Plant families, systematics

In good agreement with the order of the systematic taxa, the next level of similarity revealed by HCA is that of plant families, as illustrated by the examples of the Birch and of the Soapberry families (Betulaceae and Sapin-daceae). Silver birch (genus Betula) and Hophornbeam (genus Ostrya) are members of the Birch family (Betulaceae), and their spectra form one of the three main data clusters. Sycamore Maple, Norway Maple and Horse-chestnut are all members of the Soapberry family (Sapindaceae), and are also contained in one group. 

Besides of Poaceae, benzoxazinoid acetal glucosides have been isolated from various species of the Acanthaceae, Ranunculaceae, and Scrophulariaceae as well. In most cases reported the discovery of benzoxazinoids was made by chance, i.e. a systematic search for them among other species of the families mentioned has not been undertaken nor has such a search been done within other plant families. Therefore, it seems most likely, that benzoxazinoids will be constituents of other wild plants, too, which are not at all as deeply investigated as agriculturally used ones. One reason for this assumption is the circumstance that the benzoxazinoids protecting effect especially for a young plant should be a favouring selection criterion in the evolution of any plant equipped with this system. 

The Umbelliferae or Apiaceae is one of the best known families of flowering plants, because of its characteristic inflorescences, fruits and the distinctive chemistry reflected in the odor, flavor and even toxicity of many of its members. The Umbelliferae seems to be the first flowering plant family to be recognized as such by botanists in around the 16th century, although only the temperate Old World species were known by then. It was also the first group of plants to be the subject of a systematic study published by Robert Morison in 1672 [15]. 

On studying the plant family Papaveraceae for the presence of alkaloids, there were isolated numerous bases whose constitution has not been elucidated and whose classification has not been carried out. It is also difficult to look for these compounds in the pertinent literature because frequently even reference journals do not record them. Boit (81) was the first to summarize them systematically in his monograph. Since then many bases have been identified and others added. In Table XXV an attempt has been made to list the thus far undetermined bases of the plant family Papaveraceae. Their identification is often difficult because especially in older literature neither the optical rotation, the IR spectra, nor the color reactions with concentrated sulfuric acid or other reagents are mentioned. 

The ease of detection of the conjugated dialkyne chromophore (at 250-350 nm) has resulted in systematic screening of plant families for alkynes on a considerable scale. The target compounds have been found in all plant organs but largely reside in the root ca 85%... 

Systematic fractionation of cytotoxic extracts of several species in the plant family Compositae has afforded a number of new sesquiterpene lactones with cytotoxic activity, some of which possess antineoplastic activity [181-188]. Elephantopin (XLllla) and elephantin (XLIIIb), which have been isolated from Elephantopus elatus, have been found to inhibit significantly W 256 at... 

AGO isozymes are encoded by multigene families in various plant species. In the systematic hierarchy, the occurrence of AGO was noted for the first time in Gnetaceae and Ephedraceae belonging to the gymnosperms. ... 

The classification of plants is primarily based on the similarities and differences that are displayed by their morphological and anatomical characteristics. In some instances this does not suffice since the morphological differences may not be genetically defined but have been caused by local bio-climatic factors. Nevertheless is apparent that secondary metabolites can contribute to the taxonomy of plants and their systematic evolution. There are many examples of cases where the morphological features are not clear and secondary metabolites serve to clarify the morphological classification (e.g. classification of the tribes of the family Asteraceae). It has also been proved to be significant to use all the secondary metabolites for the above purpose and not only one of their chemical groups [4]. 

Ehrendorfer, F. (1976) Closing remarks systematics and evolution of centrospermous families. Plant Syst. EvoL, 126, 99-106. 

Pig. 5. Publications in plant systematics. "Regional" are publication on areas like Europe, tropical Asia. Australia, "bocal" means a coverage of e.g. the Netherlands, Java, i< ifornia. Main groups are Algae, Mosses, Vascular plants, Angiosperms, etc. Small groups are orders, families, genera. Transitions between the types of publication are not sharp. 

Taxane alkaloids have a very limited distribution within the plant kingdom, and occur only in two genera of the yew family (Taxus and Austrotaxus). The genus Austrotaxus is monotypic (A. spicata Compt), but contusion exists on the systematics of the genus Taxus, especially as regards the taxonomic status of certain Asian yews. Reference will be given here to the Krttssmann classification (Table 1) [28]. 

Table 1 summarizes the alkaloid producing species found in Malaysia. The plants are listed systematically under family, genus and species. The alkaloids were detected by the Mayer or Dragendorff reagents or by TLC of an alkaloidal extract followed by detection with the Dragendorff reagent. The test results are cited as strong (s), medium (m), weak (w) or just (+) in cases where a positive result was obtained but no attempt was made to estimate the relative amount. The plant parts examined are abbreviated as follows L (leaves), B (bark), S (stem), Wd (wood), Sd (seed), F (fruit), FI (flowers), R (root) and W (whole plant). It is evident from examination of these results as well as from the subsequent chemical studies that have followed that alkaloid rich species predominate in the Families Annonaceae, Apocynaceae and Rubiaceae and to a lesser extent in Lauraceae, Menispermaceae, Verbanaceae, Euphorbiaceae and Rutaceae. 

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