''Dendrosenecio johnstonii'', formerly ''Senecio johnstonii'', is a species of giant groundsel found in the middle altitudes of

Mount Kilimanjaro Mount Kilimanjaro () is a dormant volcano in Tanzania. It has three volcanic cones: Kibo, Mawenzi, and Shira. It is the highest mountain in Africa and the highest free-standing mountain above sea level in the world: above sea level and ab ...

Africa Africa is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area ...

. A recent botanical reclassification split off some species formerly in ''Senecio'', putting the giant groundsels in the new genus ''Dendrosenecio''. It also redefined the former species ''Senecio cottonii'', as a subspecies of ''Dendrosenecio johnstonii''. Both genera are in the family ''

Asteraceae The family Asteraceae, alternatively Compositae, consists of over 32,000 known species of flowering plants in over 1,900 genera within the order Asterales. Commonly referred to as the aster, daisy, composite, or sunflower family, Compositae w ...

''. The giant grounsels of the genus ''Dendrosenecio'' evolved, about a million years ago, from a ''Senecio'' that established itself on Mount Kilimanjaro, with those that survived adapting into ''

Dendrosenecio kilimanjari ''Dendrosenecio kilimanjari'' is a giant groundsel found on Mount Kilimanjaro in Africa, below . Taxonomy It was originally known as ''Senecio kilimanjari'', but a recent botanical reclassification split off some species formerly in ''Seneci ...

''. As it moved down the mountain, the

adaptation In biology, adaptation has three related meanings. Firstly, it is the dynamic evolutionary process of natural selection that fits organisms to their environment, enhancing their evolutionary fitness. Secondly, it is a state reached by the po ...

s necessary for the new environment created the new species, ''Dendrosenecio johnstonii''. Various subspecies are found on other mountains.

Description

''Dendrosenecio johnstonii'' can be up to 10 meters tall, and grow to 40 centimeters (17 inches) or more in diameter. The centre of the stem, at full size, contains 1 to 2 centimeters of

pith Pith, or medulla, is a tissue in the stem Stem or STEM may refer to: Plant structures * Plant stem, a plant's aboveground axis, made of vascular tissue, off which leaves and flowers hang * Stipe (botany), a stalk to support some other ...

. It branches repeatedly, forming a dense canopy with 50 to 80 branches when mature. The leaves are hairless, heart-shaped (cordate) and large, 53 centimetres (approximately 2 feet) long by 40 centimetres (16 inches) wide. The flower shoot is a tall, broad cone, 60 centimetres (about 2 feet) tall, and 40 centimetres (16 inches) wide, with the

flower head A pseudanthium (Greek for "false flower"; ) is an inflorescence that resembles a flower. The word is sometimes used for other structures that are neither a true flower nor a true inflorescence. Examples of pseudanthia include flower heads, compos ...

s horizontal. Each floret is about 25 millimetres (one inch) long, and the compound flower is made up of 11 to 15 of the petal-like ray florets, with thirty to fifty "disc" florets in the centre.

Distribution

''D. johnstonii'' lives between the altitudes of 2,750 and 3,350 meters (9,000 and 11,000 feet) on Kilimanjaro. The following excerpts were presented as first hand accounts: ;

Kilimanjaro Mount Kilimanjaro () is a dormant volcano in Tanzania. It has three volcanic cones: Kibo, Mawenzi, and Shira. It is the highest mountain in Africa and the highest free-standing mountain above sea level in the world: above sea level and ab ...

(1903): "Ravines longer retain a somewhat richer vegetation. The last stunted ''

Erica Erica or ERICA may refer to: * Erica (given name) * ''Erica'' (plant), a flowering plant genus * Erica (chatbot), a service of Bank of America * ''Erica'' (video game), a 2019 FMV video game * ''Erica'' (spider), a jumping spider genus * Eric ...

''-trees disappear from them at 2,900 meters; and are replaced by a new characteristic plant of very peculiar habit, the arboreous ''Senecio johnstonii'', with a spongy, simple or forked stem, the top of which bears a rosette of leaves as long as one's arm, and a dense inflorescence a meter in length." :"''Senecio johnstonii'' bears the least resemblance to the alpine habit in this region. It is remarkable, however, that plants of similar habit are also found on tropical high mountains elsewhere. For the Vellozieae of Brazil are similar, and so to some extent are species of

Espeletia ''Espeletia'', commonly known as 'frailejones' ("big monks"), is a genus of perennial subshrubs, in the family Asteraceae. The genus, which is native mainly to Colombia, Venezuela and Ecuador, was first formally described in 1808. The genus was n ...

in the Cordilleras of Venezuela.... In other respects the impress of the alpine climate is most clearly stamped on the vegetation, especially in the higher part of the region, with its dwarf plants. Protective measures against transpiration are everywhere strongly developed, in particular dense coatings of woolly hairs are frequent." ;

(2007): "There is no bamboo zone, nor a ''

Hagenia ''Hagenia'' is a monotypic genus of flowering plant with the sole species ''Hagenia abyssinica'', native to the high-elevation Afromontane regions of central and eastern Africa. It also has a disjunct distribution in the high mountains of East A ...

''-''

Hypericum ''Hypericum'' is a genus of flowering plants in the family Hypericaceae (formerly considered a subfamily of Clusiaceae). The genus has a nearly worldwide distribution, missing only from tropical lowlands, deserts and polar regions. Many ''Hype ...

'' zone. Above about 4,600 meters, very few plants are able to survive the severe conditions, although specimens of '' Helichrysum newii'' have been recorded as high as 5,760 meters (close to a

fumarole A fumarole (or fumerole) is a vent in the surface of the Earth or other rocky planet from which hot volcanic gases and vapors are emitted, without any accompanying liquids or solids. Fumaroles are characteristic of the late stages of volcani ...

), and

moss Mosses are small, non-vascular flowerless plants in the taxonomic division Bryophyta (, ) '' sensu stricto''. Bryophyta (''sensu lato'', Schimp. 1879) may also refer to the parent group bryophytes, which comprise liverworts, mosses, and hor ...

es and

lichen A lichen ( , ) is a composite organism that arises from algae or cyanobacteria living among filaments of multiple fungi species in a mutualistic relationship.moor Moor or Moors may refer to: Nature and ecology * Moorland, a habitat characterized by low-growing vegetation and acidic soils. Ethnic and religious groups * Moors, Muslim inhabitants of the Maghreb, Iberian Peninsula, Sicily, and Malta during ...

consists primarily of

heath A heath () is a shrubland habitat found mainly on free-draining infertile, acidic soils and characterised by open, low-growing woody vegetation. Moorland is generally related to high-ground heaths with—especially in Great Britain—a cooler ...

/ scrub plants, with ''Erica excelsa'' ('' Erica rossii''), ''Philippia trimera'' (''

Erica trimera ''Erica trimera'' is a species of flowering plant. It is a shrub or tree which grows in the mountains of eastern and central Africa. Description ''Erica trimera'' is an evergreen shrub or tree which grows from .4 to 12 meters in height, with a ...

''), ''

Adenocarpus mannii ''Adenocarpus'' is a genus of flowering plants in the family Fabaceae. It belongs to the subfamily Faboideae. The plants are broom-like shrubs with bright yellow flowers. The genus is native to Macaronesia, Portugal and southern Spain, and th ...

'', ''Protea kilimandscharica'' (''

Protea caffra ''Protea caffra'' (sometimes called the common protea), native to South Africa, is a small tree or shrub which occurs in open or wooded grassland, usually on rocky ridges. Its leaves are leathery and hairless. The flower head is solitary or in cl ...

''), ''Stoebe kilimandscharica'' (''

Seriphium kilimandscharicum ''Stoebe'' is a genus of African plants in the tribe Gnaphalieae within the family Asteraceae. ; Species ; formerly included A few dozen species now regarded as members of other genera: '' Dicerothamnus Dolichothrix Disparago Gongyloglossa He ...

''), ''Myrica meyeri-johannis'' ('' Morella salicifolia''), and ''

Myrsine africana ''Myrsine africana'', also called Cape myrtle, African boxwood or thakisa, is a species of shrub in the family Primulaceae. It is indigenous to Southern and Eastern Africa, the Azores, the Arabian Peninsula, South Asia and East Asia. Descrip ...

''. Grasses are abundant in places, and ''

Cyperaceae The Cyperaceae are a family of graminoid (grass-like), monocotyledonous flowering plants known as sedges. The family is large, with some 5,500 known species described in about 90 genera, the largest being the "true sedges" genus ''Carex'' w ...

'' form the dominant ground cover in wet hollows. On flatter areas between the upland moor and the forest edge are areas of moorland or upland

grassland A grassland is an area where the vegetation is dominated by grasses (Poaceae). However, sedge (Cyperaceae) and rush (Juncaceae) can also be found along with variable proportions of legumes, like clover, and other herbs. Grasslands occur natur ...

composed of ''

Agrostis producta ''Agrostis'' (bent or bentgrass) is a large and very nearly cosmopolitan genus of plants in the grass family, found in nearly all the countries in the world. It has been bred as a GMO creeping bent grass. Species * ''Agrostis aequivalvi'' (Ar ...

'', ''Festuca convoluta'' ('' Poa kilimanjarica''), ''Koeleria gracilis'' (''

Koeleria capensis ''Koeleria'' is a common and widespread genus of plants in the grass family, found on all continents except Antarctica and on various oceanic islands. It includes species known generally as Junegrasses. The genus was named after German botanis ...

''), ''

Deschampsia ''Deschampsia'' is a genus of plants in the grass family, commonly known as hair grass or tussock grass. The genus is widespread across many countries.

'' sp., '' Exotheca abyssinica'' and ''

Andropogon amethystinus ''Andropogon'' (common names: beard grass, bluestem grass, broomsedge) is a widespread genus of plants in the grass family, native to much of Asia, Africa, and the Americas, as well as southern Europe and various oceanic islands. Over 100 specie ...

'', with scattered bushes of ''

'', ''

Kotschya recurvifolia ''Kotschya'' is a genus of legumes in the family Fabaceae, and was recently assigned to the informal monophyletic ''Dalbergia'' clade of the Dalbergieae. It contains the following species: * '' Kotschya aeschynomenoides'' (Baker) Dewit & P.A. ...

'' and ''Myrica meyeri-johannis'' ('' Morella salicifolia''). Various species of ''

Helichrysum The genus ''Helichrysum'' consists of an estimated 600 species of flowering plants in the sunflower family (Asteraceae). The type species is ''Helichrysum orientale''. They often go by the names everlasting, immortelle, and strawflower. The name ...

'' are found in the grasslands and in the upland moor. Two distinct forms of giant groundsel occur on the upper mountain: ''Senecio johnstonii cottonii'', endemic to the mountain and only occurring above 3600 meters , and ''S.johnstonii johnstonii'' which occurs between 2,450 meters and 4,000 meters, and shows two distinct forms. At all altitudes ''Senecio'' favours the damper and more sheltered locations, and in the alpine

bog A bog or bogland is a wetland that accumulates peat as a deposit of dead plant materials often mosses, typically sphagnum moss. It is one of the four main types of wetlands. Other names for bogs include mire, mosses, quagmire, and muskeg; a ...

s is associated with another conspicuous plant, growing up to 10m tall, the endemic giant lobelia ''

Lobelia deckenii ''Lobelia deckenii'' is a species of flowering plant in the family Campanulaceae. It is a giant lobelia endemic to the mountains of Tanzania. It is listed as a threatened plant of the forests of Cherangani hills, Kenya. It grows in moist areas, ...

''. Below the tree line, the park includes six corridors through the forest to the mountain foot."

References

External links

* * {{Taxonbar, from=Q5256846 johnstonii Endemic flora of Kenya Mount Kilimanjaro Afromontane flora