Introduction to AloesBy Geoff Stein (palmbob)
July 6, 2008
This article is an introduction only to a series of subsequent articles in which I will cover much of what I know (or have made up) about cultivating Aloes in southern California. I am not an expert, but I have learned a lot over the years and I hope to relay relatively accurate information to you, as there just is very little written about this amazing genus and its perfect adaption to the southern Californian climate.
In order to describe these aloes I will have to use a few terms that one might not be familiar with. So the following are a few aloe diagrams to show the parts to which I am referring.
Aloes are made up of rosette(s) of succulent leaves that range in texture from rubbery and maleable to very stiff and liable to break if bent. The leaves range from rough textured to so smooth they are almost like polished plastic. Some are distichous (leaves in two planes only) either when young (commonly), or for the life of the plant (less commonly). Most have leaves with marginal teeth that often are very sharp, though some have miniscule, harmless teeth and some even have none (rare). Some have leaves that also have a lot of thorns on them (just like the marginal teeth, but called thorns if not along the leaf margins) either only when young, or sometimes for the life fo the plant. Aloe leaves can be a variety of amazing colors, though green or blue-green are the most common. Many are spotted, speckled, striped or blotchy.
Typical rosette (Aloe broomii); Aloe suprafoliata, so named because the leaves are stacked upon each other in a distichous fashion when young; Aloe lineata showing more than just typical juvenile distichous leaf pattern when young (both these aloes form normal rosettes as they mature)
Aloes compressa and inexpectata are species that have distichous leaf patterns their entire lives
Aloe affinis showing rather typical, though extremely sharp, marginal teeth; Aloe betsileensis with smaller, dark red marginal teeth; young Aloe excelsa covered in thorns (most lose these as they mature).
Aloe striata, a common species and one of the few with no marginal teeth; Aloe parallelifolia has only a few itty bitty teeth near the base and tip of each leaf
Internodes are the spaces between the leaf bases- Aloe speciosa with almost no internode space; Aloe striata with exaggerated internode space labeled; and juvenile Aloe arenicola, also showing exaggerated internodes
Many aloes spread by growing suckers- some from the base of the plant as in the Aloe distans in first photo, and some at the end of long roots as in the Aloe maculata in second photo (where the suckers show up several feet or more from the main plant); Aloe brevifolia in third photo has suckered so much there is no way to tell which is the original plant
Aloe with true spots, and one with spots/striping, and species with speckling
Aloe belatulla hybrid with super-fine speckling; Aloe aculeata looks spotted, but really has thorns with white bases, so not really considered a spotted species
Aloe rubroviolacea and glauca both have a glaucous bloom on the leaves (you can see where some has rubbed off) that is protective against harmful solar radiation
Aloes are usually identified scientifically by their flowers (often small details in the flower morphology, which, frankly, is a bit beyond my expertise) as many Aloes otherwise can look alike. As you will see below, sometimes even flowering aloes can be impossible to tell apart. The following are some photos and terms used to describe flower shape and structures. I recommend becoming familiar with some of these terms if you want to be able to tell some similar aloes apart.
Aloe bakeri and Aloe mitriformis with labeled plant parts- Aloe bakeri has very open, sparsely flowered racemes while Aloe mitriformis has highly organized short, conical racemes
The entire 'flower' is really called in inflorescence, which is the structure that grows above the leaves with all the colorful flowering parts on it, as well as the stalks that hold up these parts. The inflorescence is made up of the peduncles (the stalks), the racemes (part with the colorful flowers), the flowers themselves (the individual cone or tube- shaped structures with the color) and the bracts, which are thin coverings from which the flowers emerge along the raceme. Some flowers have a single, unbranched peduncle while others are branched (most). Some have conical racemes (probably the most common shape), some are tubular, some are spherical, 'head-shaped' (half-sphere) etc. Some racemes are compact (all the flowers are crammed close together) and some are open (the flowers are very separate).
Sequence of events of a 'typical' Aloe inflorescence (this one is Aloe africana): in the first photo this immature inlforescence shows only the bracts, as the flowers have yet to emerge; second photo the immature, but unopened flowers have grown; third photos shows a close up of the bottom of the raceme where the flowers are starting to mature and open, showing their stamens- almost all flowers open from bottom to top like this one
As flowers open the older flowers dry up and die, eventually turning into fruits (if they have been successfully pollinated) as can be seen in the second photo; third photo is of dried seed pods after all the seeds have fallen out (Aloe vaombe)
Different flower shapes- Aloe arborescens with branched peduncles and conical racemes, Aloe alooides with unbranched peduncles and compact, tubular or columnar racemes, and Aloe andongensis with somewhat open, 'head-shaped' raceme
Aloe compressa 'spherical' raceme; Aloe conifera with a 'corn-cob'-shaped raceme; Aloe marlothii with large, branched inflorescence and unique slanted, one-sided racemes
Aloe littoralis with highly branched inflorescence and long, conical racemes; Aloe maculata with open, head-shaped raceme, and Aloe striatula with a compact, flattened, narrowly-conical raceme
Here are two varieties of Aloe broomii flowers- the one on the right has exposed flowers while the one on the left has bracts that cover the flowers until they open... the two plants otherwise are identical, so it is only through this difference in flower morphology that one can tell the two varieties apart
Close ups of the flowers themselves, showing exposed stamens, often of strikingly different colors from the flowers themselves
Aloe cryptopoda flowers- a typical example of bicolored raceme (unopened flowers one color, and opened flowers having turned another color)
I divided up the Aloes into tree aloes (two articles have already been written about these), the spotted Aloes, which never fail to have me pulling my hair out trying to tell them apart, the stemless South African aloes (separated out mostly because these are the most commonly grown and best covered in the literature), the vining and branching aloes, the miniature aloes, the aloes of Madagascar (a very sketchily covered bunch of exciting and beautiful plants), the grass aloes, and the aloes of mainland Africa/Asia NOT in South Africa (an even more sketchily covered subject in the literature). Many aloes obviously fit in several categories (miniature aloes from Madagascar, or spotted aloes from central Africa etc.), so I put these in one or the other, but not both. There will also be a section/article upcoming on hybrid aloes as many commonly sold and grown aloes don't fit in any of these groups as they are not found in the wild.
In this article I will show some great examples of each to grow in your Mediterranean climate gardens, or in pots if you don't happen to live in such a climate. Most aloes are fairly easy to grow in pots and as long as one provides sufficient sunlight and warmth (and perhaps try to control excessive humidity), one can grow most of the aloes in pots in just about any climate.
The Stemless South African Aloes:
This is a hardy group of plants, with a few exceptions, and amazingly tolerant of a lot of careless abuse in the garden, but only as long as there is sufficient heat and sun. Lack of either and there might be problems growing these species (and all the others as well). The following are some of the more commons species (but certainly not an all-inclusive list)
Aloe broomii Aloe burhii (occasionally spotted) Aloe claviflora, one of the more cold hardy species
Aloe cryptopoda Aloe distans (sometimes included in the spotted species) Aloe falcata (can look a lot like Aloe claviflora)
Aloe gerstneri Aloe glauca (an extremely variable species) Aloe globulogemma and its unique flowers
Aloe hereroensis (sometimes spotted) Aloe melanacantha Aloe peglarae
Aloe polyphylla, a very difficult species in California Aloe petricola Aloe striata (one of the most common species in cultivation)
... and many more
Aloe suprafoliata Aloe vanbellenii
The Spotted Aloes:
Many aloes are spotted for part of their lives, but if they lose those spot as adults, I tried not to include them in this section. I also did not include the spotted aloes that are also branching, or miniature (there are a LOT of those). These, as a group, are about the most durable and hardy of all the aloes (though some blue desert aloes have a lower cold tolerance). They tolerate lots of water and some are amazingly fast growers, going from seedling to blooming adult in just 3 years or more. On the down side, I am at a loss at telling many of them apart, as are obviously many of the sources selling these plants.
Aloe aculeata (though the spots are really white thorns); Aloe affinis (which is sometimes unspotted); Aloe dinteri from Namibia
Aloe ellenbeckii (which could also qualify as a miniature aloe, as well as one NOT from South Africa); Aloe fosteri (a beautiful species) and Aloe greatheadi, THE classic spotted aloe
Aloe duckeri Aloe parvibracteata Aloe harlana (sort of a striped/spotted species)
Aloe hemmingii, one of the most common species, and Aloe maculata, perhaps even more common; Aloe microstigma- a beatiful landscape plant
Aloe parvibracteata Aloe sinkatana Aloe somaliensis (perhaps)- some plants have no spots at all
Aloe variegata Aloe deltoideodonta (also could be put under the Madagascan aloe section) Aloe zebrina
The Vining and Branching Aloes:
Some of the most common aloes in landscape use are included in this group, and most are very easy to grow, bordering a bit on invasive even. Cold hardiness in some of the branching species is very poor, but the vining species in general seem to be about average cold hardiness. Most do well in both sun or partial shade and tend to be fast growers. The following are examples of branching aloes:
Aloe acutissima (another Madagascan species); Aloe arborescens, a very common plant, and Aloe confusa, a very rare one
And these are examples of vining aloes:
Aloe ciliaris Aloe striatula Aloe tenuior
The Miniature Aloes:
there are several of these from all over Africa and Madagascar. Some are difficult and others are no problem at all... but many are not the most ideal landscape plants for the obvious reason that they are small and tend to get lost in the landscape. Most growers of miniature aloes keep them in pots for those same reasons. There are hundreds of hybrids of these miniatures species, both intra and intergeneric. Gasteraloes (not covered here) are very common and popular hybrids that do exceedingly well in cultivation.
Aloe aristata Aloe bellatula from Madagascar Aloe descoingsii, also from Madagascar
Aloe brevifolia (very common) Aloe haworthioides Aloe humilis
Aloe inexpectata (a dinky Madagascan species); Aloe jucunda (a common species that looks like a miniature Aloe hemmingii; Aloe juvenna- another very common and hardy species
Aloe krapohliana Aloe longistyla Aloe parvula
One of my personal favorites, Aloe pearsonii
Aloes of Madagascar:
For reasons of lack of information, this will be a very incomplete introduction as many of these species are so rare and I have no personal experience with many of them... many species from Madagascar I have not even heard of. But in general these are some of the most colorful and fascinating species, as well as some of the more marginal ones that can be grown in southern California (much of Madagascar is far more tropical than southern California). These might be good aloes to try growing in warmer, more humid climates such as south Florida or Texas, though they may need some rain protection there.
Aloe capitata Aloe conifera Aloe divariacata
Aloe ibitiensis, an attractive lined smaller species; Aloe imalotensis and Aloe lomatophylloides (all the Lomatophyllum species were moved to Aloe recently
one of my favorites (so far... not gone through freeze yet): Aloe altimatisiatrae
This is my least favorite group as they are not all the different looking (again some exceptions), though some have spectacular flowers. These plants, in general, seem to prefer protection from the sun. They are not highly useful as landscape plants for the same reason the miniature aloes are not (get lost in landscaping) but still make decent potted plants.
Aloe cannellii Aloe cooperi Aloe inyangensis
Aloes from mainland Africa but NOT South Africa:
This is a poorly understood group of aloes (by me) and the least common in general in terms of cultivation. Many of these are similar looking, non-descript stemless and nearly colorless plants of beige, tan, pale green or nearly white. Few have spectacular flowers, either. However, I have become very interested in these and their lack of coloration actually enhances their landscape appeal in many cases. Some are a tad sensitive and many seem less tolerant of overwatering or cold than are the aloes from South Africa.
3 uncharacteristically brilliantly colored species: Aloe cameronii, Aloe congolensis and Aloe dorotheae
Aloe elelgans Aloe fleurentiniorum
Aloe ortholopha Aloe porphyrostachys Aloe rubroviolacea
Aloe secundiflora Aloe somaliensis Aloe tomentosa
Aloe powysiorum Aloe vacillans Aloe vera, the most common aloe of them all
This is a group of cultivated plants, some extremely common in the nursery trade, that are not found in nature. Not included in this group are rarely hybridized plants of two random species, or this list could be nearly endless.
3 fairly common hybrids in cultivation: Aloe Black Beauty Aloe Blue Elf Aloe Doran Black
For more on the tree aloes, not discussed in this article, please go check out these articles: http://davesgarden.com/guides/articles/view/212/
And if you want to see more about aloe flowers, go to these articles: