo | Cenizo | Chilipiquin | White Brush | Tamaulipan Fiddlewood | Texas Lantana | Desert Lantana | Oregano
Introduction
An estimated 1,200 native flowering plant species grow in the Lower Rio Grande Valley, Texas, and many of these species are considered shrubs. A shrub differs from a tree in that they are low growing, multi-stemmed woody plants usually not having a single trunk. The Native Plant Project has selected some of the most "ornamental" or "landscape appropriate" shrubs from the numerous native species available to be featured in this handbook. Most are beautiful ornamentals, some are even valuable for wildlife use, but all make excellent landscape plants.
Shrubs native to the Lower Rio Grande Valley have advantages over shrubs brought in from elsewhere. Shrubs from this region have the genetic factors which ensure greater probability for survival. They are preadapted having evolved to tolerate local climatic extremes, local soils, and local diseases and pests. Most of these species are xeric-adapted. This means they require little supplemental water, tolerate drought well, and conserve much of the extra water which exotic shrubs require. Native shrubs have evolved with temperature and rainfall extremes and were 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 shrubs and trees.
Using native shrubs helps conserve rarer species which are vanishing due to habitat clearing. Within the four-county (Cameron, Hidalgo, Starr and Willacy) Lower Rio Grande Valley area over 98% of the natural habitat 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 out a specie all at once and also provides an alternative seed source in the event the last individuals of a species are eradicated from natural habitat.
Some of our native shrubs 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 handbook.) More and different native plants will become available if you demand them. The Native Plant Project will provide sources upon request; the availability of native shrubs changes as nurseries change their available selections due to demand.
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 indigenous to the four-county area of the Lower Rio Grande Valley.
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 human-influenced environment. It encourages the conservation of native species through inclusion in local landscapings. The Native Plant Project works cooperatively with the U.S. 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 meetings 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 Shrubs
The choice of a native shrub, like any other plant, should be dictated by landscaping need and the desired effect. Given the limits of purpose and site, finding a native shrub which will handsomely fulfill every requirement is no problem. Once a choice is made, there remains only a few shrub location and planting tips to be observed.
Obtaining Plants
First, get your shrub 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 shrub is much preferred over a large one, and smaller specimens suffer less transplant shock. With smaller shrub's, chances of survival and rapid growth are very high, they are cheaper, and within a year their size equals those which were initially 2 to 3-times larger.
Site location
Second, most native shrubs do well on most Valley soils. Poorly drained areas should be avoided or mounded for drainage and the shrubs planted on top of the mound. Also many of our native shrubs will grow on a site where a large portion of the soil near the root area is covered by blacktop or paving. Make sure the plant has plenty of growing space and not to plant shrubs too close to houses or pathways.
Planting Shrubs
When to plant
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 can be done but requires much more water, care and maintenance and is equally more stressful on the plant and you than during the cooler late-autumn through early-spring months.
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 from the top 4 to 6 inches, which is richer should be kept separated from the subsoil. Discard the subsoil and replace with the 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 shrub was growing.
Setting the shrub
The depth of the top of the root system should NOT be lower than the top of the hole, it usually kills the shrub when planted too deep. Remove the shrub from the 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 to encourage the roots to grow outward. After setting the shrub in the hole, 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 shrub may be raised and lowered during the filling process to eliminate air pockets thus bringing the roots in closer contact with the soil. When filled tamp the area firmly with your feet.
Watering
The soil around the shrub must be watered thoroughly after the plant 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 the shrub and the amount of rainfall. The soil ball around a newly planted shrub can dry out rapidly and Valley showers cannot be depended upon to supply sufficient moisture during the critical first year of growth. During mid-spring, summer and mid-fall months water all newly planted shrubs for the first 4 to 6 weeks as often as 3 times a week by filling to the top of the soil ring (during the rest of the year a weekly soaking over a 4-week period should be sufficient). Then every two weeks thereafter for the first year, you should provide ample moisture for your shrub to survive and grow. Then let nature do the watering.
Pruning Shrubs
Shrub pruning may be necessary for a variety of reasons. The method and timing can vary depending on the species, age, and condition of the plant. The main reasons for pruning, aside from wanting to create or maintain a rigid, formal appearance, are:
- to remove broken branches which resulted during planting.
- to remove dead branches, or to remove areas infested with insects or disease.
- to correct or improve the shape; for example, a branch may spoil the general balance of the plant, or may grow into other plants or a pathway, or may cross other branches on the same plant and shut out light and air to the center of the plant.
What and how to prune.
Regular pruning is not necessary for most species, or may not be needed at all. To achieve an irregular or informal "natural" looking shrub or hedge which fits into every landscape, except the most formal of designs, the cutting back of individual branches should be done at various levels, removing individual large, medium and small branches, thus creating a soft appearance. Shearing off uniformly the outermost few inches of growth creates a hard, formal outline of a trimmed hedge. REMEMBER when pruning make all cuts at the base of a branch, i.e. at the branching point, leaving only a cut flush with the remaining branch or a stub of less than 1/4 inch (6 mm). Pruning to achieve a "natural" look should be carried out in three stages:
- Removal of large branches is to be made below the center near the base of the shrub. The object being to shorten the overall height of the plant and to open the center for light penetration and air movement. Only one or two such cuts are necessary. The branches removed are from parts of the shrub which are the most crowded and where their loss will be the least noticed. Also they will need to be removed because they are unattractive, damaged or diseased. Care should be given to cutting large branches because their removal will dramatically alter the look of the shrub.
- Removal of medium sized branches is made after the removal of larger ones, to continue the opening of the shrub for air and light penetration and to create uniformity in shrub density; however, care should be exercised to avoid drastic or too much pruning. The overall look of the plant must be taken into account during the pruning progress. Removing branches over the entire shrub one by one and stepping back from the plant to assess the overall effect of balance and density is the best procedure.
- Removal of some of the growing tips is the final pruning stage. This pruning removes only 1 to 3 inches (2 to 8 cm) of growth and is used to continue the opening of the shrub by effecting the overall density. The overall look of the plant will be a soft, feathery appearance resulting from the removal of growing tips here and there over the entire shrub.
Remember the purpose of pruning, except for diseased or damaged branches, is to control growth, and this process should occur gradually throughout the year as opposed to severe pruning once a year. Regular pruning throughout the year results in more air and light penetrating the plant and, for Cenizo especially, produces in leafy growth from the older wood, giving a fuller, healthier, more attractive plant.
When to prune.
The best time for pruning depends upon the shrub, generally after flowering and fruiting is completed. Shrubs that lose their leaves, either in winter or during a drought, this is the best time to prune as they are bare and it allows for the best assessment of the shrub's overall shape and health problems, and for ease in seeing where cuts are to be made. Otherwise, light pruning to control growth throughout the year is acceptable.
Plant Communities of the Lower Rio Grande Valley
Plant communities in the Lower Rio Grande Valley (LRGV) are part of the South Texas (or Rio Grande) Plains which constitute most of the Texas half of the Tamaulipan Biotic Province. The entire Lower Rio Grande Valley lies on the Gulf Costal Plain which extends across the LRGV and Rio Grande to the Sierra Madre Oriental and its outliers. The western part of the LRGV (Falcon Woodland) is also the easternmost part of the shrub-dominated Chihuahuan Desert. Plains and brush land plants reach the LRGV from the north and more eastern plants line the Rio Grande. Several plants have disjunct Trans-Pecos and LRGV distributions. Costal plants reach the LRGV from north and south. Subtropical plants also lend their unique character to the LRGV's subtropical appearance.
Water availability, soil type, and temperatures are the predominant non-human determinants of the LRGV's unusually varied and unique vegetational communities and habitats. Five major vegetational areas include barrier islands, coastal, riparian woodlands, shrublands (chaparrals), and sandplain grassland. These five general areas each consists of many diverse associations and habitats. The LRGV lacks perennial streams and few historic springs survive.
The four-county LRGV is enclosed by the Gulf of Mexico on the east, waterless Sand Plain containing La Sal Viejo and La Sal Del Ray on the north, and an arbitrary (county) line on the west between Flacon Reservoir (in the Chihuahuan Desert) and the Sand Plain. The Bordas Scarp in Starr County is the major component of relief. The Rio Grande (Rio Bravo) separates the Texan and the Tamaulipan portions of the LRGV. The nonpolitical southern boundary is another waterless area between the Rio Grande and the Rio San Fernando. The area of Rio Grande Delta consists of the floodplain broadening eastward, including Cameron, Willacy, and southern Hidalgo Counties and a similar area in Tamaulipas.
The tree-life and water distribution somewhat characterize these five areas. The barrier islands lack trees and the few scattered shrubs never exceed one meter in height. The coastal communities have a few stunted Texas Ebonies or Honey Mesquite trees on holophytic shrub-covered lomas. Freezes permitting, characteristic Black Mangroves shrubs grow near the coastal brackish waters or marshes. The riparian woodlands and palm jungles cover open or dense shrub layers which line the Rio Grande and its resacas. The dry shrublands consists of short trees and shrubs with taller trees around depressions and potholes. The Sand Plain and its bordering habitat lack trees except for isolated groupings surrounded by a sea of grass. Many shrubs in western and northern LRGV can shed leaves during drought stress and regrow them after rain.
Because of the little variation in temperature across the LRGV, our trees and shrubs can be grown under a wide range of conditions with only minor modification of site or care. Riverbank-adapted plants require more water then will other natives. Where necessary, this handbook includes such site modifications in hope of improving success when planting one of the LRGV native shrubs in your landscape.
Everitt, James H., and D. Lynn Drawe. 1993. Trees, Shrubs & Cacti of South Texas. Texas Tech University Press, Lubbock. 213 pp.
Ideker, Joe (ed.). 1984-on. The Sabal, vol. 1- on. [a publication the NPP dedicated to the native plants of the Lower Rio Grande Valley, Texas].
Ideker, Joe. 1994. Checklist of Woody Plants Native to the Lower Rio Grande Valley of Texas, 1989 revision. The Sabal 11 (1): 2-6.
Lonard, Robert I., James H. Everitt, Frank W. Judd, with Norman A. Browne. 1991. Woody Plants of the Lower Rio Grande Valley, Texas. Texas Memorial Museum, University of Texas at Austin., Misc. Publ. No.7. 179 pp.
Miller, George O. 1991. Landscaping with Native Plants of Texas and the Southwest. Voyager Press, Stillwater, MN. 128 pp.
Native Plant Project. 1994. Native Trees of the Lower Rio Grande Valley, Texas. Landscape Uses and Identification. Native Plant Project, Edinburg. 37pp.
Nokes, Jill. 1986. How to Grow Native Plants of Texas and the Southwest. Gulf Publishing, Houston. 404 pp.
Vines, Robert A. 1960. Trees, Shrubs, and Woody Vines of the Southwest. University of Texas Press, Austin. 1104 pp.
Wasowski, Sally 1995. Native Gardens for Dry Climates. Crown Pub. Group. 210 E. 50th, New York, NY 10022.
Wasowski, Sally, and Andy Wasowski. 1994. Gardening with Native Plants of the South. Taylor, Pub. Co. Dallas, TX. 208pp.
Wasowski, Sally, and Julie Ryan. 1985. Landscaping with Native Plants: Landscaping Region by Region. Texas Monthly Press, Austin.
Wasowski, Sally with Andy Wasowski. 1988, 1991. Native Texas Plants: Landscaping Region by Region. Texas Monthly Press, Austin. 406 pp.
Produced by The Native Plant Project
Printed by Gateway Printing, Edinburg, TX
Printed on recycled paper using environmentally friendly ink
THE NATIVE PLANT
PROJECT
of the Lower Rio Grande Valley
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, Texas. The Native Plant Project periodically updates and issues lists of endangered species of the Lower Rio Grande Valley and checklists of its woody plants.
Native Plant Project
P. O. Box 2742
San Juan, TX 78589
Acknowledgment
The Native Plant Project wishes to thank it's Board members for
producing this handbook.
Shrubs