^ Qg BIOCHEMICAL SYSTEMATICS 



y-Methyleneglutamine was reported only in the two genera, 

 Tulipa and Erythronium but was present in all species of Tulipa 



examined. 



y-Hydroxy-y-methylglutamic acid was found as traces in six 

 genera including Tulipa (many species), Erythronium, Littonia, 

 Lilium, Calochortus, and Puschkinia. y-Hydroxyglutamic acid was 

 found in only two genera: Hemerocallis and Gasteria. 



The association of these unusual amino acids among certain 

 related genera is of taxonomic significance. It is especially interesting 

 that Calochortus contains two of the acids since Ownbey (1940) has 

 stated that "the relationship of the genus [Calochortus] as a whole, 

 although remote, is probably rather with the genus Tulipa.'' Recently, 

 Buxbaum (1958) established this genus as the single member of the 

 new tribe, Calochorteae. However, Hutchinson (1959) retains Calo- 

 chortus and related genera {Erythronium, Fritillaria, Tulipa, Lloydia, 

 Gagea, Notholirion, Lilium, Nomocharis, and Giraldiella) in the 

 more inclusive tribe Tulipeae. Using the amino acid criteria alone it 

 would appear that Ownbey's comments are especially significant, and 

 intensive chemical studies should contribute significant data to estab- 

 lish the phylogenetic affinities of the genera. 



Two other acids, not derivatives of glutamic acid and hence 

 not included in the natural group above, had a rather restricted dis- 

 tribution within the Liliaceae. One of these, hydroxyproline, was de- 

 tected only in Dracaena (which is now placed in the family Agava- 

 ceae by many workers, Hutchinson, 1959). Another, azetidine-2- 

 carboxylic acid, has already been discussed. Finally, pipecohc acid, 

 the next higher analog of proline, appeared in nine genera, including 

 Hosta, Haworthia, Fritillaria, Chionodoxa, Hyacinthus, Muscari, 

 Smilacina, Convalleria, and Maianthemum. 



CH2CH2CH2CH2CHCOOH 



N ' 



H 



pipecolic acid 



These distinctive glutamic acid derivatives seem to occur 

 sporadically among widely separated taxa (for example, peanut, ferns, 

 phlox). Fowden and Steward state that this distribution implies the 

 genetic factors responsible do not operate at the generic or specific 

 level; that is, "in short, the accumulation of any of these compounds 

 may be determined by relatively few of the genes that characterize 

 the organism." In other words, since the compounds are not re- 

 stricted to a genus or species, their synthesis could not therefore de- 

 pend upon the specific association of a large species-dehmiting gene 



