Senecio johnstonii

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Dendrosenecio johnstonii
Scientific classification
Kingdom: Plantae
Division: Magnoliophyta
Class: Magnoliopsida
Order: Asterales
Family: Asteraceae
Tribe: Senecioneae
Genus: Dendrosenecio
Species: D. johnstonii
Binomial name
Dendrosenecio johnstonii
(Oliv.) B.Nord.
Synonyms

See text.
Source:[1][2][3]

Senecio johnstonii is one of the giant groundsel endemic to the mountains in East Africa, chosen to be the type species for Dendrosenecio[3], reclassified by some to be of the genus Dendrosenecio,[3] but still a Senecio to others.[1][2] While various subspecies and varieties of Dendrosenecio johnstonii reside on many of the mountains, the actual type species is endemic to Kilimanjaro. For the purposes of these articles about Dendrosenecio and the various subspecies and varieties, Dendrosenecio johnstonii and Senecio johnstonii will be treated as if they are only found on Kilimanjaro (to solve this problem).

Recent biogeographic interpretation of the molecular phylogeny of the collected specimens of the giant groundsels suggests that about a million years ago, the first Senecio established themselves atop of Kilimanjaro. Those that survived the extreme daily conditions found at the heights of that young mountain adapted and became the species we now know as Dendrosenecio kilimanjari. As this species moved down the mountain, it adapted to the different conditions and environment found at the lower altitudes and became at least two different species, Dendrosenecio johnstonii[4] and on damper/wetter soils, Senecio cottonii which no longer exists since the reclassification of the species.


Contents

[edit] Description

Dendrosenecio johnstonii can be up to 10 meters tall, with trunk 40 centimeters (17 inches) or more in diameter with 1 to 2 centimeters of pith. Leaf nodes reproduce and branch repeatedly which can make a dense canopy of 50 to 80 branches on mature trees. Leaf surfaces are to 53 centimeters (approximately 2 foot) long, 40 centimeters wide, heart-shaped (cordate) and hairless. Inflorescense is 60 centimeters (2 feet) tall, 40 centimeters diameter with a broad pyramid of flower heads at the top, bresented horizontally. 11 to 15 ray florets up to 25 millimeters (1 inch) long and 30 to 50 disc florets.[5]

[edit] Distribution

D. johnstonii lives between the altitudes of 2,750 and 3,350 meters (9,000 and 11,000 feet) on Kilimanjaro.[5]

The following excerpts were presented as first hand accounts:

Kilimanjaro (1903)
"Ravines longer retain a somewhat richer vegetation. The last stunted Erica-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 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."[6]
Kilimanjaro (2007)
"There is no bamboo zone, nor a Hagenia-Hypericum 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), and mosses and lichens are found right up to the summit. The upland moor consists primarily of heath/scrub plants, with Erica excelsa (Erica rossii), Philippia trimera (Erica trimera), Adenocarpus mannii, Protea kilimandscharica (Protea caffra), Stoebe kilimandscharica (Seriphium kilimandscharicum), Myrica meyeri-johannis (Morella salicifolia), and Myrsine africana. Grasses are abundant in places, and Cyperaceae 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 composed of Agrostis producta, Festuca convoluta (Poa kilimanjarica), Koeleria gracilis (Koeleria capensis), Deschampsia sp., Exotheca abyssinica and Andropogon amethystinus, with scattered bushes of Adenocarpus mannii, Kotschya recurvifolia and Myrica meyeri-johannis (Morella salicifolia). Various species of Helichrysum 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 bogs is associated with another conspicuous plant, growing up to 10m tall, the endemic giant lobelia Lobelia deckenii. Below the tree line, the park includes six corridors through the forest to the mountain foot."[7]

[edit] Infraspecific name synonymy

The names for the giant groundsels have become somewhat confusing, most of the confusion being associated with this name:

  • Dendrosenecio elgonensis (T.C.E.Fr.) E.B.Knox subsp. barbatipes (Hedberg) E.B.Knox
    • Dendrosenecio johnstonii (Oliv.) B.Nord. subsp. barbatipes (Hedberg) B.Nord.
    • Senecio barbatipes Hedberg
    • Senecio gardneri Cotton - non C.B.Clarke-- nom.illegit. (ill.)
    • Senecio gardneri Cotton var. ligulatus Cotton & Blakelock
    • Senecio johnstonii Oliv. subsp. barbatipes (Hedberg) Mabb.
    • Senecio johnstonii Oliv. var. ligulatus (Cotton & Blakelock) C.Jeffrey[8]
  • Dendrosenecio adnivalis (Stapf) E.B.Knox var. adnivalis
    • Dendrosenecio johnstonii (Oliv.) B.Nord. subsp. refractisquamatus (De Wild.) B.Nord.
    • Senecio adnivalis Stapf
    • Senecio adnivalis Stapf subsp. refractisquamatus (De Wild.) Hauman
    • Senecio adnivalis Stapf var. erioneuron (Cotton) Hedberg
    • Senecio adnivalis Stapf var. intermedia Hauman
    • Senecio adnivalis Stapf var. oligochaeta Hauman
    • Senecio alticola T.C.E.Fr. var. subcalvescens Hauman
    • Senecio erioneuron Cotton
    • Senecio johnstonii Oliv. subsp. refractisquamatus (De Wild.) Mabb.
    • Senecio johnstonii Oliv. var. adnivalis (Stapf) C.Jeffrey
    • Senecio refractisquamatus De Wild. [9]
  • Dendrosenecio battiscombei (R.E.Fr. & T.C.E.Fr.) E.B.Knox
    • Dendrosenecio johnstonii (Oliv.) B.Nord. subsp. battiscombei (R.E.Fr. & T.C.E.Fr.) B.Nord.
    • Senecio aberdaricus R.E.Fr. & T.C.E.Fr.
    • Senecio battiscombei R.E.Fr. & T.C.E.Fr.
    • Senecio johnstonii Oliv. var. battiscombei (R.E.Fr. & T.C.E.Fr.) Mabb.[10]
  • Dendrosenecio cheranganiensis (Cotton & Blakelock) E.B.Knox subsp. cheranganiensis
    • Dendrosenecio cheranganiensis (Cotton & Blakelock) E.B.Knox subsp. cheranganiensis (2005).
    • Dendrosenecio johnstonii (Oliv.) B.Nord. subsp. cheranganiensis (Cotton & Blakelock) B.Nord.
    • Senecio cheranganiensis Cotton & Blakelock
    • Senecio johnstonii Oliv. subsp. cheranganiensis (Cotton & Blakelock) Mabb.[11]
  • Dendrosenecio elgonensis (T.C.E.Fr.) E.B.Knox subsp. elgonensis
    • Dendrosenecio johnstonii (Oliv.) B.Nord. subsp. elgonensis (T.C.E.Fr.) B.Nord.
    • Senecio amblyphyllus Cotton
    • Senecio elgonensis T.C.E.Fr.
    • Senecio johnstonii Oliv. var. elgonensis (T.C.E.Fr.) Mabb.[12]
  • Dendrosenecio adnivalis (Stapf) E.B.Knox subsp. friesiorum (Mildbr.) E.B.Knox
    • Dendrosenecio johnstonii (Oliv.) B.Nord. var. friesiorum (Mildbr.) B.Nord.
    • Senecio albescens De Wild.
    • Senecio friesiorum Mildbr.
    • Senecio hypoleucus Muschl.
    • Senecio johnstonii Oliv. var. friesiorum (Mildbr.) Mabb.[13]
  • Senecio johnstonii Oliv. var. dalei (Cotton & Blakelock) C.Jeffrey
    • Senecio dalei Cotton & Blakelock[14]
  • Dendrosenecio meruensis (Cotton & Blakelock) E.B.Knox
    • Senecio johnstonii Oliv. var. meruensis (Cotton & Blakelock) C.Jeffrey
    • Senecio meruensis Cotton & Blakelock[15]
  • Dendrosenecio erici-rosenii (R.E.Fr. & T.C.E.Fr.) E.B.Knox subsp. erici-rosenii
    • Senecio erici-rosenii R.E.Fr. & T.C.E.Fr.
    • Senecio johnstonii Oliv. var. erici-rosenii (R.E.Fr. & T.C.E.Fr.) C.Jeffrey
    • Senecio kahuzicus Humb.
    • Senecio longeligulatus De Wild.[16]
  • Dendrosenecio kilimanjari (Mildbr.) E.B.Knox subsp. cottonii (Hutch. & G.Taylor) E.B.Knox
    • Dendrosenecio johnstonii (Oliv.) B.Nord. subsp. cottonii (Hutch. & G.Taylor) B.Nord.
    • Senecio cottonii Hutch. & G.Taylor
    • Senecio johnstonii Oliv. subsp. cottonii (Hutch. & G.Taylor) Mabb.
    • Senecio johnstonii Oliv. var. cottonii (Hutch. & G.Taylor) C.Jeffrey[17]
  • Dendrosenecio kilimanjari (Mildbr.) E.B.Knox subsp. kilimanjari
    • Senecio johnstonii Oliv. var. kilimanjari (Mildbr.) C.Jeffrey
    • Senecio kilimanjari Mildbr.[18]
  • Dendrosenecio erici-rosenii (R.E.Fr. & T.C.E.Fr.) E.B.Knox subsp. alticola (Mildbr.) E.B.Knox
    • Senecio adnivalis Stapf var. alticola (T.C.E.Fr.) Hedberg
    • Senecio adnivalis Stapf var. intermedia Hauman
    • Senecio alticola T.C.E.Fr. var. subcalvescens Hauman
    • Senecio johnstonii Oliv. var. alticola (T.C.E.Fr.) C.Jeffrey
    • Senecio refractisquamatus De Wild. var. intermedia (Hauman) Robyns [19]


[edit] References

  1. ^ a b Dendrosenecio johnstonii (Oliv.) B.Nord. record n° 183008 (HTML). African Plants Database. South African National Biodiversity Institute, the Conservatoire et Jardin botaniques de la Ville de Genève and Tela Botanica. Retrieved on 2008-05-13.
  2. ^ a b Senecio johnstonii Oliv. record n° 176140 (HTML). African Plants Database. South African National Biodiversity Institute, the Conservatoire et Jardin botaniques de la Ville de Genève and Tela Botanica. Retrieved on 2008-05-13.
  3. ^ a b c Index Nominum Genericorum database (HTML). International Code of Botanical Nomenclature. Smithsonian Institution (1978). Retrieved on 2008-05-04.
  4. ^ Knox, Eric B. (2004). "Adaptive radiation of African montane plants", in Ulf Dieckmann: Adaptive Speciation (HTML), Cambridge University Press, 476 pages. ISBN 0521828422. Retrieved on 2008-03-29. 
  5. ^ a b Aluka. Entry for Dendrosenecio johnstonii (Oliv.) B.Nord. (HTML). African Plants. Ithaka Harbors, Inc. DOI:10.5555/AL.AP.FLORA.FTEA006283. Retrieved on 2008-05-14.
  6. ^ Schimper, Andreas Franz Wilhelm; William Rogers Fisher, Percy Groom, Isaac Bayley Balfour (1903). "Mountain Regions in the Tropics", in Translation of Pflanzen-geographie auf physiologischer Grundlage by William Rogers Fisher: Plant-geography Upon a Physiological Basis (HTML), Clarendon Press. Retrieved on 2008-05-08. 
  7. ^ World Conservation Monitoring Centre; Langdon D. Clough (2007-10-03). Kilimanjaro National Park, Tanzania (HTML). Encyclopedia of Earth. United Nations Environment Programme. Retrieved on 2008-03-27.
  8. ^ Dendrosenecio elgonensis (T.C.E.Fr.) E.B.Knox subsp. barbatipes (Hedberg) E.B.Knox record n° 105256 (HTML). African Plants Database. South African National Biodiversity Institute, the Conservatoire et Jardin botaniques de la Ville de Genève and Tela Botanica. Retrieved on 2008-05-13.
  9. ^ Dendrosenecio adnivalis (Stapf) E.B.Knox var. adnivalis record n° 105247 (HTML). African Plants Database. South African National Biodiversity Institute, the Conservatoire et Jardin botaniques de la Ville de Genève and Tela Botanica. Retrieved on 2008-05-13.
  10. ^ Dendrosenecio battiscombei (R.E.Fr. & T.C.E.Fr.) E.B.Knox record n° 105250 (HTML). African Plants Database. South African National Biodiversity Institute, the Conservatoire et Jardin botaniques de la Ville de Genève and Tela Botanica. Retrieved on 2008-05-13.
  11. ^ Dendrosenecio cheranganiensis (Cotton & Blakelock) E.B.Knox record n° 105254 (HTML). African Plants Database. South African National Biodiversity Institute, the Conservatoire et Jardin botaniques de la Ville de Genève and Tela Botanica. Retrieved on 2008-05-13.
  12. ^ Dendrosenecio elgonensis (T.C.E.Fr.) E.B.Knox subsp. elgonensis record n° 105257 (HTML). African Plants Database. South African National Biodiversity Institute, the Conservatoire et Jardin botaniques de la Ville de Genève and Tela Botanica. Retrieved on 2008-05-13.
  13. ^ Dendrosenecio adnivalis (Stapf) E.B.Knox subsp. friesiorum (Mildbr.) E.B.Knox record n° 105249 (HTML). African Plants Database. South African National Biodiversity Institute, the Conservatoire et Jardin botaniques de la Ville de Genève and Tela Botanica. Retrieved on 2008-05-13.
  14. ^ Senecio johnstonii Oliv. var. dalei (Cotton & Blakelock) C.Jeffrey record n° 98676 (HTML). African Plants Database. South African National Biodiversity Institute, the Conservatoire et Jardin botaniques de la Ville de Genève and Tela Botanica. Retrieved on 2008-05-13.
  15. ^ Dendrosenecio meruensis (Cotton & Blakelock) E.B.Knox n°105272 (HTML). African Plants Database. South African National Biodiversity Institute, the Conservatoire et Jardin botaniques de la Ville de Genève and Tela Botanica. Retrieved on 2008-05-13.
  16. ^ Dendrosenecio erici-rosenii (R.E.Fr. & T.C.E.Fr.) E.B.Knox subsp. erici-rosenii record n° 105259 (HTML). African Plants Database. South African National Biodiversity Institute, the Conservatoire et Jardin botaniques de la Ville de Genève and Tela Botanica. Retrieved on 2008-05-13.
  17. ^ Dendrosenecio kilimanjari (Mildbr.) E.B.Knox subsp. cottonii (Hutch. & G.Taylor) E.B.Knox record n° 105270 (HTML). African Plants Database. South African National Biodiversity Institute, the Conservatoire et Jardin botaniques de la Ville de Genève and Tela Botanica. Retrieved on 2008-05-13.
  18. ^ Dendrosenecio kilimanjari (Mildbr.) E.B.Knox subsp. kilimanjari (Hutch. & G.Taylor) E.B.Knox record n° 105271 (HTML). African Plants Database. South African National Biodiversity Institute, the Conservatoire et Jardin botaniques de la Ville de Genève and Tela Botanica. Retrieved on 2008-05-13.
  19. ^ Dendrosenecio erici-rosenii (R.E.Fr. & T.C.E.Fr.) E.B.Knox subsp. alticola (Mildbr.) E.B.Knox record n° 105258 (HTML). African Plants Database. South African National Biodiversity Institute, the Conservatoire et Jardin botaniques de la Ville de Genève and Tela Botanica. Retrieved on 2008-05-13.

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