Gardens of the Cross Timbers: The search for nickernuts

Becky Emerson Carlberg
Contributing writer
Canopy Walk at High Island

Time to get away and Galveston was the place. Salt water and the beach. Just missed the peak migration period of many birds at High Island, Texas. Our birds and insects that spend winter in Central and South America have to cross the hazardous Gulf of Mexico from the Yucatan Peninsula….1,600 miles. High Island is a wood covered haven at the northern edge of the Gulf, unlike many areas along the Texas coastline. The forested land provides food and places of safety for the north-bound travelers. The Houston Audubon Society operates four bird sanctuaries on High Island. Right now, Great White Herons and Roseate Spoonbills, smaller cousins of the flamingo, are nesting in the rookery at the Smith Oaks Bird Sanctuary. I know because it took every bit of courage I had to walk the Katherine G. McGovern Canopy Walkway out to see the birds. Much of the 700 foot long ‘pier’ was 17 feet high. One can be eye to eye with the birds in the trees. The birds could see my terror filled eyes as I struggled with my fear of heights. On the other hand, I was above the mosquitoes.

High Island itself is quite unique, built on top of a salt dome 38 feet high. This may not sound spectacular, but it is the highest point along the Gulf Coast from Mobile, Alabama to the Yucatan Peninsula. Gulf Coast salt domes are referred to as “Islands.” Avery Island in Louisiana is a dome of rock salt 3 miles long and 2.5 miles wide. It’s best known for its Tabasco Sauce. Edmund McIlhenny married Mary Avery, founded the McIlhenny Company and began manufacturing Tabasco Brand Pepper Sauce on Avery Island in 1868.

High Island has arrowheads and sea glass. It is advised to visit High Island with a group, not alone. Know the times for high and low tides and wear thick boots because water moccasins and copperheads are common. Nixed that idea.

The arrowhead makers, the extinct Karankawa, were seasonal nomadic peoples with a common language and culture who lived along the coast from the area of Galveston to Corpus Christi. Few records remain as most info comes from enemies bent on getting rid of the indigenous people.

The Karankawa were voyagers possibly from the Caribbean Islands. Radiocarbon dating of artifacts have been traced back to the 5th millennium BCE. The Karankawa spoke a guttural language, were experts in using dugouts and communicated long-distance by employing intricate smoke signals. To this day no one knows how they trained the smoke to flow the way it did. Their archery skills were considered amazing. The bow, cut from redcedar wood, was as tall as the archer and arrow fletching were wild geese feathers. Their companions were quiet dogs with straight ears of a species similar to coyotes or wolves. The last Karankawa died, or was killed, in the 1860s.

There are shells at Galveston, somewhere. Olive shells, moon shells, angel wings, sand dollars, cockle shells and the Lightning Whelk (Sinistrofulgur perversum) are there. The whelk has a left-handed (sinistral) shell opening on the left side. I found shards. This is the official Texas state shell. No, Oklahoma doesn’t have a state shell. The whelk, a patterned sea tornado-like shell, lives along the coast from North Carolina to Texas. Whelks use a muscular foot to move about, can close off the interior of their shell with a piece of bone-like material, and in 10 to 20 years reach 8 inches in size.

The lightning whelk, a univalve, eats bivalves or sea shells with two halves such as the angel wing and cockle shell. The univalve moon shells (snail-like seashells) and olive shells are predators as well. Sand dollars focus on small crustaceans and microorganisms. It’s a shell eat shell world out there on the beach. I found bits of shells, but nothing intact. The Gulf is rough.


Nickernut sea beans are beach finds. They are of the Caesalpinia genus in the pea family including the showy bird-of-paradise and pride-of-Barbados bushes with their vivid yellow, orange or red flowers and prominent glowing red stamens. The tropical beach nickernuts, which happily grow in zones 8 and 9, come in three species: gray nickernuts (Caesalpinia bonduc), yellow nickernuts (C. ciliata), and brown nickernuts (C. major). The shiny round seeds float in from southeast Mexico and the Caribbean Islands. The parent plants are perfect examples of well-armed defensive organisms. The climbing or sprawling shrubs have sharp, recurved thorns, compound leaves with prickles and produce spiny two-seeded pods reminiscent of sticky cockleburs.

Some of the tough seeds are still viable. The seed coat must be scored (hacksaw blade?) and then the seed soaked in water for at least six hours to a few days before being planted in potting soil. Keep the soil moist and wait one or two weeks to see if a nickernut plant emerges. Or make sea bean necklaces, bracelets and earrings. I hunted endless beaches for nickernuts and arrived at the conclusion they are also a seasonal occurrence. What I did find were lots of water hyacinths (Eichhornia crassipes) washed ashore. This Amazon Basin invasive likes swamps and brackish water. Galveston Bay has a salinity of 10.5 parts per thousand (ppt). The Atlantic Ocean is 33-37 ppt.

Beached Water Hyacinth

Sea glass is another beach curio. One beachcomber found a four-pound chunk of smooth blue sea glass. A real find. Sea glass comes from broken bottles, dishware or even items of shipwrecks tumbled in sea water similar to a rock tumbler polishing rocks. All sharp edges ground off. Sea glass does have value, particularly certain colors. The highly prized red contains gold. Blues are common because of so many blue colored mason jars, glass ware, plates and medicine bottles. Purples less so and turquoise the rarest color. My meager sea glass collection amounted to a few blues and the clear neck of a pop bottle.

My best finds were beach rocks. Sedimentary rocks full of shells called Coquinas. One way or other, I found cool shells.

Becky Emerson Carlberg

Becky Emerson Carlberg, graduate of Oklahoma State (Plant Pathology) is a teacher, artist, writer as well as certified Oklahoma Master Gardener and Master Naturalist. Contact her at