Few plants draw more comment and interest than agaves when they begin to flower. A massive asparagus-like stalk erupts from the center of the rosette and grows inches per day until it branches and flowers, sometimes 20' or more above ground level. Our collection here at the JC Raulston Arboretum has reached the stage where we often have one or more flowering each year. This year we have two plants that will be gracing our Scree Garden with their towering inflorescences.
Agaves have been transient in their family placement shifting around between the Agavaceae, Dracaenaceae, Liliaceae, and most recently the Asparagaceae. Agaves are surprisingly closely related to hostas despite an ocean between their native habitats and vastly different cultural needs. Agaves are often split into two groups, one with a spicate (spike-like) flower stalk and one with a paniculate (branched) flower stalk. Unfortunately, it often takes many years for an agave to flower so mislabeled plants may need some time to be adequately identified.
Agaves are a relatively large genus with about 200–250 species which form rosettes of spirally arranged leaves which serve the purpose of directing water down to the center of the plant and its root-zone. This adaptation is useful in the desert Southwest, Mexico, and through Central America where agaves grow on dry sites, sandy locations, and thin, rocky soils but can make them difficult to grow in high rainfall areas.
The agaves flowering for us this year are Agave scabra and A. ovatifolia both of which have impressive branched panicled flower stalks. Almost all agave are monocarpic meaning they will flower once and then die. Many agave will produce offsets or small plantlets around the base of the main plant before or during the flowering period. This doubles the chance of survival—seed and new plants. Agaves with panicled flower stalks often have thick-textured petals that can stand up to pollination by bats and birds. Other pollinators include various insects and moths.
Agave scabra or rough agave is so named because of the rough (scabrous) texture of the leaves. We received this plant as seed from Peckerwood Garden in Hempstead, Texas, in 2001. It has made a sizeable plant to about 3' tall and nearly twice as wide with numerous offsets. In the wild, it can take almost two decades to flower but in the richer soils and heavy rainfall of the East Coast, it matures much quicker. Our plant is a nice gray-green with strongly recurving leaves with a long vicious terminal point. Backward curved teeth line the edges of the sharkskin textured foliage. The gold flowers are borne in masses atop the 20' tall stalk and serve as a beacon in the landscape. We have found this to be perfectly hardy in our zone 7b garden.
The other agave we have coming into flower this year, A. ovatifolia, known as whale's tongue agave, is one of the best in our garden. It not only tolerates our cold weather but also takes our moisture in stride and is one of the loveliest plants we grow in the genus. The species was originally collected in Mexico by plantsman Lynn Lowery in the 1970s but was not identified and formally named until 2002 when Gregg Starr retraced Lowery's route to rediscover the agave in the wild. The whale tongue agave makes a sizable plant to 3' tall and slightly wider made up of broad, blue-gray leaves with a black terminal spine. Our plants are shy to off-set so we look forward to growing out the seed from the tall, 15' flower stalk. The yellow flowers make a showy display but are typically not as bright as A. scabra. This is perhaps the best of the larger agaves for growing in a sunny spot with average, well-drained garden soil as opposed to the perfect drainage needed for most. It should still be planted high to ensure it does not rot.
Come out to the JCRA to check out these two agaves as they put on an impressive floral display this summer. Arboretum members can look forward to possibly receiving seedlings during one of our many giveaways in the coming year or two as well. With the proper siting, these and other agaves can become texturally important fixtures in the landscape providing drama, substance, and color to the garden.