Doum palm

The quest for imitations of ivory have led to the use of vegetable ivory, the hard white nuts produced by various tropical trees. The most common of these are the doum palm (Hyphanae thebaica) and the tagua Phytelephas macro-carpa). These nuts have a brown fibrous rind, but the meat inside is homogeneous white or yellowish white. Softer than ivory, these nuts are easy to carve, and are popular for making small items such as netsuke, buttons, beads, and jewelry. 

The form and structure of the nut varies with each species. The doum palm produces fruits the size of small oranges, that each hold one kernel (nut), while the tagua produces fruits the size of human heads, that contain multiple kernels. Both types of kernel are about the size of a chicken s egg. The tagua is the nut most used today. 

A D-mannan was obtained from the kernel of the African doum palm (Hyphaene thebaica).119 a-D-Mannans having glucose as aminor componenthave been isolated from the lichen Tornabenia intricata.120... 

Preparation. Shavings obtained from the ivory nut (Phytelephas macrocarpa) are considered the best source for the preparation of 26. Alternatively, shavings obtained from doum-palm kernel may be used.125 The shavings are hydrolyzed with mineral acid, and, by fractionation with alcohols D-mannose is separated from other substances and crystallized directly from the alcoholic solution. 

M. A. E. Sallam, Preparation of D-mannose from doum-palm kernels, Carbohydr. Res., 53 (1977) 134-135. 

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