1 38 BIOCHEMICAL SYSTEMATICS 



inulin. Related, but different fructose polysaccharides are apparently 

 found in some grasses. According to Hegnauer (1958) inulin has been 

 found in the family Boraginaceae, and Bacon (1959) found inulin in 

 species of the Campanulaceae. Hegnauer suggests a further study of the 

 distribution of fructosans in the plant kingdom, and Bacon infers from 

 the presence of inulin in the Campanulaceae a close evolutionary con- 

 nection between the family and the Compositae. A comprehensive 

 survey of the Compositae for inulin would be valuable. Sporadic 

 occurrences of inulin in two families is not necessarily indicative of 

 a close phylogenetic relationship between the families. 



Heptoses have been known to occur for many years, but it 

 was probably Calvin's work on the dark reactions of photosynthesis 

 that led to recognition of the biological role of certain seven-carbon 

 sugars. Mannoketoheptose is found as a free sugar in the avocado 

 pear. Free sedoheptulose was first reported from Sedum spectabile by 

 LaForge and Hudson (1917). Subsequently, the presence of free 

 sedoheptulose has been associated with the family Crassulaceae, and 

 originally the sugar was considered to occur in the free state only in 

 this family. For example, Nordal and Klevstrand (1951a; 1951b) 

 found free sedoheptulose in all five sub-families of the Crassulaceae. 

 However, Nordal and Oiseth (1951, 1952) examined Primula elatior, 

 P. vulgaris and P. veris (Primulaceae) and found sedoheptulose and 

 probably mannoheptulose. These were the first reports of sedohep- 

 tulose outside of the family Crassulaceae. The search for sedohep- 

 tulose in P. elatior was prompted by the identification of the seven- 

 carbon sugar-alcohol, volemitol, from the species. Nordal and Oiseth 

 reported the detection of sedoheptulose in several species of Saxifraga- 

 ceae; Chrysosplenium alternifolium, Parnassia palustris, and several 

 species of Saxifraga were positive for sedoheptulose. Williams et al. 

 (1952) also reported heptuloses in sixteen of thirty-one plant tissues ex- 

 amined, and twenty-one of twenty-three species of trees had one or 

 more heptuloses in the leaves. Recently, Brown and Hunt (1961) 

 examined 200 species of plants representing seventy-eight families and 

 found free sedoheptulose in at least one species of each of sixteen fami- 

 lies. It was prevalent in the families Corylaceae and Oleaceae, but in 

 general no clear systematic implications outside of this observation 

 were apparent. Thus, while association of the sugar with the family 

 Crassulaceae alone is no longer valid, and this particular phytochemi- 

 cal systematic correlation is negated, perhaps in a broader framework 

 the distribution of sedoheptulose will be phylogenetically significant. 

 In view of the basic metabolic significance of phosphorylated sedohep- 

 tulose, it is not surprising to find that free sedoheptulose occurs 

 outside of a single family. 



