Lessons learned at Sabal Palm Sanctuary of South Texas
Are palm trees taken for granted? What do I mean by that? Native plants attract pollinators and wildlife to the yard. Edibles provide food, flavor and nutrition. Hedge shrubs reduce windbreak and add privacy. Flowers are attention hogs with showy hues besides green. Large trees create much-needed shade in our climate. However, what do palm trees do besides impart a sense of the tropics?
A recent to trip to South Padre Island got me pondering the plant. Each year, Texas A&M AgriLife Extension Service horticulture agents from around the state gather for a conference to talk plants, compare programs and learn more about the diverse ecosystems in Texas. One outing sent us to the Sabal Palm Sanctuary, located in the southernmost inhabited area in the state.
History of the Sabal Forest
The Gorgas Science Foundation is a nonprofit organization that educates on conservation of critical natural resources. They partnered with the National Audubon Society, owners of the land, to restore the original Rabb plantation house and accommodate more visitors to the Sabal Palm Sanctuary. GSF president Larry Lof guided us through the history of the palm forest, deforestation and irrigation impacts on water levels (or lack thereof ) of the Rio Grande. Ultimately, what used to be around 60,000 acres is now preserved as the last 29 acres of sabal palm forest in the United States.
Lof points out that walking among these sabal giants is impressive, but the impact is lost from inside the forest. Aerial images best reflect the footprint and impart the importance of such a habitat on wildlife. It is currently critical habitat for migrating and wintering bird species. Prior to deforestation, the trees and fronds were used to make hats, baskets, mats, chair seats, roof thatching and posts.
Also noticeable from aerial views are the scars left from the Rio Grande. With little water coming down the pipeline, this appears to be a meandering river that meanders no more, caught forever in its resacas, the
former bends and channels of the Rio Grande, with little chance of graduating to an oxbow lake.
Sabal mexicana
Sabal palms ( Sabal mexicana) go by so many names it can be confusing: Texas sabal palm, palmetto cabbage and Rio Grande palmetto are just a few. They are tolerant of various soils and can withstand salt, wind and drought. They are recognized as slow growing, coldhardy palms in this area, but prior to ornamental use, these palms did not naturally grow north of the Rio Grande palm forest.
Trees can grow to 50 feet tall with a 2-foot diameter trunk. Trunks exhibit a crosshatch pattern fashioned from the bases of old leaves. Live fan-shaped fronds grow up to 6 feet long and wide, creating a living sphere. The leaflets comprising each frond can tatter and fray into long threads. The effect adds to the plant’s character, softening the sharp, defining points.
As the fronds die, they lay down, hugging the trunk and appearing more like a brown, layered skirt. I used to prefer the manicured look of cleaned up palms until I realized how much resident bats rely on these spaces as a roosting area for cold nights.
A close relative is Florida’s native Sabal palmetto. It’s hard to tell the difference between the two, now that both are grown here, but the Sabal mexicana has a sturdier trunk and larger seeds. It helps to look at photos to notice the difference.
After the freeze, many residents were on high alert to see if there was life to be found in their palms. Some species exhibited new growth before others, but in general, palms take a longer time to recover than other landscape plants. New growth reveals the monocot morphology, as all the growth emerges from the terminal bud at the top of the tree. This is why it is so important not to damage that point.
Current uses
Although, in our region, we will not see forests of sabal palms that can support flocks of migratory birds or apex predators such as the jaguar (yes, they were the apex predator in that forest), using these ornamental trees in our landscape still has benefits. Since they are coldhardy palms that can tolerate our infrequent freezes, they tend to be reliable plants in larger landscapes. This makes them lower maintenance, compared to other cold-sensitive palms.
Even if we do not notice their 7- to 8-feet-long white flower clusters high above our heads, pollinators will. Those flowers are inflorescences that are made of many smaller flowers. This provides a consistent nectar source.
The northern yellow bat is one species that uses dead fronds to roost. They do not migrate but instead take cover within those fronds for protection.
Finally, if you remember, I mentioned that they “impart a sense of the tropics.” That asset cannot be overlooked. Their tropical nature immediately conveys a vacation spot. Who would complain about feeling like they are on vacation just by entering their driveway or backyard? Sign me up.