Rheum nobile Hook. f. & Thomson, Ill. Himal. Pl. , pl. 19 1855. ;



Rheum nobile, the Noble rhubarb or Sikkim rhubarb or पदमचाल, is a giant herbaceous plant native to the Himalaya, from northeastern Afghanistan, east through northern Pakistan and India, Nepal, Sikkim (in India), Bhutan, and Tibet to Myanmar, occurring in the alpine zone at 4000–4800 m altitude.[1]

It is an extraordinary species of rhubarb (genus Rheum). At 1–2 m tall, R. nobile towers above all the shrubs and low herbs in its habitat, and it is visible across valleys a mile away.[2]
R. nobile is often called a glasshouse plant because of its outer curtain of translucent bracts which pass visible light, creating a greenhouse effect, while blocking ultraviolet radiation. These are important defenses against the increased UV-B exposure and extreme cold in its high altitude range.[3]
An individual R. nobile is a conical tower of delicate, straw-coloured, shining, translucent, regularly overlapping bracts; the higher ones have pink edges. Large, glossy, green radicle leaves, with red petioles and nerves, form a broad base to the plant. Turning up the bracts reveals membranous, fragile, pink stipules. Within these are short branched panicles of diminutive green flowers.[4]
The root is often 1–2 m (3.3–6.6 ft) long and as thick as an arm, and bright yellow inside. The stems are pleasantly acidic, and they are consumed by the local people, who call the plant Chuka. The hollow of the stem contains a good deal of limpid water. After flowering, the stem lengthens and the bracts separate one from another, turning a coarse red-brown. As the fruit ripens, the bracts fall away, leaving a ragged-looking stem covered with panicles of deep brown pendulous fruits. As Hooker put their appearance: “In the winter, these naked black stems, projecting from the beetling cliffs, or towering above the snow, are in dismal keeping with the surrounding desolation of that season.”.[4]

(From Wikipedia on 18.1.17)


 

Fwd: Rheum nobile – new to efi : 1 post by 1 author.

Having just posted links to 2 images of Pleurospermum amabile taken by Roger Nix it seems efficient also to post an image taken by him of Rheum nobile, as this is also new to eFI.
According to ‘Flowers of the Himalaya’ R.nobile is known from Eastern Nepal to SE Tibet on open slopes @ 3600-4500m.  Another very striking and distinctive-looking plant, unlikely to be mistaken for anything else – which makes a pleasant change!
The stout stems bear a conical spike of large pale cream-coloured, rounded and bladder-like, drooping and overlapping bracts which conceal the short flower-clusters.
I will take a close look at the postings of other Rheums on eFI at some point.
‘Flora of Bhutan’ says rocky hillsides @ 4250-4600m.


 

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