So, up in front, this will a way to save the progress of it, and open to critique(but please PM me instead of writing here).

I am writing this article as way to address the confusion found among Cactus & Succulent newcomers as well as those not all that well informed on the subject

I've opted to spare the reader the intricacies of taxonomic classification, in short it refers to researching the genetic link of species via molecular phylogeny(DNA comparison), at least by the newest standard.
Plants are going to be clumped by some form of common denominator, usually in the form of Family (eg. Cactaceae, Apocyanaceae, Asparagaceae), or in the very least under Genus(Euphorbia, Ceropegia), with a few terms being thrown in between such as Tribe or Sub-Family.
I will begin with some of the most popular and widespread: Aloeae, sub family of Asphodeloideae

The Sub-Family Aloeae has its native habitats spread out across Africa and the Arabian Peninsula with some species being found on islands in the Indian Ocean. Habitat is variable as well, ranging from the Namibian Desert, to the rocky outcrops of Table Mountain in South Africa, all the way to Soccotra Island in Yemen. It consists mainly of leaf succulents whose Genera include: Aloe, Aloiedendron, Aristaloe, Gonialoe Aloiampleos, Kumara, Haworthia, Haworthiopsis , Tulista, Gasteria and Astroloba.
Main features of this family are the mainly red to yellow flowers poking out on the inflorescence , which when young is vague shaped like and asparagus shoot , and like all growth emerges from a rosette growth point.

Other features include spikes on the leaf margins (from woody hard thorns to soft fleshy points resembling cilia) , which is present on a lot but not all species. Leaves are filled with soft spongey or gelatinous transparent tissue.
Species vary in size, with the most diverse being Aloe itself.

Single stem treelike Aloe marlothii

Clump forming and small Aloe juvenna which also shows spots sought after on lots of species and cultivars

bushy Aloe arborescens

unnamed hybrid found in a market, one of many cultivars, is sought after its unique bright red growth on the leaves and leaf margins. This feature and the maculation is often mixed and matched in various hybrids.

Multi-branched Aloidendron barberae, the genus also possesses stem succulence within the trunk.

Kumara plicatilis with its unique foliage

Haworthia features leaf windows, like some Aizoaceae members

Gasteria wrinkles. The coarse surface has been taken to new levels with this hybrid.

Haworthiopsis features unique ridges on its leaves

The loosely related Bulbine genus and the similar Bulbinella also feature some leaf succulence but they are mainly geophytes(shown here is Bulbine frutescens)

Other members of the Asphodeloideae are non-succulent, with the genus Kniphofia's flowers bearing a resemblance to those of Aloe species.

So you are re-inventing the wheel?

The Aloes Database

Part 2
The second group worth mention would also be rosette monocots, the family Asparagaceae.
For all intents and purposes , its succulents are split into 3 main groups: Agavoideae , Nolinoideae and Scilloideae.
Agavoideae are leaf and stem succulents coming from the Americas, with fibrous leaves, growing in rosettes.
Agave itself is the star of the show, a diverse mainly stemless monocarpic genus of plants whose main feature is letting out a tall inflorescence several times the height of the plant.

Immature flower spike on A.salmiana , 3m tall/10 feet(aprox.) . Spiny leaf margins and spike on the leaf end are typical of most Agave

Mature spike on A.attenuata , about the 3,5 m /13 feet(approx

other Agave forms include

the popular Queen Victoria agave, no serrated leaf margins and compact growth

Agave bracteosa, with thin and flexible leaves

Agave striata, even thinner leaves

Formerly under the genus Manfreda, the maculated species are often hybridized with larger plants for a stunning display
The genus Agave also includes several tuberous plants, but they are non-succulent.
The second most important and more widely cultivated genus is Yucca. Unlike Agave, they are polycarpic, have thinner leaves, and only a few have serrated leaf margins(but as apparent like on most Agaves). Some posses woody trunks and adopt a treelike habitat. Flower spikes are smaller in general, but the flowers are larger, and cream-white.

To compare the two, side by side , Agave americana(the most common and archetypal agave) and Yucca rostrata, a thin-leaved tree type of yucca.

Immature inflorescence on Yucca gloriosa

Variegated variety in bloom

opened flower

Another tree type, probably Yucca aloifolia
There a few more genera in Agavoideae which are succulent. Those being the agave-lookalike Furcraea



whose flower does not look like that of agave(large and downward pointing)


Another is the obscure Beschorneria

There are 2 genera related or similar to Yucca, the first being the monocarpic Hesperoyucca

and Hesperaloe


..ok, that should suffice for today.

The group Nolinoideae has plants with appearance mirroring those of the Agavoideae, with difference within the inflorescence and the lack of terminal spine on the leaves. The group's namesake Nolina features a type of stem succulent/xeric plant similar to the Yucca-rosette growing stemless or treelike.

with a vastly different flower spike

Nolina itself is not widespread in cultivation, unlike its popular cousin, now split from the genus(but often still called under the old name) - Beaucarnea

Its unique feature is the existence of a caudex under a swollen trunk on what would be similar to Nolina. Both of these plants originate from North America.
If Nolina was the counterpart to Yucca, the Genus Dasylirion would be the counterpart to Agave, with most species bearing a sharp, hook-like serrated edge on its leaves, and is generally stemless. Also from North America

The oddball within this genus is Dasylirion longissimum which resembles its relative Nolina, but has a vastly different flower spike.

The most popular and widespread genus of this group ,however, is Dracaena, whose member species span all across the tropics, and are wide popular for cultivation. Originally the genus' succulents included species like D.draco and D. cinabarii (dubbed the Dragon's Blood Tree) , but recently the predominantly succulent Sansevieria has been included in Dracaena.

Canary Islands Dragon Tree

Sansevieria flower
And this is where I cut for now

The last member being Scilloideae features mainly geophythic bulbous or tuberous succulents that come from mainly from the dry-lands of Southern Africa.Genera include Ledebouria, Drimopsis, Albuca, Bowiea and possibly others.

Maculate succulent leaves on Ledebouria

Ditto on Drimopsis

The next monocot family containing succulents is somewhat more familiar to the bulb growers:Amaryllidaceae
While most species under this family do not figure as succulents, a couple of species and genera do share xeric habitats with that of Aizoaceae(mesembs) as well as those native to other similar habitats and have some succulence within their leaves.
Genera bearing succulent species include: Haemanthus, Rauhia, Boophone, Clivia, Scadoxus among others.

Shade grown clivia

My own Haemanthus albiflos, succulent leaves.
Most of these have some sort of underground structure(bulb or modified stem) that lets them weather out the most of the harsh conditions which come with their habitat(by often having as little of the plant exposed as possible aboveground ) , often retreating to dormancy should the need arise. Flowers are often in a group atop a inflorescence, and vary in size and color, in habitat often during more favorable times.

The last major monocot succulent group, Bromeliaceae has been subject to debate whether several species are actually succulent, or not.
This minority involves terrestrial bromeliads growing in arid conditions in the desert and semi-desert regions of the Americas, with species such as Puya, Dyckia, Hechtia, Deuterocohnia among a few others. All species have hard , spiny and waxy leaves, growing in mostly stemless rosettes, which let out a tall inflorescence, and perform CAM photosynthesis. However, most have not developed an explicit form of storage tissue, at least not in a tangible sense. Other species and genera are terrestrial or epiphytic tropical plants.


Though sister genera and of similar appearance, flowers easily tell apart Dyckia with its vibrant orange and sparse larger flowers from its white or pink shaded profuse blooming Hechtia


A bushy cushion plant Deuterocohnia

Patch forming Puya


Unidentified xeric bromeliad

Unidentified terrestrial bromeliad

The first major Dicot family which containing succulents covered here would be the Apocyanaceae. Generally a widely distributed family, most species can be found in the tropical areas of most continents. The main feature of this group is the unique and typical flower structure, 5 sepals surrounding a unique pentagonal structure surrounding the pistil and stamens. Succulent members are very variable, with succulent vines bearing tubers and cactoid clumps with carrion flowers to small deciduous spiny trees. While the majority of the plants of interest in this group are found in the Ceropegieae group of the Asclepiadoideae sub family, other popular genera are scattered throughout its many other subfamilies.


Caudiciform Adenium which are native to Sub-Saharan Africa and the southern part of the Arabian Peninsula. Often under the name 'desert rose'. A close relative to the Oleander.




Pachycaul and caudiciform adenium, with members from Southern Africa and Madagascar

Stem succulent Plumeria, from the Americas. There are other genera including Carrisa, but are not worth mentioning

The other group has more extensive modifications to the flowers. Recent studies have placed a lot what of used to be Stapleideae under the Genus Ceropegia. There are other Genera remaining separate as well.



A trailing succulent vine and a hanging plant-what is considered "original" Ceropegia




Species of what used to be Stapelia, Orbea, Edithcolea and Stapelianthus , cactoid stem succulents(prostrate or erect) with (as the photos suggest) carrion flowers.Mainly from Africa. Genera like Hoodia, Huernia, Brachystelma ,Quaqua, Caralluma as well as the aforementioned can still be found under their old name in cultivation despite their recent reclassification.

Other aclepiad succulents are

the vine/trailing Hoya

And Fockea. Which would be the massive grey blob of a caudiciform plant.

These ones need some work...

Next up would be everyone's favourite and most famous(and usually the most misunderstood) succulent group:Cactacae- THE Cacti. From 1cm/ 0.5 inch buttons to 19m/30 feet giants, possibly having hundreds of branches. Cacti have it all: trees, poles, barrels, vines, creepers, canopy epiphyphtes, dense shrubs, mounds, clumps, spheres, pipes, torches and more! Now, you may think- if a plant is green swollen succulent stem, has some sort of thorns or spines, it would be a cactus by default, right? Well, cacti have one very important feature which sets them apart:areoles which are sort of growth buds and an all in one organ that appears on the plants stem, ribs and tubercules. On these areoles spines can be found, made from modified leaves, and here it branches from and flowers emerge. Cacti come fromt the Americas, bar one species found in Africa

Other plants have modified ligules, sterile peduncles, thorns, leaf remnants or other type of modification involving tubercules. Most of these are Euphorbia and Ceropegia, and a few Kleinia members
The second, also important feature is the flower, only similar to those of Aizoaceae(mesembs)

To start off

This group , despite appareances has a few succulent members, has areoles, and is a cactus. Pereskia is a solitary genus, branching off at the bottom of the Cactaceae tree. Features vines, shrubs or small trees, filled with leaves and spiny areoles. Ones with the least amount of modification, and the most obscure.
https://garden.org/mail/read/1...
The second group, Maihuenia, is rather obscure in cultivation. The genus encompasses a few species of a short stem succulent, covered in leaves and spines, forming mats in the cold areas of patagonia.

The third group, is rather more expanisve, the Opuntiads. This groups main feature is the focus on cladode growth(short section of stem , separated in segments), but not on all plants to an extent , and defining feature are the glochids, small spine like formation that cause severe irritation upon contact.
We have the cylindropuntiads(Cylindropuntieae), with genera having segmented, cylindrical stems. Species are Cylindropuntia, Grusonia, Pereskiopsis and Quiabentia


The main group, Opuntieae , has the following genera: Consolea, Opuntia, Tunilla, Tacinga, Miqueliopuntia . Main feature of this group are flat cladodes, with areoles showing up on the flat sides as well as on the edges(unlike the epiphytes)
Opuntia, being the second largest genus of cacti, has its flat pads take all kinds of shapes, almost round like pancakes, oval, like elongated tongues, hearts, deltoids or rhomboids . Habitat is from a sprawling hardy rock lover to small trees. Invasive, popular in cultivation, widespread, and relatively easy.




Next group, Tephrocacteae, has 2 genera, Tephrocactus and Maihuenopsis. Small, segmented plants.

Another group is the Austrocylindropuntieae, with members Austrocylindropuntia and Cumulopuntia. Some of these grow in an elongated stem, closer to the other cacti groups,

А.subulata, the most widespread species in cultivation. A thorny shrub, but less noxious than most of its relatives. Often found in monstrose form.

To be continued...

The core of the Cactaceae consists of the Cactoideae sub family. Genera here are often disputed with their classification, being clumped and separated, split and joined and renamed with each study. For the average grower this group contains 3 main types of plant -globular and /or elongated bubble cacti, columnar cerei, and epiphytes.
In laymans terms we are going to look at
-Cacteae, a tribe of bubble and barrel cacti from North America
-Cereae, a tribe of cerei and bubble cacti from the Carribean and parts of South America
-Echinocereae, a very diverse and widely distributed tribe, having mainly cerei, with a few epiphytes and bubble cacti in between(this group is the one with the heaviest makeover) B
-Trichocereae, a South American tribe of cerei and bubble cacti
-Notocacteae, a tribe of exclusively bubble cacti from south america
-Hylocereeae, epiphytes from Central and South America
-Rhipsalideae, segment growing epiphytes mainly from South America
-Browningieae, South American cerei.
The oddballs here would be the monotypic and isolated Blossfeldia

Whose members are only 2cm when mature, if ungrafted
and the obscure Lymanbensonieae(formerly Calymmanthium)

Tribe Cacteae, popular for several genera




The barrel group, Ferocactus, Echinocactus, Biznaga and Homalocephala(disputable) .
Barrel shaped, flattened globular or clumping. Spines are colorful(yellow, red , black , grey and their mixes) and have ridges, when young the plants are tuberculate(as shown above) , when older they form ribs. Some have hooks.