Some perennials are too easy to grow. Curve leaf yucca, Yucca recurvifolia (or Yucca gloriosa ‘Tristis’), is remarkably resilient. It migrates slowly but surely. If it becomes obtrusive, it is difficult to contain and remove. Removal of foliar rosettes above does nothing to slow the roots below. The roots merely produce new foliage. Of course that can be a distinct advantage for harsh conditions.
The striking foliar form resembles that of other species of Yucca, except that it reliably arches softly downward. Foliage is not as soft as it seems though. Each leaf terminates with a sharp spine. Sharp edges can cause wicked paper cuts. Foliar color is bluish gray. Although, variegated cultivars are increasingly popular. Old plants can develop trunks that slowly grow more than six feet tall.
Tall and elegant spikes of relatively small creamy white flowers stand grandly above the evergreen foliage in late spring or summer. Bloom is best with warm and sunny exposure, and lasts a long time. Viable seed is rare. Propagation by division of some of the many pups is simple though. Popular variegated cultivars exhibit more docile growth with fewer pups, but bloom less abundantly.
After providing remarkably striking foliage for many years, the biggest and boldest agaves bolt with spectacularly tall floral stalks that support horizontal pads of flowers. These stalks can bloom for months, and stand for months after bloom is finished. Then things get ugly. The foliage around each bloom folds back, desiccates and dies. There is no nice way to describe it. Bloom is death.
Plants that bloom only once and then die are ‘monocarpic’. Agaves are not truly monocarpic, since they do not really die completely. They survive by producing pups (offshoots) as their original rosettes of foliage die. Some agaves start to produce pups years prior to bloom, just to be ready. Most terrestrial yuccas (that do not form trunks) go through the same process shortly after bloom.
Pups can be so prolific that they get crowded. Because the larger agaves are so big, they can conquer a significant area with just a few pups. With all their dangerously nasty foliar spines, extra pups are not at all easy to remove. Once removed, pups can be planted elsewhere as new plants, but they will grow up into even more agaves that will eventually bloom and make more pups!
Removal of the carcasses of bloomed yuccas without getting stabbed by the sharply tipped leaves is challenging. Removal of the carcasses of big agaves is hellish! Spines of old foliage never go dull. Pups hiding below the old foliage are just as dangerous. Tall blooms must be cut down like small trees. The debris can not be recycled in green waste, so must be disposed of like trash.
Furcraeas, which are related to agaves and yuccas, produce fewer pups, or may not produce any pups at all. Of course, a bloomed plant without pups will die completely. However, the huge conical blooms (that resemble Christmas trees) produce bulbils, which are tiny new plants that can be plugged back into the garden to grow into new plants! Regardless of all the work, furcraeas, as well as yuccas and agaves (within reason), are worth growing for their dramatic foliage and impressive bloom.
Dracaena palm, Cordyline australis, is not a palm at all. It is more closely related to yuccas. (Incidentally, a few yuccas are also inaccurately known as palms as well, but that is another story.) The simple specie that grows taller than a two story house is rare nowadays. It develops a high branched canopy of evergreen olive drab foliage. The three inch wide leaves are about three feet long.
Modern cultivars stay significantly shorter, with somewhat shorter and less pendulous leaves. Some are nicely bronzed or purplish. Others are variegated with creamy white, pale yellow or pinkish brown. Trusses of minute flowers that bloom in early summer are not much to look at, and drop sawdust-like frass as they deteriorate. Bloom might be greenish white or blushed, and then fades to tan. Most modern cultivars do not bloom much, or may not bloom at all. The gray trunks have an appealingly corky texture.