Succulents Are A Diverse Group

If Agave are succulents, are closely related Yucca also succulents?

There really is no way to neatly classify succulents. Many are spiny cacti with fleshy stems without recognizable foliage. Others are euphorbs (related to poinsettias) that may resemble cacti, or may instead have fragile leaves on fleshy stems. Aloes and agaves have bold rosettes of fleshy leaves that obscure their wide basal stems.

The most familiar succulents are small docile perennials, like the many varieties of jade plants and iceplants. Some are flowering perennials like begonias. A few are even grown as annuals, like busy Lizzie (impatiens).

So what do succulents have in common? Well, that is a good question that is open to interpretation. Most would agree that succulents have some sort of fleshy succulent parts for storing water through dry weather. These succulent parts are most often leaves or stems. Yet, yuccas, dracaenas and ponytail palm that are no more succulent than palms, are considered by many to be succulents like related aloes and agaves.

Many succulents are remarkably easy to propagate vegetatively (without seed). Most aloes, some agaves and many yuccas produce pups, which are basal shoots that can be separated as new plants. Agaves that do not produce pups while young will likely produce many pups after they bloom and begin to deteriorate. (Individual rosettes die after blooming.)

Despite the nasty spines that make them difficult to handle, cactus that produce multiple trunks can likewise be divided. Cactus can alternatively be propagated as large cuttings; but because they are so fleshy, should be left out for their cut ends to dry and ‘cauterize’ somewhat before rooting. Many euphorbs behave much like cacti, but are even more hazardous to handle because of their very caustic sap.

The majority of small succulents, like the many jade plants and iceplants, are notoriously easy to propagate by cuttings.

Thread Agave

Agave generally excel in chaparral climates.

Many species of Agave and Yucca should probably be more popular here than they are. Several are endemic to desert or chaparral climates. Once established locally, they may survive without irrigation. Occasional watering through summer only improves their foliar color and vigor. Except for gophers that might attack from below, not much offends them.

The primary deterrent to their popularity is their dangerous foliar spines. Many species of Agave and Yucca grow too large to not become obtrusive within compact home gardens. Consequently, their striking but hazardous foliage can be difficult to avoid. Fortunately, a few species such as thread agave, Agave filifera, remain proportionate to home gardens.

Thread agave develops rounded foliar rosettes that are less than three feet wide and two feet tall. Evergreen leaves retain silvery impressions of adjacent leaves. Although growth is generally slow, vigorous floral stalks may grow rapidly to ten feet tall during summer, to bloom during autumn. Pups begin to replace original rosettes prior to monocarpic bloom.

Six on Saturday: Joshua Tree

Yucca brevifolia is commonly known as Joshua tree. It is native to the Mojave Desert. It is very rare in home gardens because it is so extremely susceptible to rot with irrigation, or even where it gets more rain than it is accustomed to in the Mojave Desert. Besides, it is very difficult to work with, and even with impeccable maintenance, even the healthiest of specimens develop weirdly and unpredictably irregular form that too many find to be unappealing. Nonetheless, whether appealing or otherwise, whether in a landscape or in the wild, it is a fascinating species of Yucca. Rhody and I encountered these Joshua trees and many others west of Boron last Thursday.

1. Joshua tree is the tallest tree in this region, but does not get as tall as utility poles. The scarcity of moisture limits vegetation here. That is not wildlife in the lower right corner.

2. Zooming in on the specimen to the right in the previous picture reveals that there are many more in the distance. Many are solitary. Most live socially, in otherworldly forests.

3. If there were an exemplary Joshua tree, it might look something like this. The shabby specimen in the background to the right is also rather typical. They are weirdly variable.

4. These short and rigid leaves are extremely sharp! They look somewhat like the foliage of common giant yucca, but are very difficult to handle. Joshua tree is better in the wild.

5. Old foliage decays very slowly. It folds back and lingers on the limbs like this for many years. Joshua tree grows very slowly, so this foliage may have been like this for decades.

6. Trunks eventually shed deteriorated old leaves as they widen and develop this roughly textured exterior that resembles bark. Again, that is not wildlife in the lower left corner.

This is the link for Six on Saturday, for anyone else who would like to participate:

Mound Lily

Mound lily cultivars are generally variegated.

A few of the fifty or so species of Yucca go by the names of Spanish bayonet or Spanish dagger. Both common names apply to Yucca gloriosa. However, only this single species is also the mound lily. Most other Spanish bayonet and Spanish dagger are from deserts or chaparrals. Mound lily is from southeastern North America, so likes periodic watering.

If that is not confusing enough, the curved leaf yucca, which had been Yucca recurvifolia, is now Yucca gloriosa var.(iety) tristis. It has distinctly pliable leaves with a matte surface texture, and is rarely variegated. Mound lily has stiffer and smoother leaves that are more likely to be variegated. It had been rare, but is becoming one of the more popular yuccas. 

Although it does not grow fast, and takes many years to form stout trunks, mound lily can eventually get taller than six feet. Taller floral panicles rise above the densely evergreen foliage. The small and pendulous flowers are pale white, perhaps blushed with brownish purple and pink. The leaves are about a foot or two long and maybe three inches wide, with very sharp terminal spines.

Six on Saturday: One Yucca

Of the fifty or so known species of Yucca, I formerly grew all but one. I still am not certain if the single species that I lacked, Yucca flexilis, is a real species or a synonym for another species. Of course, some species of Yucca might be considered to be subspecies of others. The genus is complicated. So is identification of its species. That is why I am not certain of the identity of the one Yucca that I got a picture of this week. Actually, only one of my Six, which live with the unidentified Yucca, are identified.

1. ‘Sedums, Dahlias and Hayfever’ might have something to say about this unappreciated mess. A neighbor left these for the gardens. I can identify only that ‘Angelina’ sedum. Oh, the shame!

2. Pups such as this could suggest that the associated primary rosette intends to bloom soon. If so, the pup will replace the original. I do not remember what species or cultivar of Agave this is.

3. This young pup appeared about six feet from its associated primary rosette, so is less likely to be an indication of impending bloom. I do not know the species or cultivar of this Agave either.

4. Agave attenuata is easier to identify. It has been here since December, but has not done much. I got a pup from it prior to planting. Later, another rosette was acquired from another source.

5. This might be Dasylirion wheeleri. I am rather certain of the genus, but not so certain of the species. Those little teeth on the foliar margins remind me that I do not want to weed around it.

6. Could this be Yucca whipplei? Its foliage certainly suggests that it is. However, the common sort should not develop such crowded rosettes. It could be a more densely clumping subspecies.

This is the link for Six on Saturday, for anyone else who would like to participate:

Giant Yucca

Common giant yucca is uncommonly bold.

Like so many of the plants that became too trendy at one time or another, giant yucca, Yucca elephantipes, had gotten a bad reputation. Some people still consider it to be cheap and common. The real problem though, is that some of the countless giant yuccas planted over the years went into situations that can not accommodate their massively distended trunks. Only a few of the largest specimens are taller than a two story house, and not many get broader than tall. However, their several sculptural trunks are remarkably bulky and flared at the ground.

The somewhat rigid and narrowly pointed leaves can get as long as three feet, and as wide as three inches. Foliage is typically slightly yellowish green, or richer green and a bit floppier in partial shade. Spikes of white flowers that bloom in spring are tall enough to stand just above the foliage, but are usually too high up to be too flashy. Individual flowers are actually only about an inch and a half wide. The bold form and texture of giant yucca work will with other bold plants like giant philodendron, various agaves and various cacti. Shoots and stems of any size that need to be pruned away can be stripped of lower leaves and ‘planted’ wherever new plants are wanted. They only need to be watered regularly until they develop roots like really big cuttings.

Curve Leaf Yucca

Curve leaf yucca can be variegated.

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.

Spectacular Bloom Can Be Lethal

70510thumbAfter 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

71018Dracaena 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.