Pachypodium occurs as plant genus that belongs to the dogbane family, Apocynaceae. Pachypodium comes from either Greek pachy (thick) & soapbox (foot), hence meaning heavy-footed.

Genus characteristics

A lot Pachypodium come succulent plants that exhibit, to varying degrees, a morphological characteristics of pachycaule trunks and spinescence. Which are actually a virtually all general features of the genus and can be considered distinguishing characteristics.

A pachycaule trunk occurs when morphologically hypertrophied trunk that places water supply then as to endure seasonal drought or intemitent periods of root dessication in contaminated, dry, & jolting conditions. Whereas there exists outstanding variation in the habit of the plant body, a lot Pachypodium exhibit pachycaul incubation. Variation around habit could range from either dwarf planate plants to bottle molded bush to dendroid-shaped trees.

A 2nd general characteristic of Pachypodium is spinescence, or even with spines. A spines are clustered as much as either pairs or even even triplets by having these clustering typically intended inside rings or whorls around a trunk. Spines emerge using leaves, & rather leaves develop for the short time period prior to stopping incubation & hardending. Since spines don't regenerate, weathering & abrasion might have on away just about a immature spines from either older specimens, departure smoothe trunks & branches.

To a few extent, branches are the characteristic of the genus. A few caution is warranted within all over-generalizing this characteristic. Pachypodium namaquanum is often branchless. Pachypodium brevicaule has no clear branches, & indeed might use evolved an choice to branching in the form of nodes from either which leaves, spines, & inflorescences emerge. Within general Pachypodium own couple branches. Since a environmental stresses & factors that contribute to branching might alter widely possibly around microscopic areas, person plants of the equivalent mintage exhibit wide variation around branching morphology.

Unlike numerous members of the Apocynaceae, including some members of the superficially similar Adenium, Pachypodium mintage don't exude the milklike latex. Like, a sap is always clear.

Morphology
A morphology of the genus Pachypodium varies significantly both inside & between coinage & is extremely responsive to its quick circumferent microenvironment. Pachypodium don't to a fault respond morphologically to big vegetive zones. For instance, Pachypodium may occasionally occur inside prehumid vegetive zones in which the taxonomic category might call for the suitable home ground in the jumpy, sunny inselberg jutting above the humid canopy of the outdoors.

Morpholigically, Pachypodium may be extremely flexible inside organization. Branching, in case present a least bit, may be from a base of the plant or even at the crown. Freeform branching occurs as morphological adaptation to factors of the quick microenvironment which, by their diversity, account for the wide range of habits:

planate dwarf metal money less than Viii cm tall however reaching 40cm in diameter bottle- or even ovoid-shaped bush to Quatern m tall each branching & unbranching cigar- & cactus-such as trees to 5m tall.

Despite microenvironmental variation, Pachypodium come universally lush & universally exhibit pachycaul trunks. Pachypodium come commonly spinescent, however single variation within spinescence too when weathering/abrasion potty symptom is plants by owning couple of whenever any spines.

Adaptive mechanisms

To talk all about adaptive mechanisms of Pachypodium, one obviously invokes the discussion just about speciation, or variation around species. Pachypodium develop deuce general succulent characteristics to respond to the xeric landscape: "pacycaule trunks" and "spinescence." Eventually these are as well unambiguously "flexible" & "strict" within its organisational, structural morphology, which has aided it in responding to the challenges of geological, xeric landscapes. Variation among a mintage is therefore important, using exception to the Pachypodium rosulatum aggregates, among their morphology that the discussion of adaptative mechanisms leads to a wonder:

"How do taxa became species?"

Pachypodium come universally lush plants. Hence a genus employs 2 types of adaptive means to xeric, isolated, geological conditions of the landscape, especially around Madagascar:

Pachycaule. the plant develops a pachycaule trunk that retains water. A trunk, also when branch, is abnormally thickened into various shapes. Inside this genus, these shapes range from either dwarf plants to bottle-shaped shrubs and cigar-like trunk for the tree. Using deuce mintage, a adaptation to evolve geophytic trunks, or even trunks that come below a soil's surface can be found. However morphologically, these geophytic trunks are caudexes, hypertrophied stems or even trunks that places a body of water. It should never exist as misunderstood for roots, because a enlargement occurs above a point in which a roots branch off a independent axis (the crown) or trunk. This evolutionary adaptation of the geophytic trunk occurs as response to the home ground of the mintage given to its average landscape conditions.

spinescence. Pachypodium produce utilize of spinescence as an adaptive mechanism responding to the landscape. Adaptively this spinescence is listed to different degree inside various mintage to collect moisture from fogs and dews. A spines point withinside tons angles, come paired or even in sets of threes in which a third spine is unequal, & so captures wet that might drip directly down to the soil beneath a plant from either the branches & twig. A degree of spinescence demonstrates a degree to which mintage rely in spines as a means to collect moisture from microclimate conditions, such as localized dews or fogs within microenvironments, & drip to the soil immediately below the spine in a branch or even sprig. A falling moisture immediately around a plant saturates a soil. The superficial rootage might typically produce to require benefit of this source of wet.

A conception of "micro-endemism" plays an important role in that relationship between adaptation mechanisms & speciation. It suggests the certain little shell "nativeness" by virtue of originating or even occurring naturally around the particular place or location. A landscape of Madagascar is a hone lesson of "micro-endemism" for coinage of Pachypodium & more taxa. 3 factors may be seen to attribute speciation, or even a occurrence of coinage diversity, via adaptative mechanisms to accelerated evolution as it occurs within a xeric landscape & climate.

(One) A variation of geology & topology withwithin dry climates is thought to have a greater result upon plants than in areas by owning high rain. Xeric environments come so thomas more demanding of adaptative mechanisms to help in the plant's survival than in situ in which rain is plentiful. A sir thomas thomas more a demanding, typically a more "mechanized" or even "mechanisms" come required to help a plants' survival.

(Two) A geological formations of locally xeric landscapes decompose populations of organisms, i.e. plants, into smaller groups, in which for each one class action may ab initio interbreed however, by having period, grow fresh genotypes and cannot become breed by having exception to natural hybridization. Localized geology becomes harder to cross over for the given people to exist as "continuous" in the xeric geologic landscape, because other demands come located on the people. So, populations come broken down into little units in this landscape. Groups of the original people be placed to unique microenvironments within a landscape. Accordingly measures to adapt to these microenvironments turn into additional singular to the isolated home ground. Adaptative mechanisms come listed and then when to help a survival of the plant class action. This adaptation inside time, in a portion, leads to speciation in a home ground, or even diverse coinage through the spectrum of the landscape.

(Three) Taxa tend to get specialised xeromorphoric structures at a select few architectural level within arid, geological & topological landscapes, where the strategy of the "flexible" & "strict" architectural, organisational morphology at various levels of structure for Pachypodium becomes appropriate to succeeding in the isolated, specialised landscape. This strategy is seen in the patent flexible variations of habit within metal money of Pachypodium when however it is "strictly" xeromorphic pachycaule trunks intended to conserve a lake for dry periods. At an additional level of structure, viz. that of organs, i potty understand that dew and fog dripping spines are examples of the xeromorphic adaptative mechanized organ responding to microenvironments.

These new created metal money from either in a xeromorphic landscape require in different characters when reactions to the habitat. E.g., there exists an benefit to morphologically getting into bottle-shaped "shrubs" inside which a plants survive in open, sunny microenvironments in top of poriferous sandstone. Little completion lives for height in a home ground. Also, in which competition for resources is further competitive--two in a total of mintage & the height of surrounding plants--there are days while these are to the benefit of the plant to produce into dendroidal, arborescent “trees.� This development is because these particular Pachypodium must compete using more plants for resources inside the dry deciduous woods, composed of, perchance, arboreous Aloe, members of the Didiereaceae genera--Alluaudia, Alluaudiopsis, Decaryia, & Didierea; tons autochthonal to Madagascar--and Uncarina metal money, e.g..

the adaptative mechanism around a morphological form & an ecological response to home ground come generally manifested together at it used to be that for the genus Pachypodium.

Examining Pachypodium reveals characteristics of various organs that adapt to the microenvironment. These adaptations, variations in habit, trunks, branches, branchlets, spines, leaves, or flowers, are plentiful around demonstrating how else Pachypodium as a genus fosters greater variation within its speciation. A manner where speciation occurs inside Pachypodium, so, is apparent: adaptative mechanisms in the morphological level respond to the microenvironment of Pachypodium home ground. A genus' unique organisational, architectural morphology shapes plants that come extremely, adaptively responsive to their quick, circumferent, microenvironments. A duplicity of an adaptative mechanism that is at when "strict" & "flexible" at differing levels of plant physiology, or even structure, has granted Pachypodium a ability to develop inside a landscape into variations that fulfill an ecological niche as various metal money.

A hypothesis of micro-endemism, therefore, states that speciation occurs withinside microscopic specific home ground when assisted by adaptative mechanism occurring in geologic, topographic, & climatical isolation. Geologically & topographically, plant populations around xeric climates come broken down into little groups. the microclimate responds to the given location transforming it into a home ground. Isolated , a duplicity of organization around Pachypodium form across geology & location important variation in which across evolutionary instance the recently mintage may acquire, whenever does'nt stand developed. A development of fresh coinage is across, inside section, a adaptative mechanisms of pachycaule & spinescence too when nonindulgent & flexible structural organization at various levels of plant physiology.

Taxonomy
Number of species
There are currently Twenty-five known mintage, of which Twenty came from either Madagascar, where isolated landscapes and micro-environmental conditions have produced extremely specialized species. A mintage account continues to develop when Pachypodium menabeum has been resurrected from invalid taxonomy & Pachypodium makayense added newly to the listings. 1 might speculate that inside regions like Madagascar, there might however exist as unidentified mintage that come confined to one rough rock outcrop or even an inselberg.

Affinities within the Apocynaceae
A personal Apocynaceae prior to it involved Asclepiadaceae experienced Iii genera that can be considered succulent plants: Adenium, Pachypodium, and Plumeria. A 1st both genera (Pachypodium and Adenium) are typically assumed to use at times closed association by owning both more. Studies; yet, one ii genera reveal that it is non when intimately close when it used to be that thought.

Notwithstanding, the learn of key characteristics of the taxonomic group & the cladistic study of the subfamily Apocynoideae and a personal Asclepiadaceae (before its merging using a Apocynaceae), demonstrates that this closed association is not warranted. Confessedly, two come lush plants & pachycaule. Based on data from Leeuwenberg yet, Adenium is maintained in a subtribe Neriinae, laid underneath the tribe Wrightieae whereas Pachypodium is placed beside a in a subtribe Pachypodiinae, inside the tribe Echiteae. Though related, these taxa means that them are non intimately related.

Distribution and habitats
Distribution
Pachypodium come endemic to Madagascar and continental Southern Africa, i.e. Angola, Botswana, Mozambique, Namibia, South Africa, Swaziland and Zimbabwe.

Habitat
Within elevation, Pachypodium inside each mainland Africa and Madagascar grow between an altitude of sea level, where occasionally species grow in sand dunes, such as Pachypodium geayi, to 1600 m (5249 feet) for Pachypodium lealii in southern Africa and 1900 m (6234 feet) for Pachypodium brevicaule in Madagascar.

Inside continental southern Africa, a extreme temperatures range from -10°C (14°F)inside occasionally locations to up to 45°C (113°F). Whereas within Madagascar, using non such a great temperature amplitude, a temperature ranges from either -6.3°C (21°F) to 40°C (104°).

The generalization all about precipitation regimes for both southern Africa & Madagascar doesn't stand great deal meaning because a home ground of Pachypodium change and then greatly sustaining the wet regime. Inside occasionally web pages, Pachypodium receive annually from either when little when 75 millimeter (Ii.95 inches) from either the southern a portion of Africa to a high level of 1985 millimeter (78.Xv inches). The precipitation regime for the coinage of Pachypodium, so, depends upon the home ground's location relative to the influences of the Atlantic and Indian Oceans & a various chain of southern continental Africa and of Madagascar.

A genus grows inside areas in which there are important periods of dry months that range from 5 months to tenner months. It would seem belike that the Atlantic & India Oceans pay a major role in the creation of weather condition contributory to rainfall, not to mention mountain ranges.

Pachypodium grows around various types of substrates. A few mintage single develop around of these substrate whereas more may develop around many. the degree to which the taxonomic group could develop within a given substrate seems to determine how else specialised its habitat is within the landscape and climates. In outcropping, steep hills, & inselbergs, a plants come subjected to fluctuating moisture, high winds, and temperature extremes. Lone plants sustaining favorite adaptations to exposure & extreme drought may exist, let alone thrive, in these studied geologic home ground. Pachypodium root within cleft, fissures, and crevices of people bumpy formations. A non-succulent roots penetrate deeply into a acuminated soil, mineral, and humus in these crevices. Wet is entity seep deep into these crevices. Super little transpiration occurs. Therein manner, jolting substrates provide wet in the home ground. This saturation of crevices potty lone occur, even so, in case there exists non an considerable runoff from either a rock's surface & whenever there exists abundant ticket soil in the cracks that, successively, locate water supply. A substrate, therefore, plays the critical role in the creation of micro-environmental "arid islands."

S& readily store a water supply because these are taken higher easy and there exists less evaporation except for the top layer. Super deep sand; nevertheless, has a condition of oozing. However within moderation shallow & deep sand substrates develop water system available to Pachypodium. Sustaining shallow sand substrates, Pachypodium develop in sand dunes touching a sea. around which a body of water is in deep sandlike substrate, Pachypodium develop in sand "over" laterite red soil. Laterite soil occurs as largely impermeable soil that traps a lake for the apply of the flora that include Pachypodium.

Protection status
Internationally Pachypodium come protected under a CITES treaty. Based on data from either it, members of this genus just can not exist as collected from autochthonous, native locations in a landscape. It is does'nt easy, readily imported & exported between nations either. A protection afforded per CITES pact reactions to 2 issues:

a esteem the genus has inside Collector's & Nursery Trade. When extremely prestigious plants, lush enthusiast want to collect supplementary & extra metal money & cultivars. In the instance of Pachypodium, seed, seedlings, and possibly matured, nursery-grown specimen plants come as luck would have it available readily around Nursery Trade.

Destruction of the genus's autochthonous habitats, e.g. across agriculture.

Extinction of identified species seems however improbable, when a collection of seed & a cultivation of a plant safeguard the genus.

History of the genus
A early history of the genus Pachypodium demonstrates the average run of the taxonomic category becoming the freshly genus. At the start debate occurred all over whenever Pachypodium belonged to the genus Echites or if it constituted the separate genus. Pachypodium were number 1 published as a unique genus, separate from either Echites, by Leandley in 1830.

So a debate centered on the nomenclature of species uniquely found around continental Southern Africa. That changed after, within 1892, Baker contributed a number one mintage accepted into the genus from either Madagascar. A degree of speciation then turned to Madagascar, where a count of metal money far exceeds people on the mainland.

Around 1907, Costantin and Bois constructed the number one monograph, of Pachypodium, in which it enumerated Xvii mintage, in which x were from either Madagascar and seven were from either continental southern Africa.

Natural history
No fossil records of Pachypodium known. However certawithin conclusions may be drawn from either a geology of the landscape in Madagascar when to the retiring natural history of Pachypodium.