On September 2, 2022, I was visiting the roadside pullout off Hwy 90 about 5.6 miles west of Alpine when I noticed an Agave that had put up a stalk and bloomed. The leaf rosette was dying except for a new, green panicle (the characteristic stalk of the Agave) of about 44 inches in height protruding upward from between the dying and fresh leaves. Knowing that Agaves or Century Plants are typically monocarpic, meaning that they only flower once before dying, I took photographs noting the location and date so I could research the phenomenon. Agaves typically put up stalks and bloom between 8 and 20 years of age.
I showed my photographs to Dr. A. Michael Powell, who is the Director and Curator of the Sul Ross Herbarium and a Distinguished Professor Emeritus of Biology of Sul Ross State University. I told him my story and asked if he was familiar with the occurrence of a new, smaller stalk occurring after the original plant was spent. Dr. Powell related that he had not seen this occurrence before and considered it an anomaly worthy of further study. Dr. Powell also identified the Agave species as Agave americana from my photographs.
Agave is first described by Linnaeus in 1753. The Agave plant has about 27 species in the US, nine in Texas and five in the Trans Pecos. Mexico has a large number of species: over 200 that have been identified, with the greatest diversity of these species found in Oaxaca (43), with other locations like San Luis Potosi (32), Hidalgo (32), Veracruz (32) and Jalisco (38). This high diversity decreases moving south into Central America with numbers in Cuba (15), Colombia (5) and Venezuela (2). Agave americana is a cultivated species that is native to Mexico, South Texas, and Southern Arizona. It was introduced into the Trans Pecos and is distinguished from the five native species as it has larger, lighter-colored green to a moderate gray bluish leaves and a taller inflorescence, which can reach 15 to 24 feet. Agaves are monocots in the Asparagaceae, Agavoideae subfamily classified since 2009. It is a plant that is known to produce a flowering stalk only once, although it can produce offsets or pups from underground rhizomes. But a new stalk after the original stalk is spent is a rarity.
Agaves have many uses, and they have provided humans with food and beverages for at least 9,000 years. Additionally, agaves have been and are still used for fibers (making ropes and clothes), like henequén from a Central American agave. Beverages include pulque, tequila and mescal. Also, their carbohydrates are used for making agave honey. As food, the roasted mature heads and flowers are very sweet and nutritious. Additionally, an unfermented sweet juice, known as aquamiel, can be extracted from the center of an agave, but only when the growing inflorescence is separated. Agaves are also used as ornamental plants all over the world.
The word “agave” comes from the Latin word agave and Greek word aqauē, name of the mother of Pentheus, and from agaous meaning noble. Other sources relate in Greek mythology that “Agave” was the eldest daughter of Cadmus, the King and founder of the city of Thebes, Greece, and the Goddess Harmonia. The term agave was probably adopted by botanists because of the plants’ single, massive inflorescence that is the largest among any plant.
I visited the agave plant 5.6 miles west of Alpine on September 7th, 8th and again on the 14th. The new panicle was developing with flowers normal in size. The new panicle came off the original stalk and was surrounded by green, vibrant leaves in opposition to the original plant’s dying leaves. These undying leaves were the same size as the original leaves as not to be confused with a pup or offset from an underground rhizome. The vibrant leaves were attached to or around the original stalk. On September 8th, with gloves ready to avoid the leaves’ prickles, I determined that the new panicle was connected to the mother stalk by a short (3 to 4 inch) horizonal portion; then the panicle turned vertical. It appeared healthy and developing to open its flowers just like the original mother stalk.
On my September 14th visit, I found the panicle had broken off the original stalk. It was attached six days earlier. The panicle was not wilting yet, suggesting it must have broken off recently. I collected it and took it to Dr. Powell in the Herbarium. My thinking was the panicle got heavy with upcoming flowering and the wind took it down. Dr. Powell was interested in the 48-inch-long panicle and added some flowers from it along with my photographs to the Herbarium collections.
After examining my submissions, Dr. Powell suggested I get in touch with Wendy Hodgson, an agave expert at the Desert Botanic Garden in Phoenix, Arizona. Wendy Hodgson is the Herbarium Curator Emerita and Senior Research Botanist at the Desert Botanic Garden. I emailed her, attaching two pictures showing the Agave and new panicle. She responded that she had seen this phenomenon before and that agaves “want to spread their pollen and get fertilized any way they can.” Ms. Hodgson also pointed out that little flower stalks can develop from the original flower stalk, which was what I was seeing. She also conveyed that she did not know why this happens. The question of what causes the production of additional carbohydrates in a seemingly dying plant to produce a new panicle remains unanswered.
In addition to the Alpine roadside phenomenon, I observed on September 4th, another Agave americana in Marfa, Texas, approximately 24 miles west from Alpine at the intersection of Hwy 90 and South Dean Street. This agave had multiple paniculate flower stalks coming from the dying rosette and spent tall original stalk. The smaller panicles were anywhere from 10 inches to 62 inches in height and were twelve in number! They were in different stages of development, suggesting they arose at different times. Some were small and dead, not having come to flower. The large one (pictured) went to full bloom and produced seeds. This plant also had vibrant, green leaves mixed among the dying leaves of the original rosette, although they were not as large as the dying leaves of the original plant. I took photographs and monitored this plant also. On a later visit, October 14th, I counted sixteen panicles in different stages of development. It was determined that the secondary leaves were still green just like the original plant had been.
Both the agaves at the roadside near Alpine and the one in Marfa are Agave americana, which is an introduced species as noted above. They were surely planted after local construction work was completed at their respective locations.
In examining a 2020 research article (Evolutionary ecology of Agave: distribution patterns, phylogeny, and coevolution (an homage to Howard S. Gentry)), recommended to me by Ms. Hodgson, I found references of this phenomenon with my agaves. Not putting up a second panicle, but where the rosette continues to exist after producing the initial flowering stalk. It seems that in a study in the Valley of Metztitlán in the state of Hidalgo, Mexico, with Agave striata, the rosette did not die after producing an inflorescence. In these agaves, “After the first reproductive event, the axillary buds flower, and the rest of the buds (and the plant) survive.” Interestingly, the A. striata has the highest diversity of floral visitors that can include bats, moths, perching birds, bees and hummingbirds.
I found our local agave anomalies extremely interesting as I had never experienced it in my plant studies. The most thought-provoking questions remain, of course: how and why. The “why” is best addressed with Ms. Hodgson’s quote that they just “want to spread their pollen and get fertilized any way they can”—reproduction being the basis of regeneration of the species. The “how” is still a curious and fascinating question.
I would like to thank Dr. A. Michael Powell of Sul Ross State University and Wendy Hodgson of the Desert Botanic Garden in Arizona for their contributions, interest and support for me in writing this article.
Glossary of subject terms:
Inflorescence-the flowering part of a plant; a flower cluster; the arrangement of the flowers on the flowering axis
Monocarpic-flowering and bearing fruit only once and then dying. The term may be applied to perennials, biennials, or annuals.
Monocots-Plants with a single seed leaf
Panicle(s)-a branched, racemose inflorescence with flowers maturing from the bottom upwards; a flowering stalk
Pedicellatte-with a pedicle
Pedicle-the stalk of a single flower in an inflorescence
Raceme-An unbranched, elongated inflorescence with pedicellate flowers maturing from the bottom upwards.
Racemose-having flowers in racemes
Rhizomes-horizonal, underground stems
Rosette-a dense radiating cluster of leaves usually at or near ground level