Antelope horns dots the roadsides

Photo Credit: Claire Sorenson

Lately, no matter which direction I head I have seen antelope horns milkweed dotting the roadsides of central Texas.

The leaves of milkweeds are the primary food source for the Monarch caterpillar and the flowers provide a nectar source for the adult butterfly that has a high glucose content.

Antelope horns is not finicky about water. It has a large tap root that develops quickly which allows it to flower even during years like this one when rainfall has been pretty scarce. It prefers to grow in well drained soil in full sun.

The easiest method for planting is to sow the seeds outdoors in September to November. This gives the seeds the exposure to the moisture and cold temperatures that it prefers, and once the temperature is warm enough in the spring, the seeds will germinate.

Beginning in June, aggressively trim back one plant at a time, to provide fresh foliage for butterfly larvae all summer long. Another method includes a careful cold stratification in the refrigerator before spring planting.

Photo Credit: Claire Sorenson

This milkweed gets its name from the seed pods that look similar to the horns of an antelope. Its scientific name Asclepias asperula is derived from Askelpios the Greek word for the god of medicine and asperula the Greek word for rough. In Greek mythology the Greek god Askelpios brought Orion back to life. The Greeks believed that Askelpios could use his powers to bring any of the dead back to life. The constellation Askelpios is also called the serpent holder.

As the scientific name seems to suggest antelope horns is credited with many medicinal properties. Cardiac glycosides which are present in the sap of the milkweed are allied to digitalins used in treating some heart disease. Native Americans made a tea from milkweeds as a tonic to strengthen the heart and the Navahos also used it as a treatment for the bite from a rabid animal.

The same milky sap that the Native Americans used for medicinal purposes can also be toxic like so many modern medicines today. Not surprisingly, antelope-horn is normally deer resistant and livestock also tend to leave it alone because of the bad taste. Monarch caterpillars capitalize on this toxic trait because once the milkweed is ingested the caterpillars also taste bad.

One other interesting bit of milkweed trivia is that during WWII the silky down attached to the seeds was used for both regular life jackets and aviation life jackets. Milkweed silk is 5 to 6 times more buoyant than cork.

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About the Region

New Braunfels, the location of our Fall 2024 Symposium, straddles both the Edwards Plateau Ecoregion and the Blackland Prairie ecoregion. Interstate 35 divides the city of New Braunfels; its path through the city closely parallels the boundary of these two ecoregions, with the Edwards Plateau on the west side and the Blackland Prairies region to the east. The Edwards Plateau area is also called the Hill Country; however, this general term covers a much larger area extending farther north. Spring-fed creeks are found throughout the region; deep limestone canyons, rivers, and lakes (reservoirs) are common. Ashe juniper is perhaps the most common woody species found throughout the region. Additional woody species include various species of oak, with live oak (Quercus fusiformis) being the most common. Sycamores (Platanus occidentalis) and bald cypress (Taxodium distichum) border waterways. This area is well known for its spring wildflower displays, though they may be viewed in spring, late summer, and fall, as well. According to Texas Parks and Wildlife, average annual rainfall in the Edwards Plateau ranges from 15 to 34 inches.

The Blackland Prairie extends from the Red River south to San Antonio, bordered on the west by the Edwards Plateau and the Cross Timbers, and on the east by the Post Oak Savannah. Annual rainfall averages 30 to 40 inches, with higher averages to the east. This region is dominated by prairie species. The most common grass species include little bluestem (Schizachyrium scoparium) and Indian grass (Sorghastrum nutans) in the uplands and switchgrass (Panicum virgatum) in the riparian areas and drainages. Common herbaceous flowering plants include salvias, penstemons, and silphiums. This area has suffered greatly from overgrazing and agricultural use. Few intact areas remain, though many of the plants can be found along county roadsides throughout the region.

Our four host chapters (New Braunfels, Lindheimer, Guadalupe, and the Hill Country chapters) are located in one or both of the ecoregions above. However, the eastern portion of Guadalupe County also falls within the Post Oak Savanna ecoregion. Annual rainfall averages 35 to 45 inches, with higher averages to the east. A wide variety of hardwood trees are found, including several species of oaks, elms, and in the Bastrop area, loblolly pine (Pinus taeda). Grasses and forbs dominate in the open savannas, with most common grass being little bluestem. Ranching, agriculture, and fire suppression have allowed woody species to encroach on the once-open savannas.

Source: Wildflowers of Texas by Michael Eason