''Dendrosenecio johnstonii'', formerly ''Senecio johnstonii'', is a species of

giant groundsel ''Dendrosenecio'' is a genus of flowering plants in the Asteraceae, sunflower family. It is a Segregate (taxonomy), segregate of ''Senecio'', in which it forms the subgenus ''Dendrosenecio''. Its members, the giant groundsels, are native to the ...

found in the middle altitudes of

Mount Kilimanjaro Mount Kilimanjaro () is a dormant volcano in Tanzania. It is the highest mountain in Africa and the highest free-standing mountain above sea level in the world, at above sea level and above its plateau base. It is also the highest volcano i ...

Africa Africa is the world's second-largest and second-most populous continent after Asia. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 20% of Earth's land area and 6% of its total surfac ...

. 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 Asteraceae () is a large family (biology), family of flowering plants that consists of over 32,000 known species in over 1,900 genera within the Order (biology), order Asterales. The number of species in Asteraceae is rivaled only by the Orchi ...

''. 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 ''Senecio ...

''. 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 p ...

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 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 stems of vascular plants. Pith is composed of soft, spongy parenchyma cells, which in some cases can store starch. In eudicotyledons, pith is located in the center of the stem. In monocotyledons, it ex ...

. 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 wide. The flower shoot is a tall, broad cone, 60 centimetres (about 2 feet) tall, and wide, with the

flower head A pseudanthium (; : pseudanthia) 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, composite flowers ...

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 on Kilimanjaro. The following excerpts were presented as first hand accounts: ;

Kilimanjaro Mount Kilimanjaro () is a dormant volcano in Tanzania. It is the highest mountain in Africa and the highest free-standing mountain above sea level in the world, at above sea level and above its plateau base. It is also the highest volcano i ...

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

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

''-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 ...

''-''

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

'' 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 another 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 plant, non-vascular flowerless plants in the taxonomic phylum, division Bryophyta (, ) ''sensu stricto''. Bryophyta (''sensu lato'', Wilhelm Philippe Schimper, Schimp. 1879) may also refer to the parent group bryo ...

es and

lichen A lichen ( , ) is a hybrid colony (biology), colony of algae or cyanobacteria living symbiotically among hypha, filaments of multiple fungus species, along with yeasts and bacteria embedded in the cortex or "skin", in a mutualism (biology), m ...

s are found right up to the summit. The upland moor consists primarily of

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

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

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 the Mediterranean Basin and sub-Saharan Africa, b ...

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

Protea afra ''Protea afra'' (sometimes called the common protea), native to Africa, inhabiting from South Africa to Kenya, is a small tree or shrub which occurs in subtropical open or wooded grassland, usually on rocky ridges. Its leaves are leathery and ha ...

''), ''Stoebe kilimandscharica'' ('' Seriphium kilimandscharicum''), ''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. Descripti ...

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

Cyperaceae The Cyperaceae () are a family of graminoid (grass-like), monocotyledonous flowering plants known as wikt:sedge, sedges. The family (biology), family is large; botanists have species description, described some 5,500 known species in about 90 ...

'' 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 dominance (ecology), dominated by grasses (Poaceae). However, sedge (Cyperaceae) and rush (Juncaceae) can also be found along with variable proportions of legumes such as clover, and other Herbaceo ...

composed of '' Agrostis producta'', ''Festuca convoluta'' ('' Poa kilimanjarica''), ''Koeleria gracilis'' (''

Koeleria capensis ''Koeleria'' is a common and widespread genus of plants in the Poaceae, 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 ...

''), ''

Deschampsia ''Deschampsia'' is a genus of plants in the grass family Poaceae, commonly known as hair grass or tussock grass. The genus is widespread across many countries.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. It includes 30 species native to sub-Saharan Africa. The genus was recently assigned to the informal monophyletic ''Dalbergia'' clade of the Dalbergieae. It contains the following species ...

'' 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 na ...

'' 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 musk ...

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