Unique Trees of North Texas:

Eve’s Necklace

(Styphnolobium affine)

By Susan Henson

This is a unique spring bloomer that has been underutilized in the urban landscape. It is an attractive small tree that can be used under power lines, grows well in shade or full sun, plus blooms pink, fragrant, and wisteria-like flowers in the spring (March, April or May). The seed pods look like the old pop string pearls which help provide year round interest. Could be used as a replacement for Crape Myrtle and creates an impact when grown alone. Eve’s Necklace is a legume and since discovering the roots lack nitrogen fixing bacteria the name was changed from Sophora affinis to the current Styphnolobium affine.

Eve’s Necklace has lustrous green leaves, scaly reddish brown bark, and a rounded crown with yellow hard, dense sap wood. The yellow sap wood is used to make yellow dye. It grows quickly when young and can grow to 6 feet from seed in 3 years. When planted in a sunny location it reaches 15 feet in height quickly and then crown becomes more rounded and the growth slows. When grown in dense shade will become spindly to the point of looking almost vine like reaching for the sun. It is related to the Texas Mountain Laurel (Sophora secundiflora) which is evergreen. Leaves are divided into 6 to 8 pairs of leaflets plus a terminal leaflet on a rachis up to 9 inches long. Leaflets are elliptic to oval averaging an inch long, with a rounded, indented, or pointed tip, with smooth margins, and a rounded tapered base.

This tree thrives in the North Texas area on clay, sand, or limestone but the area should be well drained. The tree is native to Oklahoma, Arkansas, Louisiana, North Central and Central Texas. Once established this tree is extremely drought tolerant and only requires occasional watering. Can grow to 35 feet but have never seen it grow above 20 to 25 feet in height. In the wild it is usually an understory tree but can be found growing in roadsides, prairies, plains, meadows, pastures and open woodlands. Though short lived at 25 years they are easy to grow from seeds or cuttings. The bark is rather thin so particular care needs to be taken to protect young trees from weed trimmers.

The National Champion resides in Real County and is 37 feet tall, 77 inch circumference, a spread of 47 feet and an index rating of 125. There are specimens planted in Fort Worth as street trees on the north side of Park Hill between University and McCart, Turner Park in Grand Prairie, the campus of SAF under the power lines along the coliseum parking lot, San Antonio Botanical Gardens. The specimen in San Antonio Botanic Gardens is named ‘Amy’ and has a dark burgundy flower. The flowers can range from white to burgundy but are usually a lighter pink. This tree should be planted more in the DFW area.

Unique Trees of North Texas:

Bois d’arc

(Maclura pomifera)

By Wendy Pappas

The Bois D’arc (aka: Osage Orange hedge apple, horse apple, “bodark”, monkey ball, bow-wood, yellow-wood and mock orange tree) originally had a native range of river areas in Oklahoma, Texas, Arkansas and in the Blackland Prairies and Post Oak Savannas. The native range overlapped the range of Osage tribe, which gives the tree one of its many names. Almost all of the names relate to the interesting fruit or strong wood. It has been naturalized throughout the United States and Canada.

Osage orange has an adult height of 30-50ft and is often wider than it is tall.  The leaves are 3-5 inches long and 2-3 inches wide, with an oval shape that ends in a slender point.  The leaves are alternately arranged on the thorny branch. They are a dark shiny green on top and paler on bottom, turning yellow in the fall.  The tree has a characteristic arching branch pattern and noticeably colorful bark which aid in identification.

This tree is known for its unusual fruit, which some producers are growing for bioproducts. The fruit looks like a thick orange but is yellow/green on the outside and has more pronounced bumps than an orange.  The fruit produces a milky fluid and woody pulp.  Even though the fruit resembles an orange it is more related to the mulberry family. Although it is not poisonous, the fruit is not usually eaten by animals or humans because of its hard-dry texture. Still, squirrels sometimes eat the seeds as food.  Osage orange is a dioecious species, which means only female trees will produce fruit.

Bois D’arc are hardy to most of the United States and can grow in many different environments but prefer fertile, deep soil.  They can be used for hedge rows as a natural barrier to cattle, the wood is a strong and dense which makes it great for fence posts, tool handles, treenails, and even bows (hence the name given by French explorers).  The yellow-orange color of the wood makes it attractive for many different uses. Osage orange typically lives about 75 years with a moderate growth rate of about 1 foot per year.

In the Cross Timbers, there are several large specimen trees. Vandergriff Park in Arlington has several large Osage orange along Johnson Creek, such as the tree pictured at the top of the page and shown on this map:

Unique Trees of North Texas:

Pecan

(Carya illinoinensis)

By Laura M. Miller

The pecan is an overachieving member of the Juglandaceae (Walnut) family and a large growing, long lived, nut producing tree native to North Texas. A mature tree can be over 100 feet tall and 100 feet wide with a lifespan of over 300 years. The native range of the pecan stretches from Northern Mexico to Northern Illinois where pecans can be found along the banks of the Mississippi river almost all the way to Dubuque, Iowa.

Pecans are one of the easiest deciduous trees to identify in the winter because the shucks that protect the developing nuts usually remain attached to the stems.  The presence of nuts on the ground is also an excellent indication that a pecan tree is nearby.  Pecans produce alternately attached large pinnately compound leaves with 9-17 leaflets.  In spring, they are one of the last trees to leaf out.   Separate male (catkins) and female flowers are produced soon after bud break. The female flowers are borne in clusters on the tips of branches.  The year of a heavy pecan crop, one where nut clusters develop on 50% or more of the branch terminals, are usually followed by a year of light production.  Pecan leaves turn yellow before falling from the tree around the time of our first frost.  Falling leaves are soon followed by falling nuts. Because they smell and look a lot alike, pecan trees can be confused with Black Walnut, Juglans nigra, or any of the nine species of hickory that are native to Texas.  They are sometimes mistaken for other commonly planted species with similar pinnately compound leaves such as Chinese Pistache, Pistacia chinensis, or the native Western Soapberry, Sapindus saponaria, both producers of inedible berries rather than delicious nuts.

Long before being named the State Tree of Texas in 1919, the pecan played an important role in Texas history.  When Cabeza de Vaca was shipwrecked in Texas in 1528, he documented the pecan as an important dietary staple of the Native Americans he encountered.  Pecans were gathered in the fall and eaten through the winter months when food was scarce. Today residents of North Texas can gather or purchase pecans and keep them in the freezer for those times when food is scarce.  A one ounce serving of pecans provides 3g dietary fiber (11% Daily Value), 3g plant protein, mostly monounsaturated fat and significant quantities of Thiamin, Beta carotene, Magnesium, Manganese, Copper, and Zinc.

Native pecan trees are found primarily in deep alluvial soils near rivers and streams and are especially abundant along the major rivers of North Texas, the Red, Trinity, and Brazos.  Pecans can be planted at any site in North Texas that can accommodate a large shade tree.

Native pecan trees produce nuts that vary in size, shell to nut ratio, and flavor, Since the 1880s, which is not very long for a cultivated crop, horticulturist have been selecting the best native trees for propagation.  In the 1930s, the United States Department of Agriculture began a pecan breeding program that continues to this day in Brownwood and College Station.  Many of the most highly recommended cultivars for the Cross Timbers have come from this program including Caddo, Oconee, Pawnee, Kanza, Nacono, Sioux and Wichita.  Desirable, the leading cultivar in the state that produces the most pecans whose name must not be mentioned, is also an excellent choice.  The sentimental favorite is probably Burkett, a native selection widely distributed by J.H. Burkett North Central Texas in the 20s and 30s. The trees of cultivars made famous by Arlington nurseryman O.S.Gray in the 40s, 50s, 60s, and 70s such as GraKing and GraTex still grow in many Arlington landscapes.

Even though no other shade tree offers the key ingredient to delicious pies, pralines, cookies, and German Chocolate Cake frosting, pecans do have some negative qualities as landscape trees.  They are messy dropping not just nuts in the fall but also leaves and petioles that don’t rake up easily.  In the spring those male flowers can be almost as much trouble to clean up as the leaves in the fall.  Couple this with a tendency to drop branches due to shade, heavy nut crops and possibly just because they want to, and you have a tree that is exceptionally well suited to someone who very much enjoys picking up sticks (and leaves, and petioles, and catkins).  Like most plants that produce something good to eat, pecan trees will attract lots of birds, especially crows, squirrels, racoons, and foraging neighbors.  Insects are also fond of pecans, and you can expect Pecan Nut Casebearers, Hickory Shuckworms, and Fall webworms. Pecan scab is a serious fungal disease problem east of I-35 and can be problematic here if environmental conditions are conducive to disease development.  Fortunately, there are many excellent cultivars that are scab resistant.  Pecans grown on high pH calcareous soils benefit from foliar zinc sprays.

The National Champion pecan (pictured above) is in Parker County near Weatherford. In the Palo Pinto town of Oran, the Goodnight-Loving Pecan sheltered the 1866 partnership of cattlemen Charles Goodnight and Oliver Loving. In Fort Worth, the Hollow Pecan of the Fort Worth Botanic Garden (RIP 2014) no longer shelters small children hiding from their parents, but there are many old large native pecan trees there and across University Avenue in Trinity Park.