Dendrobium cumulatum Lindl. 1855 SECTION Calcarifera
Photo by Eric Hunt
Photo by Giant and the Muangsiri Website
and 
Common Name The Crowded-Inflorescence Dendrobium - In Thailand Ueang Sai Si Dok
Flower Size 1.2 to 1.6" [3 to 4 cm]
Found in Assam India, eastern Himalayas, Nepal, Bhutan, Sikkim, Myanmar, Thailand, Cambodia, Laos, Vietnam and Borneo in tropical valleys or lower montane or swamp peat forests at elevations of 300 to 1500 meters as a medium to large sized, hot to cool growing epiphyte with pendulous, basally narrowed and laterally flattened pseudobulbs carrying 4 to 6, deciduous, 3 to 4" leaves that blooms in the winter and summer on a 4" [10 cm] long, racemose inflorescence with vanilla scented, transparent flowers arising from lateral nodes of leafed and leafless canes.
CAUTION There are 2 distinct flower forms here and I am not sure which one is correct as the references are split 50/50 between the 2 so please use with caution!!
Synonyms Callista cumulata (Lindl.) Kuntze 1891; Dendrobium eoum Ridl. 1896; Eurycaulis cumulatus (Lindl.) M.A.Clem. 2003; Pedilonum eoum (Ridl.) Rauschert 1983
References W3 Tropicos, Kew Monocot list , IPNI ; Otia Botanica Hamburgensia Rchb.f 1878; Orchids of Burma Grant 1895/1995; The Orchids of Sikkim-Himalaya Part 1 King & Pantling 1898 drawing good; Orchidaceae Monandre-Dendrobiinae Fr. Kraenzlin 1910; Orchidaceae Monandre-Dendrobiinae Fr. Kraenzlin 1910 as D eoum; AOS Bulletin Vol 27 No 3 1958 drawing ok; The Orchids of Thailand Seidenfaden & Smitinand 1960 pg 247 as D eoum; The Orchids of Thailand Seidenfaden & Smitinand 1960 pg 241 as D sanguinolentum description only, The Orchids of Thailand Seidenfaden & Smitinand 1960 drawing ok; The Orchids of Thailand Seidenfaden & Smitinand 1965 corrections drawing good; Indian Orchids: A guide to Identification and Culture Vol II Pradhan 1979 photo ok; Orchids of Arunachal Pradesh Hegde 1984 photo ok; Opera Botanica #83 Orchid Genera in Thailand XII Dendrobium Sw. Seidenfaden 1985 drawing/photo fide; Thai Orchid Species Rakpaibulsombay 1992 photo fide; The Plants of Mount Kinabalu Vol 2 Orchids Wood Beaman & Beaman 1993 drawing fide/photo not = D jiewhoei; A Checklist of the Orchids of Borneo Wood & Cribb 1994; Identification of the Orchids [Orchidaceae Juss.] Vietnam Averyanov 1994; Orchid Species Culture; Dendrobium Bakers 1996; Dendrobium and their Relatives Lavarack, Harris and Stocker 2000 photo fide to the first photo; Orchids of Sarawak Beaman, Wood, Beaman & Beaman 2001; A Field Guide to the Wild Orchids of Thailand Vaddhanaphuti 2001 photo fide to the second photo; Orchids of Bhutan Pearce & Cribb 2002; A field Guide to the Wild Orchids of Thailand Vaddhanaphuti 2005 photo fide to the 2nd photo; 100 Sikkim Himalayan Orchids Pradham 2005 photo fide; The Dendrobiums H. P. Wood 2006 photo fide to the first photo; Orchids of India A Glimpse Misra 2007; The Orchids of Mount Kinabalu Vol 1 Wood, Beaman, Lamb, Chu Lun and Beaman 2011 drawing fide; Turczaninowia 16(4):26-46 NEW AND RARE ORCHIDS (ORCHIDACEAE) IN THE FLORA OF CAMBODIA AND LAOS Averyanov 2013 ; Dendrobium of Borneo Wood 2014 photo fide; AOS Bulletin Vol 86 # 11 2017 photo fide;
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